Metoclopramide
Brand name: Reglan
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Symptomatic gastroesophageal reflux (documented, unresponsive to conventional therapy) | Adults | Treatment (4–12 weeks) | FDA Approved |
| Acute and recurrent diabetic gastroparesis | Adults | Symptomatic relief (2–8 weeks) | FDA Approved |
Metoclopramide is one of the few FDA-approved drugs for diabetic gastroparesis and is listed on the WHO Model List of Essential Medicines. It functions as both a prokinetic agent (accelerating gastric emptying) and an antiemetic (via central dopamine D2 receptor blockade in the chemoreceptor trigger zone). The drug is not recommended for pediatric use due to the increased risk of extrapyramidal symptoms and methemoglobinemia in neonates. Treatment should not exceed 12 weeks due to the risk of potentially irreversible tardive dyskinesia.
Prevention of chemotherapy-induced nausea and vomiting (CINV) — Evidence quality: Moderate. Used at higher doses (1–2 mg/kg IV) before 5-HT3 antagonists became available; now largely replaced by ondansetron and NK1 antagonists but still used in some protocols.
Prevention of postoperative nausea and vomiting (PONV) — Evidence quality: High. 10–20 mg IV/IM near end of surgery; established efficacy but EPS risk limits use as first-line agent.
Migraine-associated nausea and vomiting — Evidence quality: Moderate. 10 mg IV in ED settings; improves gastric absorption of co-administered oral analgesics.
Nausea and vomiting of pregnancy — Evidence quality: Moderate. Used as second-line agent; large cohort studies show no evidence of teratogenicity.
Small bowel intubation facilitation — Evidence quality: Moderate. 10 mg IV to accelerate passage of nasogastric/intestinal tubes through the pylorus.
Radiologic GI procedures — Evidence quality: Moderate. Accelerates barium transit; prevents vomiting after oral barium ingestion.
Dosing
Adult Dosing by Clinical Scenario
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| GERD — continuous therapy | 10–15 mg PO QID | 10–15 mg QID for 4–12 weeks | 60 mg/day | 30 min before each meal and at bedtime Duration determined by endoscopic response; do not exceed 12 weeks |
| GERD — intermittent (situational) therapy | Up to 20 mg PO × 1 | Single dose before provoking situation | 20 mg per dose | Use when symptoms occur only at specific times Consider dosage reductions in special populations |
| Diabetic gastroparesis — acute/recurrent | 10 mg PO QID | 10 mg QID for 2–8 weeks | 40 mg/day | 30 min before each meal and at bedtime If unable to take oral, use IV/IM for up to 10 days then switch to PO |
| PONV prophylaxis (off-label) | 10–20 mg IV/IM × 1 | Single dose | 20 mg | Given near end of surgery IM preferred at end of procedure |
| Small bowel intubation facilitation (off-label) | 10 mg IV × 1 | Single dose | 10 mg | Given over 1–2 minutes |
Special Population Dosing Adjustments
| Population | GERD Dose | Gastroparesis Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Elderly (≥65 years) | 5 mg QID (start) | 5 mg QID (start) | Titrate to adult dose if tolerated | Increased sensitivity to TD and parkinsonian effects Elderly women at highest TD risk |
| Moderate–severe hepatic impairment (Child-Pugh B/C) | 5 mg QID or 10 mg TID | 5 mg QID | 30 mg/day (GERD); 20 mg/day (gastroparesis) | Reduced clearance |
| Renal impairment (CrCl ≤60 mL/min) | 5 mg QID or 10 mg BID | 5 mg BID | 20 mg/day (GERD); 10 mg/day (gastroparesis) | Clearance reduced ~50%; t½ prolonged |
| ESRD (HD or CAPD) | 5 mg QID or 10 mg BID | 5 mg BID | 20 mg/day (GERD); 10 mg/day (gastroparesis) | Dialysis removes relatively little drug |
| CYP2D6 poor metabolizers | 5 mg QID or 10 mg BID | 5 mg BID | 20 mg/day (GERD); 10 mg/day (gastroparesis) | Same reductions as renal impairment |
| Concomitant strong CYP2D6 inhibitors | 5 mg QID or 10 mg BID | 5 mg BID | 20 mg/day (GERD); 10 mg/day (gastroparesis) | Inhibitors: quinidine, bupropion, fluoxetine, paroxetine |
| Pediatric | Not recommended | Increased EPS risk; methemoglobinemia in neonates Not FDA-approved for pediatric use | ||
Treatment with metoclopramide should not exceed 12 weeks for any indication. The risk of tardive dyskinesia increases with both duration and cumulative dose. For GERD, duration is determined by endoscopic response (4–12 weeks). For diabetic gastroparesis, 2–8 weeks is typical. If symptoms recur after stopping, carefully weigh the benefit of re-treatment against TD risk. Patients with diabetes are at increased risk for TD.
