Therapeutic Effects: aspiration prophylactic, antiemetic

Anesthesia Implications

Used primarily for aspiration prophylaxis. The goal is to increase the stomach contents Ph to > 2.5 and to reduce the stomach content volume to < 25 ml. Metoclopramide is used to reduce the stomach content volume.

Metoclopramide also increases barrier pressure by increasing lower esophageal sphincter tone (reduces chances of reflux).

The typical IV dose listed below will reduce the stomach contents by about 50%

Metoclopramide may be ineffective in patients who have received an opioid or atropine prior to administration.

Often given with H2 antagonists such as ranitidine. Ranitidine would reduce the stomach content acidity, while metoclopramide would empty the stomach. Both drugs together may have additive effects.

As effective as phenergan in reducing the incidence of nausea and vomiting

Inhibits plasma cholinesterase (prolongs the affects of succinylcholine and mivacurium)

Some sedating properties. However, it is considered nonsedating in contrast to other anti-emetics like phenergan.

Increases cyclosporine blood levels

Prolongs succinylcholine neuromuscular blockade by 135 – 228% by inhibition of plasma cholinesterase

OB:
Crosses the placenta, but studies show that there is no significant effect on the fetus or neonate

Literature suggests using metoclopramide, dimenhydrinate, and ondansetron as 1st, 2nd, and 3rd line agents respectively for PONV prophylaxis. Optimal times to administer are prior to surgery or after umbilical cord clamping.

Women who received both meperidine and metoclopramide had slightly better pain scores than women who received meperidine alone.
Prokinetic effects are the same between pregnant and nonpregnant women.

Reduces pain scores and need for Nitrous Oxide in parturients during labor.

If given prior to spinal anesthesia or after delivery of the baby, metoclopramide has shown to significantly reduce intraoperative and PONV.

Rapidly induces hyperprolactinemia, which will impair ovarian follicle maturation and the function of the corpus luteum. While documented as acceptable to give immediately before oocyte retrieval, uterine receptivity to the embryo may be negatively affected (infertility) if it is given routinely after retrieval.

Contraindications

Parkinsons Disease – Should be avoided as it will work against the dopamine agonists used to treat the condition
Pheochromocytoma – Should be avoided in these patients as it is associated with the release of catecholamines from the tumor
“Black box” warning that this agent can cause prolongation of the Q-T interval and torsades de pointes. Avoid in patients at risk who have a prolonged Q-T interval or those already at risk for dysrhythmias.
Potential for extrapyramidal effects

IV push dose

Adult textbook dose: 0.15 – 0.20 mg/kg
Typical dose: 5-10 mg, 15 – 30 min prior to surgery. Give over 3-5 minutes to prevent abdominal cramping, restlessness, and anxiety

Typical PO dose: 10 mg 30-60 minutes before surgery.

Classification: Dopamine antagonist, Procainamide derivative

Time to Onset: 15 minutes

Time to Peak: 30-40 minutes

Duration: Elimination half-life 2-4 hours

Method of Action: gastric prokinetic: Increases gastroesophageal sphincter tone. Reduces gastric volume by increasing upper gastric peristalsis. relaxes the pylorus and duodenum. Antagonizes dopamine in the chemoreceptor trigger zone (CTZ).

Additional Notes:
The only drug with FDA approval for the treatment of diabetic gastroparesis