Duration of Action of Reglan (Metoclopramide)
The pharmacological effects of metoclopramide persist for 1 to 2 hours after administration, regardless of route. 1
Pharmacokinetic Profile
The duration of action is distinctly shorter than the elimination half-life, which is an important clinical consideration:
- Pharmacological effect duration: 1-2 hours after any route of administration 1
- Elimination half-life: 5-6 hours in patients with normal renal function 1
- This discrepancy means the drug remains in the body longer than its therapeutic effects last, which has implications for dosing frequency and adverse effect risk 1
Onset of Action by Route
The onset varies significantly by administration route 1:
- Intravenous: 1-3 minutes
- Intramuscular: 10-15 minutes
- Oral: 30-60 minutes
Clinical Implications for Dosing
Standard dosing reflects the short duration of action 2:
- For diabetic gastroparesis: 5-10 mg orally four times daily (QID), administered 30 minutes before meals and at bedtime 2
- For intractable hiccups: 10 mg orally three to four times daily 2
- The four-times-daily dosing schedule is necessary because the 1-2 hour duration of pharmacological effect requires frequent redosing to maintain therapeutic benefit 1
Important Safety Considerations
Despite the short duration of therapeutic action, metoclopramide is generally not intended for long-term use 3:
- Oral preparations are recommended for only 4-12 weeks of therapy 3
- Parenteral metoclopramide should be limited to 1-2 days of use 3
- Extrapyramidal symptoms can occur even with short-term, low-dose treatment and may persist for months after discontinuation 4
- Monitor for extrapyramidal symptoms (dystonic reactions, akathisia, tardive dyskinesia), especially with high doses or prolonged use 2
Renal Impairment Effects
Renal dysfunction significantly prolongs the elimination half-life but does not change the 1-2 hour duration of pharmacological action 1: