Metoclopramide

What it is

Metoclopramide is a manufactured small molecule, a substituted benzamide, available as tablets, an oral solution, an orally disintegrating tablet, a nasal spray and an injection. European regulators describe it as having parasympathomimetic activity as well as being a dopamine D2 receptor antagonist acting on the brain's chemoreceptor trigger zone, with serotonin 5-HT3 antagonist properties too. It has been on the market in Europe since the 1960s. It crosses the blood-brain barrier, which is why its characteristic harms are neurological.

What the research says

It moves the stomach along and settles nausea, and the evidence is stronger for the nausea than for the stomach. In a network meta-analysis of 29 gastroparesis trials, oral metoclopramide ranked first for nausea, fullness and bloating, but the reviewers say plainly that this rested on only one small trial, and no drug except clebopride and domperidone beat placebo on global symptoms. For acute migraine given by injection, a meta-analysis of 13 trials found metoclopramide about three times as likely as placebo to give significant pain reduction, though a later review judged those placebo-controlled trials too weak to pool. For increasing breast-milk production it failed: it raised prolactin but did not raise milk volume. The harms are the reason it carries a boxed warning: tardive dyskinesia, a movement disorder that is often permanent, with risk rising the longer it is taken.

Evidence grade: Disputed.

How it works

Drug class: Substituted benzamide: dopamine D2 receptor antagonist with prokinetic and antiemetic actions, also a serotonin 5-HT3 receptor antagonist

Metoclopramide speeds up the top end of the gut and blocks the vomiting signal. It blocks dopamine D2 receptors, which is where both the benefit and the harm come from: in the gut wall that blockade, together with an effect that makes tissue more responsive to acetylcholine, raises the force of stomach contractions, relaxes the outlet of the stomach and pushes the duodenum and jejunum along, so the stomach empties faster and the lower oesophageal sphincter tightens. In the brain the same dopamine blockade acts on the chemoreceptor trigger zone to stop nausea, and because the drug crosses into the brain it can also produce movement disorders. The label is explicit that the exact mechanism in reflux and gastroparesis has not been fully established. (Source 1)

Boxed warning

Metoclopramide, including Reglan, can cause tardive dyskinesia (TD), a potentially irreversible serious movement disorder. In patients treated with metoclopramide, including Reglan, the risk of developing TD increases with duration of treatment and total cumulative dosage [see Warnings and Precautions (5.1)].

(Source 2)

What it is used for

• The US label approves this use but limits it to 12 weeks and states it has not been shown safe and effective beyond that. European regulators reviewing the same class of evidence in 2013 concluded there is little evidence of efficacy in reflux or dyspepsia and that the data are not consistent, and withdrew the indication. Evidence: disputed. (Source 3)
• A 2023 network meta-analysis of 29 randomised trials ranked oral metoclopramide first for nausea, fullness and bloating, with bloating reaching statistical significance, but states this rested on only one small trial and that confidence in the evidence was low to moderate for most comparisons. European regulators concluded the data cannot be considered supportive, because gastroparesis needs long-term treatment and no consistent long-term benefit was shown. Evidence: limited. (Source 4)
• Off-label in the US, where the tablet label lists only reflux and diabetic gastroparesis; a licensed indication for the injection in parts of Europe. A BMJ meta-analysis of 13 randomised trials in 655 adults found metoclopramide more likely than placebo to give significant pain reduction, odds ratio 2.84 (95% CI 1.05 to 7.68). A later systematic review judged the placebo-controlled trials too methodologically weak to pool, while agreeing the direction favours metoclopramide. Evidence: limited. (Source 5)
• A meta-analysis of eight trials in 342 lactating women found metoclopramide raised serum prolactin significantly but did not increase milk volume, and its authors recommend against using it for this purpose. The US label says the published data are not adequate to support an effect on milk production and warns to monitor breastfed newborns for movement reactions and methaemoglobinaemia. Evidence: not-supported. (Source 6)
• Not an indication on the US tablet label read here. European regulators concluded there is sufficient evidence of efficacy for post-operative nausea and vomiting and, taken together, data indicative of an effect on nausea and vomiting of different causes, while restricting doses and duration. No systematic review of these uses was reached in this run. Evidence: limited. (Source 7)
• The US label states metoclopramide tablets are not recommended in children because of tardive dyskinesia, other extrapyramidal symptoms and methaemoglobinaemia in newborns. European regulators found very limited information supporting efficacy in children and that the risk of acute dystonia is higher in children than adults. Evidence: not-supported. (Source 3)

Interactions

• Alcohol (label): The label groups alcohol with sedatives, hypnotics, opiates and anxiolytics as central nervous system depressants, and says the combination increases the risk of central nervous system depression. It separately warns that metoclopramide can impair the mental and physical ability needed for driving, and that CNS depressants such as alcohol may increase that effect. (Source 8)
• Alcohol and other sedating substances, driving (label): The label states metoclopramide may impair the mental or physical abilities needed for hazardous tasks such as driving, and that taking central nervous system depressants, alcohol among them, may increase that effect. (Source 9)
• Antipsychotic medicines (label): Both block dopamine, so the effects add up. The label says concomitant use risks more frequent and more severe tardive dyskinesia, other movement reactions and neuroleptic malignant syndrome, and should be avoided. (Source 8)
• Strong CYP2D6 inhibitors, including fluoxetine, paroxetine, bupropion and quinidine (label): These slow the breakdown of metoclopramide, pushing its blood levels up and with them the risk of movement reactions. The label's response is to reduce the metoclopramide dose. (Source 8)
• Monoamine oxidase inhibitors (label): Metoclopramide can release catecholamines and raise blood pressure; with a monoamine oxidase inhibitor that risk increases, and the label says to avoid the combination. (Source 8)
• Dopamine-boosting medicines such as levodopa, pramipexole, ropinirole, bromocriptine and cabergoline (label): These work in the opposite direction to metoclopramide at the dopamine receptor, so each blunts the other: metoclopramide works less well, and parkinsonian symptoms may worsen. The label says to avoid using them together. (Source 10)
• Supplements and herbs that act on serotonin, such as St John's wort, 5-HTP and tryptophan (theoretical): No study of metoclopramide with any serotonergic supplement was found in this run. The basis for caution is that the label lists serotonin syndrome as an adverse reaction when metoclopramide is combined with serotonergic agents, and these supplements act on serotonin. This is reasoning by extension from a drug-class statement, not evidence about the supplements themselves. (Source 11)
• Food, and the timing of meals (label): Timing is part of the drug's action rather than a hazard: the label has each dose taken thirty minutes before a meal and at bedtime, because the point is to get the stomach moving before food arrives. Separately, drugs that slow the gut, including anticholinergics, antidiarrhoeals and opiates, reduce how much metoclopramide is absorbed. (Source 12)
• Insulin, and other medicines whose absorption depends on gut speed (label): By speeding the stomach up, metoclopramide changes when food and other drugs reach the intestine. The label says this may raise blood glucose, so insulin doses may need adjusting, and that absorption of digoxin and some antimicrobials falls while that of sirolimus, tacrolimus and cyclosporine rises. (Source 13)

