What are the precautions and dosage recommendations for using metoclopramide (Reglan) in patients?

Metoclopramide: Dosing and Precautions

Metoclopramide should be used at a maximum dose of 30 mg/day for no longer than 5 days to minimize the risk of potentially irreversible extrapyramidal symptoms and tardive dyskinesia. 1

Standard Dosing by Indication

Nausea and Vomiting

• Standard dose: 10 mg orally or IV three to four times daily 1, 2
• IV administration: Give slowly over 1-2 minutes for a 10 mg dose to avoid transient anxiety and restlessness 2
• Maximum daily dose: 30 mg/day 1
• Duration: Limit to 5 days maximum 1

Diabetic Gastroparesis

• Oral dosing: 10 mg administered 30 minutes before meals and at bedtime (four times daily) 1
• Severe symptoms: Begin with IM or IV injection 10 mg slowly over 1-2 minutes, may continue up to 10 days before transitioning to oral 2

Chemotherapy-Induced Nausea and Vomiting

• High emetogenic drugs (cisplatin, dacarbazine): 2 mg/kg IV infused over at least 15 minutes, given 30 minutes before chemotherapy, repeated every 2 hours for two doses, then every 3 hours for three doses 2
• Less emetogenic regimens: 1 mg/kg per dose may be adequate 2
• Dilution: Doses exceeding 10 mg should be diluted in 50 mL parenteral solution 2

Prokinetic Use in Cancer Patients

• Early satiety: 40-80 mg/day in divided doses may improve nausea but evidence for appetite improvement is limited 3
• ICU feeding intolerance: 10 mg IV two to three times daily for 24-48 hours as first-line alternative to erythromycin 3

Pregnancy-Related Nausea (Hyperemesis Gravidarum)

• Second-line therapy: Use only after vitamin B6/doxylamine and phenothiazines have failed 3
• Caution: Less drowsiness and dystonia compared to promethazine, but extrapyramidal effects require drug withdrawal 3

Critical Precautions and Contraindications

Neurological Risks

• Extrapyramidal symptoms: Include somnolence, depression, hallucinations, akathisia, tremor, and dystonic reactions 3, 4
• Tardive dyskinesia: Potentially irreversible late dyskinesias can occur, particularly with prolonged use 3
• Long-lasting effects: Even short-term low-dose use (30 mg total over days) has caused severe symptoms lasting 10-13 months including involuntary movements, anxiety, and depression 5
• Acute dystonia management: If occurs, inject 50 mg diphenhydramine IM 2

Cardiovascular Risks

• QT prolongation: Metoclopramide increases QT/RR slope and QT variance, potentially causing ventricular arrhythmias 3, 6, 7
• Monitoring: Evaluate for conduction abnormalities, especially with repeated doses 6
• Catecholamine release: Use cautiously in hypertensive patients as IV administration releases catecholamines 2

Renal Impairment

• Creatinine clearance <40 mL/min: Start at half the standard dose due to primarily renal excretion 6, 2
• Dose adjustment: May increase or decrease based on clinical response and safety 2

Drug Interactions

• Anticholinergics and narcotics: Antagonize metoclopramide's GI motility effects 2
• MAO inhibitors: Use cautiously due to catecholamine release 2
• Insulin/sulfonylureas: May require dose adjustment as metoclopramide affects gastric emptying and can precipitate hypoglycemia 6, 2
• Digoxin: Absorption may be diminished 2
• Oral contraceptives: Absorption may be delayed 6

Absolute Contraindications

• Seizure disorders 1
• Pheochromocytoma 1
• GI bleeding or obstruction: Use with extreme caution 1
• Gut anastomosis: Theoretically could increase pressure on suture lines 2

Special Clinical Situations

Postoperative Use

• Timing: Give IM near end of surgery 2
• Dose: 10 mg standard, up to 20 mg may be used 2
• Consideration: Weigh risk of increased suture line pressure against benefits of avoiding nasogastric suction 2

Radiological Procedures

• Small bowel intubation: Single 10 mg IV dose over 1-2 minutes if tube hasn't passed pylorus in 10 minutes 2
• Pediatric dosing: Ages 6-14 years: 2.5-5 mg; under 6 years: 0.1 mg/kg 2

Hepatic Impairment

• Minimal metabolism: Safe use described in advanced liver disease with normal renal function 2
• Fluid retention risk: Patients with cirrhosis or heart failure may develop volume overload from transient aldosterone increase; discontinue if occurs 2

Administration Considerations

Route-Specific Guidelines

• IV bolus: Always give slowly over 1-2 minutes for 10 mg doses 2
• IV infusion: Dilute and infuse over at least 15 minutes for chemotherapy doses 2
• Oral: Standard tablets 5-20 mg per dose 1

Storage and Compatibility

• Diluted in normal saline: Can be frozen up to 4 weeks 2
• Diluted in D5W: Degrades when frozen; do not use 2
• Light protection: Dilutions may be stored up to 48 hours protected from light, or 24 hours unprotected 2

Key Clinical Pitfalls

• Duration error: Never exceed 5 days of treatment to minimize tardive dyskinesia risk 1
• Dose ceiling: Do not exceed 30 mg/day in routine use 1
• Elderly patients: May require dose reduction due to higher adverse effect risk 1
• Rapid IV push: Causes intense anxiety and restlessness; always give slowly 2
• Diabetic patients: Monitor closely for hypoglycemia and adjust insulin timing 6, 2
• Cardiac patients: Screen for QT prolongation risk factors before use 6, 7