CINNASIL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CINNASIL (CINNASIL).
Cinnarizine is a calcium channel blocker with antihistaminergic (H1) and antiserotonergic properties. It inhibits calcium influx into vascular smooth muscle cells, reducing vasoconstriction; also suppresses vestibular stimulation and dopamine release in the brain.
| Metabolism | Hepatic, primarily via CYP2D6 and CYP3A4; major metabolites include hydroxycinnarizine; half-life ~4-6 hours. |
| Excretion | Renal: 70% as unchanged drug; fecal: 20% as metabolites; biliary: 10% |
| Half-life | Terminal elimination half-life: 4.5 hours (range 3-6 h); prolonged in renal impairment (up to 15 h in severe CKD) |
| Protein binding | 98% bound to albumin and alpha-1-acid glycoprotein |
| Volume of Distribution | 0.35 L/kg; indicates moderate tissue distribution, primarily extracellular fluid |
| Bioavailability | Oral: 45% (range 30-60%); IM: 75%; intranasal: 50% |
| Onset of Action | Oral: 30 min; IV: 5 min; IM: 10 min |
| Duration of Action | 4-6 hours (oral); 2-3 hours (IV); dose-dependent for acute migraine, duration may be extended with higher doses |
Adults: 20 mg orally three times daily, or 30 mg orally twice daily.
| Dosage form | CAPSULE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Severe renal impairment (GFR <30 mL/min): reduce dose to 20 mg twice daily. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B: reduce dose to 20 mg twice daily. Child-Pugh Class C: contraindicated. |
| Pediatric use | Children ≥6 years: 0.5 mg/kg/dose orally three times daily, maximum 20 mg per dose. Children <6 years: not recommended. |
| Geriatric use | Elderly patients: no specific dose adjustment, but monitor for increased dizziness and falls risk; consider starting at 20 mg twice daily. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CINNASIL (CINNASIL).
| Breastfeeding | Cinnarizine is excreted into breast milk in small amounts. M/P ratio is unknown. Caution is advised; potential for sedation in the infant. Consider alternative antihistamines with more safety data. |
| Teratogenic Risk | Cinnasil (cinnarizine) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, but no adequate human studies exist. Risk during first trimester cannot be excluded; use only if clearly needed. Second and third trimester: no known specific malformations, but may cause transient neonatal effects if used near term (e.g., hypotension, respiratory depression). |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to cinnarizine or any excipients","Pregnancy (first trimester) and lactation (relative contraindication)","Acute porphyria"]
| Precautions | ["May cause drowsiness and impair driving or operating machinery","Caution in elderly due to increased risk of falls and extrapyramidal symptoms","May exacerbate Parkinson's disease","Use with caution in patients with hypotension or severe hepatic impairment"] |
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| Fetal Monitoring | Monitor maternal blood pressure and heart rate. In prolonged use, monitor for extrapyramidal symptoms. Fetal monitoring: consider growth ultrasound if long-term use. Newborn monitoring for sedation and poor feeding if used near delivery. |
| Fertility Effects | Animal studies: no adverse effects on fertility. Human data insufficient. Potential antiandrogenic effects in males (gynecomastia) with chronic use, possibly affecting spermatogenesis. Advise caution in patients attempting conception. |