Stopping it

• Stopping is built into how the drug is meant to be used: the label limits reflux treatment to 12 weeks and says to avoid more than 12 weeks in diabetic gastroparesis, monitoring for movement reactions if longer use is unavoidable. (Source 12)
• If tardive dyskinesia appears, stopping can help: the label states it may remit partly or completely if treatment is discontinued, though the warning also says it is potentially irreversible. (Source 14)
• There is a withdrawal pattern of its own. The label records that nervous-system reactions have occurred after metoclopramide was stopped, including dizziness, nervousness and headaches. (Source 11)
• Parkinsonian symptoms caused by the drug generally settle within two to three months of stopping it, and for motor restlessness the label contemplates restarting at a lower dose if symptoms resolve. (Source 15)

What goes wrong

Metoclopramide can cause tardive dyskinesia, a disfiguring and often permanent movement disorder, with risk rising the longer it is taken and the more is taken in total. (Source 14)

• Official position, Certainty not rated.
• Size: Not stated; the basis of the boxed warning.
• Who: Patients treated with metoclopramide; risk raised in the elderly, especially elderly women, and in people with diabetes.
• How long: Risk increases with duration; treatment beyond 12 weeks is to be avoided.
• Result: No rate is given in the warning itself; the drug is contraindicated in anyone with a history of tardive dyskinesia.
• Funding: industry-funded (manufacturer's prescribing information)

Limit of this finding: A label section states a hazard and what to do about it; it is a regulatory position, not a measurement. No rate, no comparison with placebo and no absolute risk is given here. The boxed warning gives no numerical risk at all, only that risk rises with duration and total cumulative dose; the only published estimate in this entry is the under-1% figure from a narrative review, which is contested.

Metoclopramide, including Reglan, can cause tardive dyskinesia (TD), a syndrome of potentially irreversible and disfiguring involuntary movements of the face or tongue, and sometimes of the trunk and/or extremities. Metoclopramide, including Reglan, may also suppress, or partially suppress, the signs of TD, and may delay the diagnosis of TD because it may mask the underlying disease process. The effect of this symptomatic suppression upon the long-term course of TD is unknown. TD may remit, partially or completely, if Reglan treatment is discontinued. In patients treated with metoclopramide, including Reglan, the risk of developing TD and the likelihood that TD will become irreversible increases with duration of treatment and total cumulative dosage. Additionally, the risk of developing TD is increased in elderly patients, especially in elderly women [see Use in Specific Populations (8.5)], and in patients with diabetes mellitus

A review of the published evidence put the risk of metoclopramide-induced tardive dyskinesia at probably under 1%, far below the 1 to 10% that guidelines had suggested. (Source 16)

• Expert review, not systematic, Low certainty.
• Size: Not stated; narrative PubMed search with no pooling method.
• Who: Patients treated with metoclopramide for gastrointestinal symptoms.
• How long: Long-term or high-dose use.
• Result: Risk likely under 1%, against an estimated 1 to 10% previously suggested in national guidelines.
• Funding: not stated.

Limit of this finding: This is a narrative review with no stated pooling method, so the under-1% figure is the authors' reading of published reports rather than a pooled estimate, and they say themselves that community prevalence still needs study. One sentence in the review is garbled in the journal itself, 'potential mechanisms that may alter and to summarize', and the quotation keeps it. The less-than sign in '<1%' is the source's own character.

Available data show that risk of tardive dyskinesia from metoclopramide use is likely to be <1%, much less than the estimated 1-10% risk previously suggested in national guidelines

Akathisia, a distressing restlessness, was four times more common when 10 mg of metoclopramide was pushed in over two minutes than when infused over fifteen. (Source 17)

• Randomized trial, Moderate certainty.
• Size: 300 patients (154 slow infusion, 146 bolus)
• Who: Emergency department patients with nausea and vomiting, headache, or both.
• How long: Single 10 mg intravenous dose.
• Result: Akathisia 9/154 (5.8%) with slow infusion versus 36/146 (24.7%) with bolus, p < 0.001, OR 5.273, 95% CI 2.43 to 11.403. The paper also reports severe akathisia in 13/45 (28.8%) overall and prints 30.5% (11/36) in the bolus group versus 22.2% (2/9) in the slow-infusion group with p = 0.009, but that p value does not follow from those counts.
• Funding: not stated.

Limit of this finding: The overall akathisia comparison in this trial is sound: 9 of 154 against 36 of 146, a difference that is both large and consistent with the reported p value. The severe-akathisia comparison is not: 11 of 36 against 2 of 9 cannot give p = 0.009, because a two-sided exact test on those counts gives roughly p = 0.7, and the paper also rounds 13 of 45 to 28.8% where it is 28.9%. The quotation is left as published. Do not read the severe-akathisia difference between the two infusion rates as established. The source also prints 'A total of 300 patients presented to the ED met the inclusion criteria' and 'Severe akathisia were observed', its own wording, which the quotation keeps.

Nine of the 154 patients in the SIG group (5.8%) had akathisia compared with 36/146 patients (24.7%) in the BIG group (p < 0.001, OR 5.273, 95% CI 2.43 to 11.403). Severe akathisia were observed in 13/45 (28.8%). The incidence of severe akathisia was significantly higher in the BIG group (30.5%; 11/36) than in the SIG group (22.2%; 2/9), p = 0.009

Restlessness, drowsiness, fatigue and lassitude occurred in about one in ten people taking 10 mg four times daily, and depression with suicidal ideation less often. (Source 11)

• Official position, Certainty not rated.
• Size: Not stated; clinical studies and post-marketing reports summarised in the label.
• Who: Patients receiving 10 mg of metoclopramide four times daily.
• How long: Incidence correlated with dose and duration.
• Result: About 10% for restlessness, drowsiness, fatigue and lassitude; insomnia, headache, confusion, dizziness and depression with suicidal ideation less frequent; convulsive seizures, hallucinations, neuroleptic malignant syndrome and serotonin syndrome also listed.
• Funding: industry-funded (manufacturer's prescribing information)

Limit of this finding: A label section states a hazard and what to do about it; it is a regulatory position, not a measurement. No rate, no comparison with placebo and no absolute risk is given here.

The most common adverse reactions (in approximately 10% of patients receiving 10 mg of metoclopramide four times daily) were restlessness, drowsiness, fatigue, and lassitude. In general, the incidence of adverse reactions correlated with the dosage and duration of metoclopramide administration

Acute dystonic reactions occurred at 30 to 40 mg daily, more often in adults under 30 and more often in children, usually within the first 24 to 48 hours. (Source 18)

• Official position, Certainty not rated.
• Size: Not stated; label summary.
• Who: Patients treated with metoclopramide, especially adults under 30 and children.
• How long: First 24 to 48 hours after starting.
• Result: No rate is given; reactions included involuntary limb movements, facial grimacing, torticollis, oculogyric crisis and, rarely, stridor and breathlessness from laryngospasm.
• Funding: industry-funded (manufacturer's prescribing information)

Limit of this finding: A label section states a hazard and what to do about it; it is a regulatory position, not a measurement. No rate, no comparison with placebo and no absolute risk is given here.

Extrapyramidal symptoms (EPS), such as acute dystonic reactions, occurred in patients treated with metoclopramide dosages of 30 mg to 40 mg daily. Such reactions occurred more frequently in adults less than 30 years of age and at higher than recommended dosages. EPS occurred more frequently in pediatric patients compared to adults (Reglan is not approved for use in pediatric patients). Symptoms can occur in the first 24 to 48 hours after starting metoclopramide. Symptoms included involuntary movements of limbs and facial grimacing, torticollis, oculogyric crisis, rhythmic protrusion of tongue, bulbar type of speech, trismus, or dystonic reactions resembling tetanus

European regulators concluded that acute dystonia risk is dose-related and higher in children, and that the elderly are at particular risk of tardive dyskinesia after long-term treatment. (Source 19)

• Official position, Certainty not rated.
• Size: Not stated; Article 31 referral review of safety data.
• Who: All ages; children and the elderly singled out.
• How long: Long-term treatment for the tardive dyskinesia risk.
• Result: No rate given; giving intravenous doses as a slow bolus over at least three minutes was found to lower the risk of all dystonic reactions.
• Funding: independent (European regulatory review)

Limit of this finding: This is a regulatory summary of safety data with no rates, no denominators and no comparison group. The three-minute slow-bolus finding is the Committee's reading of the submitted data, and the one randomised trial in this entry that tested infusion rate supports the direction for akathisia overall.

From the data assessed, it appears that the risk of acute dystonias is increased when using high doses, and is higher in children than in adults. The elderly appear to be at particular risk of developing tardive dyskinesia following long-term treatment, which in some cases may be irreversible. The slow administration of intravenous doses as a slow bolus over at least 3 minutes lowers the risk of all dystonic reactions

Overdose has caused drowsiness, disorientation, movement reactions, methaemoglobinaemia and sometimes death, and there is no specific antidote. (Source 20)

• Official position, Certainty not rated.
• Size: Not stated; label summary of reported overdoses.
• Who: People who have taken too much metoclopramide.
• How long: Not stated.
• Result: Neuroleptic malignant syndrome reported with overdose; methaemoglobinaemia reversible with intravenous methylene blue, which may itself cause fatal haemolytic anaemia in G6PD deficiency; dialysis does not remove significant amounts.
• Funding: industry-funded (manufacturer's prescribing information)

Limit of this finding: A label section states a hazard and what to do about it; it is a regulatory position, not a measurement. No rate, no comparison with placebo and no absolute risk is given here.

Manifestations of metoclopramide overdosage included drowsiness, disorientation, extrapyramidal reactions, other adverse reactions associated with metoclopramide use (including, e.g., methemoglobinemia), and sometimes death. Neuroleptic malignant syndrome (NMS) has been reported in association with metoclopramide overdose and concomitant treatment with another drug associated with NMS [see Warnings and Precautions (5.1, 5.2, 5.3)]. There are no specific antidotes for Reglan overdosage. If over-exposure occurs, call your Poison Control Center at 1-800-222-1222 for current information on the management of poisoning or overdosage

Metoclopramide raises prolactin, which can suppress reproductive hormones and cause milk leakage, absent periods, breast enlargement in men and impotence. (Source 21)

• Official position, Certainty not rated.
• Size: Not stated; label summary.
• Who: Patients of both sexes treated with metoclopramide.
• How long: Not stated.
• Result: No rate is given; these are reported reactions grouped by body system, with no denominator and no placebo comparison.
• Funding: industry-funded (manufacturer's prescribing information)

Limit of this finding: A label section states a hazard and what to do about it; it is a regulatory position, not a measurement. No rate, no comparison with placebo and no absolute risk is given here. This is an undifferentiated list of reported reactions drawn partly from spontaneous reports, which the same section says cannot be used to estimate frequency or to establish that the drug caused them.

Galactorrhea, amenorrhea, gynecomastia, impotence secondary to hyperprolactinemia Cardiovascular Disorders: Acute congestive heart failure, possible atrioventricular block, hypotension, hypertension, supraventricular tachycardia, bradycardia, fluid retention Gastrointestinal Disorders: Nausea, bowel disturbances (primarily diarrhea)

Metoclopramide passes into breast milk and breastfed infants have had gut reactions, with the label advising monitoring for movement reactions and methaemoglobinaemia. (Source 22)

• Official position, Certainty not rated.
• Size: Published clinical studies summarised in the label.
• Who: Breastfed infants of mothers taking metoclopramide.
• How long: Early puerperium to 12 weeks postpartum.
• Result: Estimated infant intake under 10% of the maternal weight-adjusted dose; 6 to 24 micrograms per kilogram per day at 3 to 9 days postpartum and 1 to 13 micrograms per kilogram per day at 8 to 12 weeks.
• Funding: industry-funded (manufacturer's prescribing information)

Limit of this finding: A label section states a hazard and what to do about it; it is a regulatory position, not a measurement. No rate, no comparison with placebo and no absolute risk is given here.