Pharmacology
Mechanism of Action
Metoclopramide exerts its clinical effects through multiple receptor interactions. As a dopamine D2 receptor antagonist, it blocks dopaminergic signaling in the chemoreceptor trigger zone of the area postrema, producing its central antiemetic effect. Peripherally, D2 receptor antagonism in the gastrointestinal tract, combined with 5-HT4 receptor agonism and sensitization of muscarinic receptors on smooth muscle, underlies its prokinetic action. Metoclopramide increases the tone and amplitude of gastric antral contractions, relaxes the pyloric sphincter and duodenal bulb, and accelerates peristalsis through the duodenum and jejunum. It also raises resting lower esophageal sphincter pressure in a dose-dependent fashion (effects observed from 5 mg, lasting up to 2–3 hours at 20 mg). At higher doses, 5-HT3 receptor antagonism may contribute additional antiemetic activity. The prokinetic effect does not depend on intact vagal innervation but can be abolished by anticholinergic drugs. Metoclopramide has little effect on colonic or gallbladder motility and does not stimulate gastric, biliary, or pancreatic secretions.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Rapidly and well absorbed; Tmax 1–2 h; oral bioavailability 80% ± 15.5% (variable first-pass, range 32–100%) | Administer 30 min before meals to coincide with peak prokinetic activity at mealtime |
| Distribution | Vd ~3.5 L/kg; protein binding ~30%; lipid-soluble; crosses blood–brain barrier | High Vd indicates extensive tissue distribution; CNS penetration underlies both antiemetic efficacy and neuropsychiatric side effects |
| Metabolism | Hepatic via CYP2D6 and N-4 sulphate conjugation; minimal hepatic metabolism in injection PI described as “simple conjugation” | CYP2D6 poor metabolizers and patients on strong CYP2D6 inhibitors require dose reduction; safe in advanced liver disease if renal function is normal |
| Elimination | ~85% excreted in urine within 72 h (half as free or conjugated drug); t½ 5–6 h (normal renal function); clearance reduced ~50% in renal impairment | Dose reduction required when CrCl ≤60 mL/min; dialysis removes relatively little drug |
Side Effects
Metoclopramide has a significant adverse effect profile dominated by CNS and extrapyramidal reactions. The incidence of adverse reactions correlates with dose and duration of therapy.
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Restlessness (akathisia) | ~10% | Motor restlessness with anxiety, agitation, jitteriness, inability to sit still, pacing, and foot tapping; may resolve with dose reduction |
| Drowsiness | ~10% | May impair ability to drive or operate machinery; additive with CNS depressants |
| Fatigue / lassitude | ~10% | CNS depressant effect; may manifest as over-sedation in elderly |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Insomnia | <10% | Less frequent than drowsiness; CNS stimulatory effect in some patients |
| Headache | <10% | May also occur as withdrawal symptom |
| Dizziness | <10% | Also reported during withdrawal |
| Diarrhea | <10% | Related to prokinetic effect on intestinal transit |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Tardive dyskinesia (TD) | Risk increases with duration & dose; higher in elderly women & diabetics | Months of treatment; can occur earlier | Immediately discontinue; no known effective treatment; may be irreversible; do not restart |
| Acute dystonic reactions (torticollis, oculogyric crisis, trismus) | More common at 30–40 mg/day and in adults <30 years | First 24–48 hours | Diphenhydramine 25–50 mg IV/IM or benztropine 1–2 mg IV/IM; discontinue metoclopramide |
| Drug-induced parkinsonism | Dose-dependent | Commonly within first 6 months; can occur later | Discontinue; symptoms generally subside within 2–3 months; do not add antiparkinsonian agents before stopping metoclopramide |
| Neuroleptic malignant syndrome (NMS) | Rare | Any time; especially with concomitant antipsychotics or overdose | Discontinue immediately; intensive supportive care; dantrolene or bromocriptine may be considered |
| Depression with suicidal ideation/suicide | Uncommon | Any time during treatment | Avoid in patients with history of depression; discontinue if depressive symptoms emerge |
| Hyperprolactinemia (galactorrhea, amenorrhea, gynecomastia, impotence) | Uncommon | Weeks to months | Discontinue if clinically significant; check prolactin level |
| Hypertensive crisis (pheochromocytoma) | Very rare (contraindicated in pheochromocytoma) | Minutes after administration | Treat hypertensive emergency; screen for pheochromocytoma; metoclopramide is contraindicated |
| Methemoglobinemia (neonates) | Rare; overdose in neonates | Hours after overdose | Methylene blue; neonates have reduced NADH-cytochrome b5 reductase |
TD presents as involuntary, repetitive, purposeless movements most commonly involving the face and tongue (lip smacking, puckering, chewing, tongue protrusion, grimacing) but can also affect the trunk and extremities. Movements may be choreoathetotic. Metoclopramide itself can mask TD by suppressing the movements, only for them to become apparent upon dose reduction or discontinuation. There is no known effective treatment for established TD. The prescriber must actively screen for early signs at each visit and immediately discontinue metoclopramide at the first sign of involuntary movements.
Drug Interactions
Metoclopramide’s interactions are primarily pharmacodynamic (additive CNS and extrapyramidal effects) and pharmacokinetic (CYP2D6 substrate, altered GI absorption of co-administered drugs due to prokinetic effect).
Monitoring
- Tardive Dyskinesia ScreeningEvery visit; at minimum monthly
RoutineActively assess for involuntary movements of face, tongue, trunk, and extremities at every encounter. Use a standardized tool (AIMS) if available. Discontinue immediately at first sign of TD. Risk increases with duration >12 weeks, higher cumulative dose, elderly age, female sex, and diabetes. - Extrapyramidal SymptomsFirst 48 hours; then ongoing
RoutineAcute dystonia typically occurs within 24–48 hours of starting therapy; parkinsonian symptoms may develop within the first 6 months. Akathisia can occur at any time. Treat acute dystonia with diphenhydramine or benztropine. Discontinue metoclopramide for any EPS. - Mental Status / MoodEach visit
RoutineScreen for depression, suicidal ideation, confusion, and cognitive changes. Avoid use in patients with prior history of depression. Sedation may manifest as confusion and over-sedation in the elderly. - Renal FunctionBaseline; periodically
RoutineClearance reduced ~50% in renal impairment. Reassess creatinine clearance if renal function changes; adjust dose accordingly. Drug substantially excreted by the kidney. - Blood GlucoseOngoing in diabetic patients
Trigger-basedMetoclopramide accelerates gastric emptying, altering the timing of food delivery to the intestine. Insulin dosing or timing may need adjustment to prevent hypoglycemia in diabetic patients using metoclopramide for gastroparesis. - Treatment DurationAt each prescribing encounter
RoutineDo not exceed 12 weeks total. Periodically reassess the need for continued treatment. Document the clinical rationale and patient informed consent regarding TD risk at each renewal.
Contraindications & Cautions
Absolute Contraindications
- History of tardive dyskinesia or dystonic reaction to metoclopramide
- GI conditions where stimulation of motility is dangerous — hemorrhage, mechanical obstruction, or perforation
- Pheochromocytoma or catecholamine-releasing paragangliomas — risk of hypertensive crisis from catecholamine release
- Epilepsy — may increase frequency and severity of seizures
- Hypersensitivity to metoclopramide — laryngeal/glossal angioedema and bronchospasm reported
Relative Contraindications (Specialist Input Recommended)
- Parkinson’s disease — dopamine D2 antagonism may worsen parkinsonian symptoms; avoid use
- History of depression — depression with suicidal ideation reported; avoid use if possible
Use with Caution
- Elderly patients (especially women) — highest risk group for TD; start at 5 mg QID
- Diabetes mellitus — increased TD risk; insulin dosing adjustments may be needed due to altered gastric emptying
- Renal impairment (CrCl ≤60 mL/min) — dose reduction required; risk of toxicity from drug accumulation
- Congestive heart failure or cirrhosis — transient aldosterone increase may cause fluid retention and volume overload
- Hypertension — metoclopramide can release catecholamines; avoid with MAO inhibitors
- NADH-cytochrome b5 reductase deficiency — increased risk of methemoglobinemia
- CYP2D6 poor metabolizers — dose reduction required (same as renal impairment dosing)
Metoclopramide can cause tardive dyskinesia (TD), a serious movement disorder that is often irreversible. There is no known treatment for TD. The risk of developing TD increases with duration of treatment and total cumulative dosage. Discontinue metoclopramide in patients who develop signs or symptoms of TD. In some patients, symptoms may lessen or resolve after metoclopramide is stopped. Avoid treatment with metoclopramide for longer than 12 weeks because of the increased risk of developing TD with longer-term use.
Patient Counselling
Purpose of Therapy
Metoclopramide helps your stomach empty food more quickly and reduces nausea and vomiting. It is prescribed for a limited period — usually no longer than 12 weeks — because of the risk of a serious, potentially permanent side effect affecting involuntary movements.
