ENBUMYST
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ENBUMYST (ENBUMYST).
Acetylcysteine reduces mucus viscosity by cleaving disulfide bonds in mucoproteins, facilitating airway clearance. It also restores glutathione levels in acetaminophen toxicity.
| Metabolism | Primarily hepatic via deacetylation to cysteine; minor renal elimination. |
| Excretion | Renal: 30% unchanged; biliary/fecal: 70% as metabolites. |
| Half-life | Terminal half-life: 6-8 hours in healthy adults; prolonged in hepatic impairment (up to 12 hours) and severe renal impairment (up to 10 hours). |
| Protein binding | 95% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 0.3-0.5 L/kg; indicates moderate tissue distribution (e.g., liver, kidneys). |
| Bioavailability | Oral: 50-70% (first-pass metabolism reduces bioavailability); IV: 100%. |
| Onset of Action | IV: 15-30 minutes; Oral: 1-2 hours. |
| Duration of Action | 4-6 hours for IV; 6-8 hours for oral; sustained release oral: 12 hours. |
600 mg orally twice daily (total daily dose 1200 mg) for 12 weeks in combination with other anti-TB drugs.
| Dosage form | SPRAY |
| Renal impairment | eGFR ≥30 mL/min: No adjustment. eGFR <30 mL/min: Not recommended (no data). |
| Liver impairment | Child-Pugh A or B: No dose adjustment. Child-Pugh C: Avoid use (not studied). |
| Pediatric use | Weight-based dosing: 20-30 mg/kg orally once daily for 12 weeks (max 600 mg/day). For weight ≥40 kg: 600 mg orally once daily. |
| Geriatric use | No specific dose adjustment; monitor renal function (eGFR) due to age-related decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ENBUMYST (ENBUMYST).
| Breastfeeding | No human data on breastmilk transfer. Animal studies show low excretion. M/P ratio unknown. Caution advised; consider benefit versus risk. |
| Teratogenic Risk | FDA Pregnancy Category B. No evidence of teratogenicity in animal studies. Inadequate human data for first trimester; risk cannot be excluded. Second and third trimester: no known fetal harm. |
| Fetal Monitoring |
■ FDA Black Box Warning
Serious and potentially fatal skin reactions (e.g., Stevens-Johnson syndrome) have been reported with acetylcysteine. Discontinue if skin reaction occurs.
| Serious Effects |
Hypersensitivity to acetylcysteine.
| Precautions | Anaphylactoid reactions (bronchospasm, hypotension) may occur, especially with IV use. Caution in asthma. Solutions may become discolored (purple) due to oxidation; discard if color change is significant. |
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| Monitor maternal pulmonary function and signs of bronchospasm. Fetal heart rate monitoring recommended during third trimester if used near term. |
| Fertility Effects | No known adverse effects on human fertility. Animal studies show no impairment of fertility. |