Breastfed infants exposed to metoclopramide have experienced gastrointestinal adverse reactions, including intestinal discomfort and increased intestinal gas formation (see Clinical Considerations). Metoclopramide elevates prolactin levels [see Warnings and Precautions (5.7)]; however, the published data are not adequate to support drug effects on milk production

Section 5.1 of the label does not only describe the tardive dyskinesia risk, it sets out what must be done about it: the drug is contraindicated in anyone with a history of the disorder, avoided alongside antipsychotics, reduced in the elderly, stopped immediately if signs appear, and capped at 12 weeks. (Source 14)

• Official position, Certainty not rated.
• Size: Not stated; the prevention and monitoring instructions attached to the boxed warning.
• Who: Anyone prescribed metoclopramide, with the elderly and people taking antipsychotics singled out.
• How long: Maximum 12 weeks for documented gastro-oesophageal reflux, and a total duration beyond 12 weeks to be avoided in diabetic gastroparesis.
• Result: No rate; the label states a contraindication, a dose reduction in the elderly, avoidance with antipsychotics, immediate discontinuation on signs of the disorder, and routine monitoring if longer use is unavoidable.
• Funding: industry-funded (manufacturer's prescribing information)

Limit of this finding: A label section states a hazard and what to do about it; it is a regulatory position, not a measurement. No rate, no comparison with placebo and no absolute risk is given here. These are instructions to a prescriber, not advice for a reader to act on, and the label attaches no risk figure to any of them.

Prevention, Mitigation, and Monitoring for TD • Reglan is contraindicated in patients with a history of TD. • Avoid use of Reglan in patients receiving concomitant antipsychotics due to the potential additive effects of TD [see Drug Interactions (7.1)]. • Reduce the Reglan dosage in the elderly [see Dosage and Administration (2.1, 2.2)]. • Use Reglan for the shortest duration of treatment and periodically reassess the need for continued treatment. • Immediately discontinue Reglan in patients who develop signs and symptoms of TD. • In patients with symptomatic, documented gastroesophageal reflux, the maximum duration of treatment is 12 weeks [see Dosage and Administration (2.2)]. • In patients with diabetic gastroparesis, avoid a total duration of treatment with metoclopramide products, including Reglan tablets, for longer than 12 weeks. If longer-term use is unavoidable, routinely monitor for signs and symptoms of TD. • If patients have continued TD symptoms, consider TD treatment.

For gastroparesis the label reduces the dose to 5 mg four times daily for older people and for mild hepatic impairment, and to 5 mg four times daily with a 20 mg daily maximum in moderate or severe hepatic impairment. (Source 23)

• Official position, Certainty not rated.
• Size: Not stated; regulatory dosing position.
• Who: Adults with diabetic gastroparesis who are elderly or have hepatic impairment.
• How long: Not stated.
• Result: 5 mg four times daily for mild hepatic impairment and elderly patients; 5 mg four times daily to a maximum of 20 mg a day for Child-Pugh B or C; 5 mg twice daily to a maximum of 10 mg a day in end-stage renal disease.
• Funding: industry-funded (manufacturer's prescribing information)

Limit of this finding: This is the label's own dosing table, flattened to one cell per line, so each population is followed by the dosage and the maximum printed against it. The superscript 1 on "5 mg1" is the label's footnote marker and its definition is the last paragraph of the block. In the printed table one dosage cell is shared by mild hepatic impairment and elderly patients. A table of dose reductions is a regulatory instruction to a prescriber, not a measurement, and no rate or risk estimate is attached to it.

Mild hepatic impairment (Child-Pugh A) Elderly patients [see Use in Specific Populations (8.5)] 5 mg1 four times daily (30 minutes before each meal and at bedtime) Moderate or severe hepatic impairment (Child-Pugh B or C) [see Use in Specific Populations (8.7)] 5 mg four times daily (30 minutes before each meal and at bedtime) 20 mg

What the evidence supports

In a network meta-analysis of gastroparesis drug trials, oral metoclopramide ranked first for nausea, fullness and bloating, with the bloating estimate statistically significant. (Source 4)

• Systematic review, Low certainty.
• Size: 3,772 patients across 29 randomised controlled trials; the metoclopramide ranking rested on one small trial.
• Who: Adults with gastroparesis, diabetic and idiopathic.
• How long: Varied; the review notes trials shorter than 4 weeks to 9 weeks or more.
• Result: Nausea RR of not improving 0.46 (95% CI 0.21 to 1.00), P-score 0.95; fullness RR 0.67 (95% CI 0.35 to 1.28), P-score 0.86; bloating RR 0.53 (95% CI 0.30 to 0.93), P-score 0.97.
• Funding: not stated.

Limit of this finding: Two things have to be carried with these numbers. The relative risks are risks of NOT improving, a definition that sits in the paper's methods rather than in this passage, so a value below 1 favours the drug and a reader who assumes the opposite will read every figure backwards. And the P-score is a ranking probability across the network, not an observed event rate: 'ranked first' is an ordering. For metoclopramide the ordering rests on one small trial, as the passage says, the nausea interval stops exactly at 1.00 and the fullness interval, 0.35 to 1.28, crosses 1, so only the bloating result is statistically significant.

For individual symptoms, oral metoclopramide ranked first for nausea (RR 0.46; 95% CI, 0.21-1.00; P-score = .95), fullness (RR 0.67; 95% CI, 0.35-1.28; P-score = .86), and bloating (RR 0.53; 95% CI, 0.30-0.93; P-score = .97), based on only 1 small trial

A meta-analysis of randomised trials found parenteral metoclopramide about three times as likely as placebo to give a significant reduction in acute migraine pain. (Source 5)

• Meta-analysis, Low certainty.
• Size: 655 adults across 13 eligible trials, from 596 abstracts reviewed.
• Who: Adults with acute migraine, largely in emergency departments.
• How long: Single acute treatment episodes.
• Result: Odds ratio 2.84, 95% CI 1.05 to 7.68, for significant reduction in migraine pain versus placebo.
• Funding: not stated.

Limit of this finding: The pooled odds ratio's confidence interval, 1.05 to 7.68, only just excludes 1 and is very wide, so the result is reported as significant but the size of any benefit is highly uncertain. An odds ratio is not an absolute benefit, and the meta-analysis gives no absolute risk reduction or number needed to treat. The paper also reports that heterogeneity prevented pooling for combination treatment, so the combination claims are not pooled results.

