Common Brand Names: Reglan
Therapeutic Class: A synthetic substituted benzamide that increases gastric motility and acts as a potent antiemetic.
Common Injectable Dosage Forms:
Injection (as monohydrochloride monohydrate): 5 mg/mL in various vials and ampoules
Dosage in diabetic gastroparesis and GERD is usually initiated at 10 mg four times daily, given 30 minutes before meals and at bedtime, for durations of 2-8 weeks. Parenteral therapy should be stopped when symptoms are suppressed sufficiently to allow oral therapy. For chemotherapy-induced emesis, doses are initiated at 2 mg/kg and given 30 minutes before administration of the agent, then repeated twice at 2-hour intervals. Doses may be continued at 3-hour intervals for 3 more doses if emesis persists, and again for 3 more doses at 1 mg/kg if no response is noted.
For postoperative nausea and vomiting: 10-20 mg doses may be repeated every 4-6 hours as necessary.
In intubation procedures and radiologic exams: 10 mg is usually given as a direct single injection.
Dosages in children for these procedures is generally 0.1 mg/kg when younger than 6 years of age, and 2.5-5 mg in children 6-14 years of age.
Administration and Stability:
May be administered IM, direct IV injection, or by IV infusion. For IM or direct IV injection, the undiluted solution (5 mg/mL) may be used. Direct IV injection is administered slowly over 1-2 minutes. For IV infusion, metoclopramide is diluted with 50 mL of a compatible solution (NS) and slowly over at least 15 minutes. Solutions are stable up to 48 hours when further diluted with compatible solutions, and up to 4 weeks when frozen in NS only. pH 2.5-6.5
Pharmacology/Pharmacokinetics:
The pharmacology of metoclopramide is complex and not fully elucidated, but it is thought to increase gastric motility by several means including increasing amplitude and duration of esophageal contractions, lowered resting tone of esophageal sphincter, and increasing peristalsis of duodenum and jejunum. Metoclopramide is thought to prevent emesis by blocking dopamine receptors in the chemoreceptor trigger zone (CTZ) which controls vomiting response. The drug is 13-22% protein bound and has a volume of distribution of 2-3 L/kg. It is 70-85% excreted in the urine and has an elimination half-life of 3-4 hours.
Drug and Lab Interactions:
May alter the rate and extent of absorption of certain drugs by its effect on transit time in the stomach and small intestine. Concomitant use with other CNS DEPRESSANTS may have additive effects. Effects on GI motility are antagonized by opiate agonists and anticholinergics. May potentiate hypotension when used with hypotensive anesthetic agents.
Contraindications/Precautions:
Contraindicated in patients who receive drugs which cause extrapyramidal symptoms (butyrophenones, phenothiazines), in patients with pheochromocytoma, known hypersensitivity to procainamide (structurally related), or mechanical bowel obstruction and/or perforation. Should be used with caution for prolonged therapy in patients with renal dysfunction, and in patients with mental depression, especially those with suicidal tendencies. Pregnancy Category B.
Monitoring Parameters:
Dystonic reactions, signs of hypoglycemia, agitation, and confusion
Adverse Effects:
The most common side effect is drowsiness, but extrapyramidal effects are often seen with high-dose therapy. Other reported effects include hypotension, diarrhea, galactorrhea, and visual disturbances.
Common Clinical Applications:
Effective in treatment of diabetic gastroparesis, symptomatic gastroesophageal reflux, prevention of chemotherapy-induced nausea and vomiting, small bowel intubation, and radiological exams.
