What is the recommended dosage of Reglan (metoclopramide) for adults and children, including oral and intravenous routes, and dosing adjustments for renal impairment?

Reglan (Metoclopramide) Dosing

For adults with normal renal function, the standard oral dose of Reglan is 10 mg four times daily (30 minutes before meals and at bedtime), with a maximum treatment duration of 12 weeks; intravenous dosing is 10 mg administered over 1-2 minutes. 1, 2

Adult Dosing by Indication

Gastroesophageal Reflux Disease (GERD)

• Standard dose: 10-15 mg orally four times daily, taken 30 minutes before each meal and at bedtime 1
• Elderly or sensitive patients: May require only 5 mg per dose 1
• Intermittent symptoms: Single doses up to 20 mg may be used prior to provoking situations rather than continuous treatment 1
• Esophageal erosions/ulcerations: 15 mg four times daily is recommended when lesions are present 1

Diabetic Gastroparesis

• Dose: 10 mg orally 30 minutes before each meal and at bedtime 1
• Duration: 2-8 weeks depending on response 1
• Severe symptoms: Initiate with IV metoclopramide injection, then transition to oral when symptoms improve (may require up to 10 days of IV therapy) 1

Adjunctive Therapy for Migraine

• Dose: 10 mg IV or orally, given 20-30 minutes before or with analgesics 3

Pediatric Dosing

Metoclopramide use in children is not well-established with FDA approval, though it has been studied in specific populations. The pharmacokinetics are highly variable in pediatric patients, and a clear concentration-effect relationship has not been established 1, 2.

• Studied doses in cancer patients: 0.22-0.46 mg/kg IV (mean 0.35 mg/kg) over 5 minutes 1, 2
• High-dose antiemetic studies: 2 mg/kg IV, though this carries significant risk of extrapyramidal reactions (15% incidence) 4
• Caution: Children under 5 years should generally avoid metoclopramide due to inability to monitor for visual changes and higher risk of adverse effects 4

Intravenous Administration

• Standard IV dose: 10 mg administered over 1-2 minutes 2
• Onset of action: 1-3 minutes following IV administration 1, 2
• Duration of effect: 1-2 hours 1, 2

Renal Impairment Dosing Adjustments

Metoclopramide clearance is significantly reduced in renal impairment, requiring dose reduction to prevent drug accumulation and toxicity. 1, 2, 5

Dosing by Creatinine Clearance:

• CrCl < 40 mL/min: Initiate therapy at approximately one-half the recommended dosage 1
• Severe renal impairment: Further dose reductions may be necessary based on clinical response 1

Critical consideration: While only 20% of metoclopramide is renally excreted as free drug, total plasma clearance is reduced to approximately 50% of normal in renal failure patients, with prolonged elimination half-life 5, 6. This occurs because nonrenal clearance is also reduced in renal impairment 5.

Hemodialysis:

• No supplemental dosing needed: Hemodialysis contributes minimally to metoclopramide clearance 5
• Metoclopramide losses during dialysis are small compared to total body stores 5

Hepatic Impairment

Metoclopramide undergoes minimal hepatic metabolism (primarily simple conjugation) and can be used safely in patients with advanced liver disease if renal function is normal. 1

Maximum Duration and Safety Limits

• Maximum treatment duration: 12 weeks 1
• Reason for limitation: Risk of tardive dyskinesia increases with prolonged use
• Treatment should not exceed this duration and cannot be recommended beyond 12 weeks 1

Important Clinical Considerations

Pharmacokinetics:

• Oral bioavailability: 80% ± 15.5% 1, 2
• Time to peak (oral): 1-2 hours 1, 2
• Elimination half-life: 5-6 hours in normal renal function 1, 2
• Protein binding: ~30% 1, 2
• Volume of distribution: ~3.5 L/kg 1, 2

Dose-Response Relationship:

• Peak concentrations increase linearly with dose 1, 2
• Akathisia (restlessness) occurs primarily when peak plasma concentrations exceed 100 ng/mL 7
• In children receiving doses ≥2 mg/kg, extrapyramidal reactions occurred in 15% and akathisia in 33% 4

Route of Administration Matters:

The route of administration significantly affects metoclopramide's action on the stomach, with IV administration potentially more effective than oral for certain indications 7.