In studies comparing metoclopramide with placebo, metoclopramide was more likely to provide significant reduction in migraine pain (odds ratio 2.84, 95% confidence interval 1.05 to 7.68)

The authors of that meta-analysis conclude metoclopramide is an effective treatment for migraine headache and should be considered a primary agent in emergency departments. (Source 5)

• Meta-analysis, Low certainty.
• Size: 655 adults across 13 trials.
• Who: Adults with acute migraine.
• How long: Single acute treatment episodes.
• Result: Narrative conclusion; treatments including metoclopramide were as or more effective than comparators for pain, nausea and relapse in all studies reporting those outcomes.
• Funding: not stated.

Limit of this finding: The pooled odds ratio's confidence interval, 1.05 to 7.68, only just excludes 1 and is very wide, so the result is reported as significant but the size of any benefit is highly uncertain. An odds ratio is not an absolute benefit, and the meta-analysis gives no absolute risk reduction or number needed to treat. The paper also reports that heterogeneity prevented pooling for combination treatment, so the combination claims are not pooled results. The recommendation to treat metoclopramide as a primary agent is these authors' own conclusion from 2004, not the position of a guideline body.

Metoclopramide is an effective treatment for migraine headache and may be effective when combined with other treatments. Given its non-narcotic and antiemetic properties, metoclopramide should be considered a primary agent in the treatment of acute migraines in emergency departments

Even a review critical of the migraine evidence agrees the placebo-controlled trials point the same way and that use in the emergency department is reasonable. (Source 24)

• Systematic review, Very low certainty.
• Size: Number of included studies not stated in the record read.
• Who: Patients with migraine attack in emergency departments.
• How long: Single acute treatment episodes.
• Result: Reported as favouring metoclopramide over placebo for ceasing headache and for lower rescue-drug need, with no pooled estimate because the trials could not be pooled.
• Funding: not stated.

Limit of this finding: Despite its own title and the way it is indexed, this review performed no meta-analysis: it states that the trials 'lack high methodological quality even to perform a meta-analysis', so there is no pooled estimate, no risk ratio and no confidence interval anywhere in it. It must not be cited as quantitative evidence for metoclopramide. It is a single-author review, and its sentence keeps the double conjunction 'Although ... however' that the journal prints.

Although the studies comparing parenteral metoclopramide to placebo in ceasing migraine headache favor metoclopramide to placebo and lower rates of rescue drug need, however, they lack high methodological quality even to perform a meta-analysis. Meanwhile, the effect of metoclopramide in ceasing migraine headache is also comparable to active comparators. It seems reasonable to use metoclopramide in migraine attacks in EDs according to the current literature

In an emergency-department trial, metoclopramide relieved the presenting symptom in about nine in ten patients regardless of how fast it was infused. (Source 17)

• Randomized trial, Moderate certainty.
• Size: 300 patients (154 slow infusion, 146 bolus)
• Who: Emergency department patients with nausea and vomiting, headache, or both, at a tertiary university hospital.
• How long: Single dose of 10 mg intravenously.
• Result: Symptom relief in 137/146 (90.8%) with bolus and 139/154 (90.2%) with slow infusion.
• Funding: not stated.

Limit of this finding: This measured relief of the presenting symptom after a single 10 mg intravenous dose in an emergency department, with no placebo arm: both groups got metoclopramide, so the roughly 90% relief cannot be separated from what would have happened anyway. The overall akathisia comparison in this trial is sound: 9 of 154 against 36 of 146, a difference that is both large and consistent with the reported p value. The severe-akathisia comparison is not: 11 of 36 against 2 of 9 cannot give p = 0.009, because a two-sided exact test on those counts gives roughly p = 0.7, and the paper also rounds 13 of 45 to 28.8% where it is 28.9%. The quotation is left as published. Do not read the severe-akathisia difference between the two infusion rates as established. The source also prints 'A total of 300 patients presented to the ED met the inclusion criteria' and 'Severe akathisia were observed', its own wording, which the quotation keeps.

Metoclopramide successfully relieved the presenting symptom(s) of 137/146 (90.8%) and 139/154 (90.2%) patients in the BIG and SIG groups, respectively

What the evidence does not support

That top ranking in gastroparesis sits inside a review whose overall finding was that no drug other than clebopride and domperidone beat placebo on global symptoms. (Source 4)

• Systematic review, Low certainty.
• Size: 3,772 patients across 29 randomised controlled trials.
• Who: Adults with gastroparesis.
• How long: Varied.
• Result: Clebopride RR 0.30 (95% CI 0.16 to 0.57), domperidone RR 0.68 (95% CI 0.48 to 0.98); no other drug superior to placebo on global symptoms.
• Funding: not stated.

Limit of this finding: The relative risks here are risks of not improving, so values below 1 favour the drug; that definition is in the paper's methods, not in this passage. The P-scores are ranking probabilities, not event rates.

Based on global symptoms, clebopride ranked first for efficacy (RR, 0.30; 95% CI, 0.16-0.57; P-score = .99) followed by domperidone (RR, 0.68; 95% CI, 0.48-0.98; P-score = .76). No other drug was superior to placebo

The reviewers state that confidence in the gastroparesis evidence was low to moderate for most comparisons and that there is an unmet need for effective treatment. (Source 25)

• Systematic review, Low certainty.
• Size: 3,772 patients across 29 randomised controlled trials.
• Who: Adults with gastroparesis.
• How long: Varied.
• Result: Certainty judgement rather than an effect estimate.
• Funding: not stated.

Limit of this finding: This is the reviewers' certainty judgement, not an effect estimate. Low to moderate confidence means the true effects could differ substantially from the ones ranked.

but confidence in the evidence was low to moderate for most comparisons. There is an unmet need for efficacious therapies for gastroparesis

Placebo alone produces a response in nearly a third of gastroparesis trial participants, so improvement on metoclopramide outside a trial cannot be attributed to the drug. (Source 26)

• Meta-analysis, Moderate certainty.
• Size: 35 eligible studies; 23 reporting a composite endpoint.
• Who: Patients in randomised drug trials for gastroparesis.
• How long: Trials from under 4 weeks to 9 weeks or more.
• Result: Pooled placebo response 29.3% (95% CI 23.7% to 35.2%); higher in idiopathic than diabetic gastroparesis, 34.2% versus 28.1%, and higher in shorter trials, 32.6% under 4 weeks versus 23.2% at 9 weeks or more.
• Funding: not stated.