How to Take
Take metoclopramide 30 minutes before each meal and at bedtime. If using the orally disintegrating tablet (ODT), place it on your tongue and let it dissolve, then swallow. Do not take this medication for longer than your doctor has prescribed.
Sources
- Reglan (metoclopramide) Tablets — FDA-Approved Prescribing Information, revised August 2017. ANI Pharmaceuticals. FDA Label (Tablets)Current FDA-approved label for Reglan tablets; source for indications, boxed warning, dosing tables for GERD and gastroparesis including special population adjustments, and adverse reactions.
- Reglan Injection (metoclopramide injection, USP) — FDA-Approved Prescribing Information, revised 2010. Baxter/ESI Lederle. FDA Label (Injection)FDA-approved label for metoclopramide injection; includes IV/IM dosing for PONV, small bowel intubation, and pharmacokinetic data (Vd 3.5 L/kg, protein binding ~30%, t½ 5–6 h).
- FDA Drug Safety Communication: FDA Requires Boxed Warning and Risk Mitigation Strategy for Metoclopramide-Containing Drugs, 2009. FDA Safety PageFDA communication mandating boxed warning for tardive dyskinesia risk and treatment duration limitation of 12 weeks.
- Parkman HP, Hasler WL, Fisher RS, et al. American Gastroenterological Association technical review on the diagnosis and treatment of gastroparesis. Gastroenterology. 2004;127(5):1592–1622. PubMed: 15521026AGA comprehensive technical review positioning metoclopramide as a first-line prokinetic for gastroparesis with discussion of efficacy evidence and TD risk.
- Rao AS, Camilleri M. Review article: metoclopramide and tardive dyskinesia. Aliment Pharmacol Ther. 2010;31(1):11–19. PubMed: 19886950Key review quantifying the risk of tardive dyskinesia with metoclopramide and identifying risk factors including age, sex, diabetes, and treatment duration.
- Matok I, Gorodischer R, Koren G, et al. The safety of metoclopramide use in the first trimester of pregnancy. N Engl J Med. 2009;360(24):2528–2535. PubMed: 19516033Large Israeli cohort study (over 81,000 deliveries) finding no increased risk of congenital malformations, low birth weight, preterm delivery, or perinatal mortality with first-trimester metoclopramide exposure.
- Camilleri M, Parkman HP, Shafi MA, et al. Clinical Guideline: Management of Gastroparesis. Am J Gastroenterol. 2013;108(1):18–37. PubMed: 23147521ACG clinical guideline recommending metoclopramide as first-line pharmacotherapy for gastroparesis with strong emphasis on limiting treatment duration.
- Gan TJ, Belani KG, Bergese S, et al. Fourth Consensus Guidelines for the Management of Postoperative Nausea and Vomiting. Anesth Analg. 2020;131(2):411–448. PubMed: 32467512Consensus PONV guideline including metoclopramide 25–50 mg as a perioperative antiemetic option with discussion of EPS risk.
- Sanger GJ, Andrews PLR. A History of Drug Discovery for Treatment of Nausea and Vomiting and the Implications for Future Research. Front Pharmacol. 2018;9:913. PubMed: 30233361Historical review of antiemetic pharmacology covering metoclopramide’s role as a D2 antagonist, 5-HT3 antagonist, and 5-HT4 agonist in the context of evolving antiemetic therapy.
- Lee A, Kuo B. Metoclopramide in the treatment of diabetic gastroparesis. Expert Rev Endocrinol Metab. 2010;5(5):653–662. PubMed: 21278804Expert review of metoclopramide’s prokinetic mechanism, clinical efficacy in diabetic gastroparesis, and comparison with alternative prokinetics.
- Bateman DN. Clinical pharmacokinetics of metoclopramide. Clin Pharmacokinet. 1983;8(6):523–529. PubMed: 6360466Foundational PK review: oral bioavailability 32–100% (variable first-pass), clearance reduced ~50% in renal failure, N-4 sulphate conjugation as major metabolic pathway.
- McGovern EM, Grevel J, Bryson SM. Pharmacokinetics of high-dose metoclopramide in cancer patients. Clin Pharmacokinet. 1986;11(6):415–424. PubMed: 3542335PK study of high-dose metoclopramide in oncology patients demonstrating linear kinetics at antiemetic doses and establishing accumulation patterns.
- Ge S, Mendley SR, Gerhart JG, et al. Population Pharmacokinetics of Metoclopramide in Infants, Children, and Adolescents. Clin Transl Sci. 2020;13(6):1189–1198. PubMed: 32324313Population PK study in pediatric patients demonstrating age-dependent clearance and supporting the caution against pediatric use due to variable drug exposure.