MAREZINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MAREZINE (MAREZINE).
Marezine (cyclizine) is a piperazine-derivative histamine H1-receptor antagonist with central anticholinergic and antiemetic activity. It competitively blocks H1 receptors in the vestibular apparatus and the chemoreceptor trigger zone (CTZ), suppressing nausea and vomiting. It also has antimuscarinic effects on the vomiting center.
| Metabolism | Primarily hepatic via N-demethylation and N-oxidation, involving CYP2D6 and other microsomal enzymes. The major metabolite is norcyclizine, which has some pharmacological activity. |
| Excretion | Renal: 70-80% as unchanged drug and metabolites; fecal: ~20%; biliary: minor |
| Half-life | Terminal elimination half-life is 4-6 hours in adults; prolonged to 8-12 hours in elderly or hepatic impairment |
| Protein binding | Plasma protein binding: 85-90%; primarily to albumin and alpha-1-acid glycoprotein |
| Volume of Distribution | Vd: 3-5 L/kg; indicates extensive tissue distribution, including CNS penetration |
| Bioavailability | Oral: ~40% (due to first-pass metabolism); IM: ~90%; Rectal: ~30-50% |
| Onset of Action | Oral: 30-60 minutes; IM: 20-30 minutes; IV: 5-15 minutes; Rectal: 30-90 minutes |
| Duration of Action | Oral: 4-6 hours; IM: 4-8 hours; IV: 3-6 hours; Rectal: 4-6 hours; duration may be shorter with motion sickness prophylaxis |
50 mg intramuscularly or intravenously every 4 to 6 hours as needed for motion sickness; 50 mg orally 30 to 60 minutes before travel, then every 4 to 6 hours up to 150 mg/24h.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment guidelines for renal impairment; use with caution in severe renal impairment (GFR <30 mL/min) due to potential accumulation. |
| Liver impairment | No formal Child-Pugh based adjustments; use with caution in severe hepatic impairment due to risk of adverse effects. |
| Pediatric use | Children 6–12 years: 25 mg orally or intramuscularly every 6–8 hours, not to exceed 75 mg/24h; <6 years: not recommended. |
| Geriatric use | Start at lower doses (e.g., 25 mg orally every 6–8 hours) due to increased sensitivity, anticholinergic effects, and risk of confusion; avoid in patients with dementia or uncontrolled glaucoma. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MAREZINE (MAREZINE).
| Breastfeeding | Excreted in breast milk; M/P ratio unknown. At therapeutic doses, risk to infant unlikely but monitor for sedation and anticholinergic effects. Caution with high doses or prolonged use. |
| Teratogenic Risk | First trimester: Crosses placenta; limited human data; animal studies show skeletal and CNS defects at high doses; avoid if possible. Second/third trimester: No specific malformation signal; may cause uterine irritability and premature contractions; use only if clearly needed. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to cyclizine or any component of the formulation; acute asthma attack; lower respiratory tract symptoms; premature and full-term neonates (due to risk of CNS depression and respiratory depression); concurrent use with MAOIs or within 14 days of MAOI therapy.
| Precautions | May cause drowsiness; avoid alcohol and other CNS depressants. Use with caution in patients with prostatic hypertrophy, urinary retention, glaucoma, pyloroduodenal obstruction, or asthma. May mask signs of ototoxicity from other drugs. Elderly patients may be more sensitive to anticholinergic effects. Not recommended for use in pregnancy (teratogenicity in animal studies). |
Loading safety data…
| Monitor maternal heart rate, blood pressure, CNS effects (sedation, dizziness). Fetal assessment includes non-stress test and biophysical profile if used near term. Watch for neonatal sedation if given during labor. |
| Fertility Effects | No conclusive evidence of adverse effects on fertility. Anticholinergic effects may theoretically affect ovulation via central mechanisms; no human studies confirm impairment. |