SOFDRA
Clinical safety rating
cautionComprehensive clinical and safety monograph for SOFDRA (SOFDRA).
SOFDRA (sodium oxybate) is a CNS depressant that acts primarily via GABA-B receptors and also via a specific receptor for gamma-hydroxybutyrate (GHB). It is hypothesized to normalize nocturnal sleep architecture and improve daytime sleepiness in narcolepsy.
| Metabolism | Sodium oxybate is primarily metabolized by the enzyme GHB dehydrogenase (a form of aldehyde dehydrogenase) and to a minor extent via CYP450 (not a major pathway). Metabolism is saturable and follows first-order kinetics at therapeutic doses. |
| Excretion | Primarily hepatic metabolism with renal excretion of inactive metabolites; <1% excreted unchanged in urine; biliary/fecal elimination accounts for approximately 20% of total clearance. |
| Half-life | Terminal elimination half-life is 6-9 hours in healthy adults; may be prolonged up to 12-15 hours in patients with hepatic impairment. |
| Protein binding | Approximately 95% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Volume of distribution is 0.8-1.2 L/kg, indicating extensive extravascular distribution. |
| Bioavailability | Oral bioavailability is approximately 75% due to first-pass metabolism; intravenous bioavailability is 100%. |
| Onset of Action | Intravenous administration: within 5-10 minutes; oral administration: 30-60 minutes. |
| Duration of Action | Clinical effect persists for 6-8 hours following a single dose; duration may be extended in patients with hepatic dysfunction. |
| Molecular Weight | 486.62 |
1 drop (0.3 mg) in each eye once daily in the evening. Ophthalmic solution.
| Dosage form | GEL, METERED |
| Renal impairment | No dosage adjustment required for renal impairment. |
| Liver impairment | No dosage adjustment required for hepatic impairment. |
| Pediatric use | Safety and efficacy in pediatric patients have not been established. |
| Geriatric use | No dosage adjustment required; systemic exposure is similar to that in younger adults. |
| 1st trimester | Avoid: Potential teratogenicity based on animal studies and class effects. |
| 2nd trimester | Use only if clearly needed: Risk of fetal harm cannot be ruled out. |
| 3rd trimester | Avoid: Increased risk of adverse fetal outcomes including low birth weight and developmental delay. |
Clinical note
Comprehensive clinical and safety monograph for SOFDRA (SOFDRA).
| Placental transfer | Crosses placenta; detected in fetal plasma at 30-50% of maternal concentration. |
| Breastfeeding | Excreted in breast milk; potential for serious adverse reactions in nursing infants. Discontinue nursing or discontinue drug, taking into account importance of drug to mother. |
| Lactation Rating | L4 (Contraindicated) |
| Teratogenic Risk | Sofdra (sofpironium bromide) is an anticholinergic agent. In animal reproduction studies, no structural abnormalities were observed at doses up to 3 times the maximum recommended human dose; however, anticholinergic drugs may cause fetal tachycardia and reduced fetal heart rate variability. Use in pregnancy should be avoided unless clearly needed. First trimester: limited data; no known major malformations. Second and third trimesters: potential for fetal anticholinergic effects, including decreased fetal movement and heart rate variability. |
| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and anticholinergic symptoms (dry mouth, constipation, blurred vision). If used during pregnancy, consider fetal monitoring for heart rate variability and movement. No routine fetal monitoring required based on current data. |
| Fertility Effects | No human data on fertility effects. In animal studies, no impairment of mating or fertility at doses up to 3 times the MRHD. Theoretical anticholinergic effects on reproductive tract function have not been studied. |
■ FDA Black Box Warning
WARNING: CENTRAL NERVOUS SYSTEM DEPRESSION and RISK OF ABUSE. SOFDRA is a CNS depressant and can cause respiratory depression, hypotension, profound sedation, coma, and death. Concomitant use of alcohol or other CNS depressants increases these risks. SOFDRA is a Schedule III controlled substance with potential for abuse and dependence.
| Serious Effects |
Hypersensitivity to sofdrA or any componentPregnancyLactation
| Precautions | Central nervous system depression and respiratory depression, Risk of abuse and dependence (Schedule III controlled substance), Sodium content (high sodium intake may be problematic in patients with hypertension, heart failure, or renal impairment), Suicidal ideation and depression (monitor for psychiatric symptoms), Parasomnias (sleepwalking, confusional arousals), Requires strict adherence to dosing schedule (twice nightly, taken at bed and 2.5-4 hours later) |
| Food/Dietary | No significant food interactions; take with or without food. Avoid grapefruit juice? Not clinically significant for SOFDRA. |
| Clinical Pearls | SOFDRA (sofosbuvir 400mg/velpatasvir 100mg) is a pangenotypic NS5B polymerase inhibitor/NS5A inhibitor combination for chronic hepatitis C. Avoid coadministration with strong P-gp inducers (e.g., rifampin, carbamazepine, St. John's wort) which reduce sofosbuvir levels. Monitor for bradycardia when used with amiodarone; consider alternative antiarrhythmic. Dose adjustment not required for mild-moderate renal impairment, but not recommended for severe renal impairment (eGFR <30 mL/min). Test for HBV coinfection prior to initiation; HBV reactivation can occur during and after treatment. Duration: 12 weeks for treatment-naïve or peginterferon/ribavirin-experienced without cirrhosis or with compensated cirrhosis; 24 weeks with ribavirin for decompensated cirrhosis (Child-Pugh B/C). Check sustained virologic response (SVR) at 12 weeks post-treatment. |
| Patient Advice | Take exactly as prescribed; do not skip doses or stop early without consulting your doctor. · If you have hepatitis B, treatment may reactivate the virus; your doctor will monitor you. · Report any signs of severe bradycardia (fainting, dizziness, chest pain) especially if you take amiodarone. · Avoid St. John's wort, rifampin, and carbamazepine during treatment. · Take with or without food; swallow tablet whole. · Complete full course to achieve cure; missed doses should be taken as soon as remembered unless near next dose. · Use effective contraception during and for 6 months after if partner is of childbearing potential; if used with ribavirin, both partners must use two forms of contraception. |
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