Limit of this finding: The pooled placebo response was calculated with every dropout counted as a treatment failure, an assumption stated in the paper's methods, so it is a conservative figure. The authors' own conclusion is that trials need to run at least eight weeks, use validated questionnaires and separate the gastroparesis subtypes before therapeutic gain can be judged. The figures are placebo rates, not metoclopramide rates.

Among 23 trials reporting a composite endpoint of improvement, the pooled placebo response rate was 29.3% (95% CI, 23.7%-35.2%). Pooled placebo response rates were higher in idiopathic compared with diabetic gastroparesis (34.2% vs 28.1%), among trials that did not use validated symptom questionnaires (31.2% vs 27.4%), and in RCTs of shorter duration (<4 weeks, 32.6% vs ≥9 weeks, 23.2%)

A later systematic review judged the placebo-controlled migraine trials of intravenous metoclopramide too methodologically weak even to pool. (Source 24)

• Systematic review, Very low certainty.
• Size: Number of included studies not stated in the record read.
• Who: Patients with migraine attack in emergency departments.
• How long: Single acute treatment episodes.
• Result: No pooled estimate was produced; the review also reports metoclopramide's effect comparable to active comparators.
• Funding: not stated.

Limit of this finding: Despite its own title and the way it is indexed, this review performed no meta-analysis: it states that the trials 'lack high methodological quality even to perform a meta-analysis', so there is no pooled estimate, no risk ratio and no confidence interval anywhere in it. It must not be cited as quantitative evidence for metoclopramide. It is a single-author review, and its sentence keeps the double conjunction 'Although ... however' that the journal prints.

An earlier meta-analysis favors metoclopramide over placebo but includes studies with significant methodological errors and heterogeneity. The present article aimed to review the literature to reveal studies comparing metoclopramide to either placebo or active comparators. A literature search including PubMed, Cochrane Database, and Google Scholar was performed by using the evidence-based process for determining the study quality. Although the studies comparing parenteral metoclopramide to placebo in ceasing migraine headache favor metoclopramide to placebo and lower rates of rescue drug need, however, they lack high methodological quality even to perform a meta-analysis. Meanwhile, the effect of metoclopramide in ceasing migraine headache is also comparable to active comparators. It seems reasonable to use metoclopramide in migraine attacks in EDs according to the current literature. However, further studies with high methodological quality are needed

Metoclopramide raised prolactin but did not increase milk volume in lactating women, and the reviewers recommend against using it for that purpose. (Source 6)

• Systematic review, Low certainty.
• Size: 342 lactating women across eight trials.
• Who: Breastfeeding women with term or preterm infants.
• How long: Not stated.
• Result: No increase in milk volume versus control; significant increase in serum prolactin; no significant adverse events reported.
• Funding: not stated.

Limit of this finding: The meta-analysis is small: eight trials and 342 women in total, and the review reports no pooled effect size in this passage. The dissociation is the useful part: prolactin rose, milk volume did not, so a measurable hormonal effect did not translate into the outcome mothers care about. 'No significant adverse events were reported' in trials this small does not mean the drug is free of the harms described elsewhere in this entry.

The meta-analysis of these trials revealed that metoclopramide did not increase the milk volume of the intervention groups compared to that of the control groups. There was a significant increase in the serum concentrations of prolactin when the mothers were administered metoclopramide. No significant adverse events were reported. CONCLUSION: Metoclopramide did not improve milk production in lactating women. Therefore, we do not recommend using metoclopramide to increase milk production in lactating women

European regulators concluded the gastroparesis data cannot be considered supportive, because benefit in short-term use did not persist long term, and found little evidence of efficacy in reflux or dyspepsia. (Source 27)

• Official position, Certainty not rated.
• Size: Not stated; Article 31 referral review of the submitted literature.
• Who: Patients with gastrointestinal motility disorders, gastro-oesophageal reflux disease and dyspepsia.
• How long: The Committee's point was that these are chronic conditions needing long-term treatment.
• Result: No pooled estimate; the Committee concluded the benefit-risk balance in these indications is negative.
• Funding: independent (European regulatory review)

Limit of this finding: This is a regulatory conclusion on the evidence submitted to a 2013 Article 31 referral, not a pooled analysis, and the Committee gives no effect estimate. It is the European position and it differs from the US label, which still approves both uses; that disagreement is recorded separately in this entry.

While metoclopramide was found to improve gastric emptying and relieve symptoms in diabetic and idiopathic gastroparesis in short term treatment when compared to placebo, no consistent benefit was observed in the long term. Gastroparesis is often a chronic disorder, for which long term treatment is necessary, therefore existing data cannot be considered supportive of the use in this indication. Gastroesophageal reflux disease and dyspepsia Based on the data presented, there is little evidence of efficacy of metoclopramide in treatment of gastroesophageal reflux disease or dyspepsia and existing data is not consistent in terms of effect. Furthermore, existing studies included a very small number of patients and focused on a small duration of treatment. It is also noted that there are other well-established agents available for this indication, including proton pump inhibitors and H2 receptor antagonists, for which a positive benefit-risk balance has been clearly demonstrated for acute and chronic use. Both gastroesophageal reflux disease and dyspepsia may be chronic diseases, and therefore existing data cannot be considered sufficient to support the use in these indications

Where the evidence is mixed

The same reviewers say the community prevalence and the mechanisms of metoclopramide-induced tardive dyskinesia still need study before the benefit-risk balance can be stated clearly. (Source 16)

• Expert review, not systematic, Low certainty.
• Size: Not stated.
• Who: Patients treated with metoclopramide.
• How long: Not stated.
• Result: No estimate; the authors describe tardive dyskinesia as possibly an idiosyncratic response.
• Funding: not stated.

Limit of this finding: This is a narrative review with no stated pooling method, so the under-1% figure is the authors' reading of published reports rather than a pooled estimate, and they say themselves that community prevalence still needs study. One sentence in the review is garbled in the journal itself, 'potential mechanisms that may alter and to summarize', and the quotation keeps it. The less-than sign in '<1%' is the source's own character.

