SAFINAMIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SAFINAMIDE (SAFINAMIDE).
Safinamide is a selective, reversible monoamine oxidase B (MAO-B) inhibitor and a glutamate release inhibitor. It inhibits MAO-B, leading to increased dopamine levels in the striatum, and also modulates glutamate release via use-dependent blockade of voltage-gated sodium channels.
| Metabolism | Primarily metabolized via amide hydrolysis (non-cytochrome P450 dependent), followed by glucuronidation. Minor routes include CYP1A2, CYP3A4, and other enzymes. |
| Excretion | Primarily renal: 76-87% of the dose is excreted in urine as metabolites (mainly safinamide acid and O-demethylated safinamide glucuronide); <5% as unchanged drug. Fecal excretion accounts for 14-23%. |
| Half-life | Terminal elimination half-life is 22-27 hours, allowing once-daily dosing. Steady-state reached within 5-7 days. |
| Protein binding | ~88-90% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Approximately 50-70 L (0.7-1.0 L/kg), indicating distribution into total body water and some tissue binding. |
| Bioavailability | Oral bioavailability is ~95% due to high absorption and minimal first-pass metabolism. Food does not significantly affect absorption. |
| Onset of Action | Oral: Clinical effect (improvement in Parkinson's symptoms) is observed within 1-2 weeks of initiation, though maximum effect may take several weeks. |
| Duration of Action | Duration of action is 24 hours due to once-daily dosing. The effect is maintained over the dosing interval with sustained dopaminergic activity. |
50 mg orally once daily initially; after 2 weeks, may increase to 100 mg once daily. Maximum dose: 100 mg daily.
| Dosage form | TABLET |
| Renal impairment | CrCl < 30 mL/min: not recommended. CrCl 30–49 mL/min: maximum dose 50 mg once daily. CrCl ≥ 50 mL/min: no adjustment. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: not recommended. Child-Pugh C: contraindicated. |
| Pediatric use | Safety and efficacy not established in pediatric patients (<18 years). |
| Geriatric use | No specific dose adjustment recommended; monitor for increased risk of adverse effects due to age-related decline in renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SAFINAMIDE (SAFINAMIDE).
| Breastfeeding | No data on excretion in human milk; M/P ratio unknown. Due to potential for serious adverse reactions in nursing infants, breastfeeding is not recommended during safinamide therapy. |
| Teratogenic Risk | Pregnancy Category C. In animal studies, safinamide produced fetal malformations and embryotoxicity at maternal toxic doses. There are no adequate human studies. Risk cannot be ruled out; use only if potential benefit justifies potential risk. First trimester: unknown risk; avoid unless essential. Second and third trimesters: monitor for potential effects on fetal development; no specific data. |
■ FDA Black Box Warning
None
| Serious Effects |
["Concomitant use of other MAOIs (e.g., linezolid, methylene blue)","Concomitant use of opioids (e.g., meperidine, tramadol, methadone)","Concomitant use of serotonergic drugs (risk of serotonin syndrome)","Concomitant use of sympathomimetics (e.g., amphetamines, pseudoephedrine)","Severe hepatic impairment","Pheochromocytoma"]
| Precautions | ["May cause hypertensive crisis if used with MAOIs or other drugs that increase monoamines","May potentiate serotonin syndrome if used with serotonergic drugs","May cause dyskinesia, hallucinations, or psychotic behavior","Risk of driving impairment","Risk of retinal toxicity (monitor for visual changes)","May exacerbate hypertension","Avoid abrupt discontinuation"] |
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| Fetal Monitoring | Monitor maternal blood pressure, liver function, and signs of serotonin syndrome or dyskinesia. Fetal monitoring via ultrasound for growth and development if used during pregnancy. |
| Fertility Effects | In animal studies, safinamide reduced fertility in males and females at clinically relevant exposures. Human data lacking; potential for reversible impairment of fertility. |