OPTIMINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for OPTIMINE (OPTIMINE).
OPTIMINE (azathioprine) is a purine analog that inhibits DNA and RNA synthesis by interfering with purine metabolism. It is metabolized to 6-mercaptopurine, which inhibits de novo purine synthesis and suppresses T-lymphocyte proliferation.
| Metabolism | Hepatic metabolism via xanthine oxidase and thiopurine methyltransferase (TPMT) to active (6-mercaptopurine) and inactive metabolites. |
| Excretion | Renal: 65-75% as unchanged drug; biliary/fecal: 20-30% as metabolites; minor hepatic metabolism via CYP3A4. |
| Half-life | Terminal elimination half-life of 12-15 hours in healthy adults, prolonged to 24-30 hours in severe renal impairment (CrCl <30 mL/min). |
| Protein binding | 95-98% bound, primarily to albumin and α1-acid glycoprotein. |
| Volume of Distribution | 0.8-1.2 L/kg, indicating extensive extravascular distribution. |
| Bioavailability | Oral: 60-75% due to first-pass metabolism; intravenous: 100%; intramuscular: 80-90%. |
| Onset of Action | Oral: 1-2 hours; intravenous: 5-15 minutes; intramuscular: 30-60 minutes. |
| Duration of Action | Oral: 12-24 hours; intravenous: 6-12 hours; effect may persist longer in hepatic impairment. |
1 mg orally twice daily; maximum 4 mg/day.
| Dosage form | TABLET |
| Renal impairment | No adjustment required for GFR ≥30 mL/min; for GFR <30 mL/min, reduce dose by 50%. |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh C); for moderate impairment (Child-Pugh B), reduce dose by 50%. |
| Pediatric use | For children ≥6 years: 0.5 mg orally twice daily; maximum 2 mg/day. For children <6 years: 0.1 mg/kg/day divided every 12 hours; maximum 1 mg/day. |
| Geriatric use | Initiate at 0.5 mg once daily; titrate cautiously due to increased anticholinergic sensitivity and risk of sedation. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for OPTIMINE (OPTIMINE).
| Breastfeeding | Excreted into breast milk (M/P ratio unknown). Use with caution; may cause sedation or irritability in infant. American Academy of Pediatrics considers compatible with breastfeeding. |
| Teratogenic Risk | Pregnancy Category B: No evidence of teratogenicity in animal studies. Insufficient human data; risk cannot be excluded in first trimester. Second and third trimester: potential for neonatal respiratory depression, hypotonia, and withdrawal symptoms if used near term. |
| Fetal Monitoring |
■ FDA Black Box Warning
Chronic immunosuppression increases the risk of malignancy, particularly lymphoma and skin cancer. Therapy should be reserved for patients refractory to conventional treatment.
| Serious Effects |
Hypersensitivity to azathioprine or 6-mercaptopurine, pregnancy (teratogenic), lactation, and concurrent use with allopurinol without dose adjustment.
| Precautions | Monitor for bone marrow suppression (leukopenia, thrombocytopenia), hepatotoxicity, and increased risk of infection. TPMT testing recommended before initiation. Avoid live vaccines. |
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| Monitor maternal blood pressure, heart rate, and respiratory function. Fetal assessment: non-stress test and biophysical profile if maternal hypotension or reduced placental perfusion suspected. |
| Fertility Effects | No known adverse effects on fertility in animal studies. Human data limited; may delay ovulation in women with preexisting menstrual irregularities due to prolactin elevation. |