Tardive dyskinesia may represent an idiosyncratic response to metoclopramide; pharmacogenetics affect pharmacokinetic and dopamine receptor pharmacodynamics in response to neuroleptic agents that cause similar neurological complications. CONCLUSION: Community prevalence and pharmacogenetic mechanisms involved in metoclopramide-induced tardive dyskinesia require further study to define the benefit-risk ratio more clearly

Adverse events are also common on placebo in gastroparesis trials, at about one in three, so not every symptom on metoclopramide is caused by it. (Source 26)

• Meta-analysis, Moderate certainty.
• Size: 27 trials reporting placebo adverse events.
• Who: Patients in randomised drug trials for gastroparesis.
• How long: Trials from under 4 weeks to 9 weeks or more.
• Result: Adverse events in 33.8% of placebo patients (95% CI 26.4% to 41.8%); less common in idiopathic than diabetic gastroparesis, 17.9% versus 43.4%.
• Funding: not stated.

Limit of this finding: The pooled placebo response was calculated with every dropout counted as a treatment failure, an assumption stated in the paper's methods, so it is a conservative figure. The authors' own conclusion is that trials need to run at least eight weeks, use validated questionnaires and separate the gastroparesis subtypes before therapeutic gain can be judged. The figures are placebo rates, not metoclopramide rates.

Adverse events occurred in 33.8% (95% CI, 26.4%-41.8%) of patients with placebo, in 27 trials, and were less common in idiopathic compared with diabetic gastroparesis (17.9% vs 43.4%)

For the reflux indication the label sets a different and higher dose range than for gastroparesis, 10 to 15 mg four times daily to a maximum of 60 mg a day, with treatment limited to 4 to 12 weeks judged by endoscopy. (Source 28)

• Official position, Certainty not rated.
• Size: Not stated; regulatory dosing position.
• Who: Adults with symptomatic, documented gastro-oesophageal reflux who fail conventional therapy.
• How long: 4 to 12 weeks, with a maximum recommended duration of 12 weeks.
• Result: Recommended dosage 10 to 15 mg orally four times daily, each dose thirty minutes before a meal and at bedtime; maximum recommended daily oral dosage 60 mg; maximum duration 12 weeks.
• Funding: industry-funded (manufacturer's prescribing information)

Limit of this finding: A label section states a hazard and what to do about it; it is a regulatory position, not a measurement. No rate, no comparison with placebo and no absolute risk is given here. This is the dose a prescriber may use, not a dose for a reader. The same label states that metoclopramide has not been shown to be safe and effective for reflux beyond 12 weeks, and European regulators withdrew this indication in 2013 for lack of evidence of efficacy, so the existence of a dose range is not evidence that it works.

The recommended dosage of Reglan tablets is 10 to 15 mg orally four times daily. The maximum recommended daily oral dosage is 60 mg. • Administer each dose thirty minutes before a meal and at bedtime. • The recommended treatment duration is 4 to 12 weeks, as determined by endoscopic response. Use Reglan for the shortest duration of treatment and periodically reassess the need for continued treatment. • The maximum recommended duration of treatment is 12 weeks [see Warnings and Precautions (5.1)].

For reflux the label also allows intermittent use, a single dose of up to 20 mg before a situation that provokes symptoms, with dose reductions directed by its Table 1. (Source 29)

• Official position, Certainty not rated.
• Size: Not stated; regulatory dosing position.
• Who: Adults with symptomatic, documented gastro-oesophageal reflux who fail conventional therapy.
• How long: Not stated for the intermittent option.
• Result: A single dose of up to 20 mg before the provoking situation, with the Table 1 reductions for older people, hepatic impairment, CYP2D6 poor metabolisers, renal impairment and end-stage renal disease.
• Funding: industry-funded (manufacturer's prescribing information)

Limit of this finding: This is the label's own dosing table, flattened to one cell per line, so each population is followed by the dosage and the maximum printed against it. The superscript 1 on "5 mg1" is the label's footnote marker and its definition is the last paragraph of the block. In the printed table one dosage cell is shared by mild hepatic impairment and elderly patients. A table of dose reductions is a regulatory instruction to a prescriber, not a measurement, and no rate or risk estimate is attached to it.

If symptoms only occur intermittently or at specific times of the day, administer Reglan as a single dose up to 20 mg prior to the provoking situation. Consider dosage reductions for the populations and situations in Table 1.

Where the research disagrees

Whether metoclopramide should be used at all for gastroparesis and reflux

• US prescribing information for REGLAN tablets (DailyMed SPL, effective 2026), Regulatory position, approving reflux for 4 to 12 weeks and diabetic gastroparesis, with a duration limit: Relief of symptoms in adults with acute and recurrent diabetic gastroparesis. Limitations of Use: • Reglan has not been shown to be safe and effective for the treatment of symptomatic, documented gastroesophageal reflux for longer than 12 weeks (Source 3)
• European Medicines Agency, Committee for Medicinal Products for Human Use, Article 31 referral, 2013, Regulatory review of the submitted efficacy literature, which revoked these indications in the European Union: Based on the data presented, there is little evidence of efficacy of metoclopramide in treatment of gastroesophageal reflux disease or dyspepsia and existing data is not consistent in terms of effect (Source 27)

How large the risk of tardive dyskinesia actually is

• Rao and Camilleri, review article, Alimentary Pharmacology and Therapeutics 2010, Narrative review of published data with no stated pooling method: risk of tardive dyskinesia from metoclopramide use is likely to be <1%, much less than the estimated 1-10% risk previously suggested in national guidelines (Source 16)
• US prescribing information for REGLAN tablets (DailyMed SPL, effective 2026), boxed warning, Regulatory position carried as a boxed warning; it states no numerical risk, only that risk rises with duration and cumulative dose: Metoclopramide, including Reglan, can cause tardive dyskinesia (TD), a potentially irreversible serious movement disorder. In patients treated with metoclopramide, including Reglan, the risk of developing TD increases with duration of treatment and total cumulative dosage (Source 2)

What the boxed warning says, which differs between metoclopramide products

• REGLAN tablets (DailyMed SPL, effective 2026), LOINC 34066-1, Current Physician Labeling Rule format, with per-indication duration limits and a contraindication in prior tardive dyskinesia: In patients with diabetic gastroparesis, avoid a total duration of treatment with metoclopramide products, including Reglan tablets, for longer than 12 weeks. If longer term use is unavoidable, routinely monitor for signs and symptoms of TD (Source 2)
• Metoclopramide injection (DailyMed SPL, effective 2026), LOINC 34066-1, Older labelling format carrying the same hazard in different words, with a blanket 12-week limit and no contraindication clause in the box: Treatment with metoclopramide for longer than 12 weeks should be avoided in all but rare cases where therapeutic benefit is thought to outweigh the risk of developing tardive dyskinesia (Source 30)

How much

• Reference intake: There is no dietary reference intake for metoclopramide: it is a prescription medicine and the dose is set by the prescriber. As a position, the current US tablet label (DailyMed SPL, effective 2026) records 10 mg four times daily for diabetic gastroparesis in adults, each dose thirty minutes before a meal and at bedtime. (Source 12)
• Upper limit: As a position, the label sets the maximum recommended daily dosage for diabetic gastroparesis at 40 mg and tells prescribers to avoid treatment longer than 12 weeks. It also directs them to a table of reduced dosages for moderate or severe hepatic impairment (Child-Pugh B or C), creatinine clearance under 60 mL per minute, CYP2D6 poor metabolisers and concomitant strong CYP2D6 inhibitors. The separate reflux indication on the same label carries its own and higher maximum, recorded as a finding in this entry. (Source 12)
• Studied: The emergency-department akathisia trial gave 10 mg of metoclopramide intravenously, either as a slow infusion over 15 minutes or as a bolus over 2 minutes. (Source 17)
• Studied: The migraine meta-analysis pooled trials of parenteral metoclopramide in adults, used alone and in combination with other agents. (Source 5)
• Studied: The gastroparesis network meta-analysis ranked oral metoclopramide on individual symptoms, and states that this ranking rested on only one small trial. (Source 4)

A common belief, and what the research shows

The belief: Metoclopramide helps mothers make more breast milk.

What the research shows: It raises the hormone, not the milk. Eight randomised trials in 342 women were pooled, and the result was: "metoclopramide did not increase the milk volume of the intervention groups compared to that of the control groups. There was a significant increase in the serum concentrations of prolactin when the mothers were administered metoclopramide". The reviewers' own recommendation is against using it for this purpose, and the US label says the published data are not adequate to support an effect on milk production.

Questions and answers

What is it?

Metoclopramide is a manufactured small molecule, a substituted benzamide, not a nutrient and not something the body makes. European regulators describe it as having parasympathomimetic activity as well as blocking the dopamine D2 receptor, acting directly on the brain's chemoreceptor trigger zone, with serotonin 5-HT3 blocking properties as well. It has been licensed in Europe since the 1960s and comes as tablets, oral solution, suppository, nasal spray and injection. (Source 7)

What does it do in the body?

Two things at once. In the gut it raises the force of stomach contractions, relaxes the stomach outlet, pushes the duodenum and jejunum along and tightens the lower oesophageal sphincter, so the stomach empties faster; it does this without increasing stomach, bile or pancreatic secretions. In the brain it blocks dopamine at the vomiting centre, which is what settles nausea. The label states the exact mechanism in reflux and gastroparesis has not been fully established. (Source 1)

Is it good or bad for you?

It is a short-course drug whose main harm grows with time. The boxed warning says it can cause tardive dyskinesia, a potentially irreversible serious movement disorder, with the risk rising with duration of treatment and total cumulative dose. That is why the label caps treatment at 12 weeks, contraindicates it in anyone who has had tardive dyskinesia, and says to stop it immediately if signs appear. Against that sits real benefit in acute settings: it relieved the presenting symptom in about nine in ten emergency patients and beat placebo for migraine pain. For long-term gastroparesis, European regulators judged the benefit-risk balance negative. (Source 2)

How do you get more of it?

There is nothing to get more of from food or behaviour: metoclopramide exists only as a prescribed medicine. As a position, the label records 10 mg four times daily for diabetic gastroparesis in adults, each dose thirty minutes before a meal and at bedtime, with lower doses in the elderly, in liver or kidney impairment, in CYP2D6 poor metabolisers and alongside strong CYP2D6 inhibitors. For people vomiting too much to swallow tablets the label contemplates starting with the injection for up to ten days. (Source 12)

If it is harmful, what reduces it?

Stopping the drug is the main lever, and for the movement disorder it can be enough: the label states tardive dyskinesia may remit partly or completely if treatment is discontinued, although the boxed warning also calls it potentially irreversible. Parkinsonian symptoms generally settle within two to three months of stopping. For acute dystonic reactions the label names diphenhydramine or benztropine as treatments. In overdose there is no specific antidote, and dialysis does not remove significant amounts of the drug. (Source 18)

Why might someone be low in it or missing it?

The question does not apply. Nobody is deficient in metoclopramide, because it is a manufactured chemical and not a substance the body makes, stores or needs. What does vary between people is how fast they clear it: the label records reduced clearance in kidney and liver impairment and in CYP2D6 poor metabolisers, and lowers the dose for each, because higher levels mean more risk of movement reactions. (Source 7)

Which whole foods contain it or feed it?

No whole food contains metoclopramide and none feeds it. Food matters only for timing: the label has each dose taken thirty minutes before a meal and at bedtime, because the aim is to have the stomach already moving when food arrives. Nothing in the sources read describes a food or drink that increases or blocks the drug itself, though medicines that slow the gut reduce how much of it is absorbed. (Source 12)

What happens if you do not have it?

Nothing happens from never having metoclopramide, because it is not needed for health. For someone with gastroparesis who is not treated, the honest answer from the trial literature is that a sizeable share improve anyway: across 23 randomised trials the pooled response rate on placebo alone was 29.3%, higher in idiopathic than diabetic gastroparesis and higher in shorter trials. The reviewers of the drug evidence add that there is an unmet need for effective treatments, which is to say untreated gastroparesis often stays symptomatic and the available drugs do not reliably fix it. (Source 26)

How can you test for it?

There is no validated test, either to predict who will be harmed or to tell whether the drug is working; response is judged on symptoms and tardive dyskinesia is diagnosed clinically. The closest the literature comes is pharmacogenetics: a review searched for the DRD3 Ser9Gly polymorphism, cytochrome P450 and p-glycoprotein, and concluded that genetic factors affect how people handle the drug and respond at the dopamine receptor, but that the mechanisms still require study. The label acts on only part of this, lowering the dose in CYP2D6 poor metabolisers. (Source 16)

We searched: Searched the current DailyMed labels for REGLAN tablets, generic metoclopramide tablets and metoclopramide injection section by section, including clinical pharmacology, and PubMed via eutils for metoclopramide tardive dyskinesia prediction and pharmacogenetic testing; nothing describing a validated test was found.

References

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