COSMEGEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for COSMEGEN (COSMEGEN).
Dactinomycin intercalates between DNA base pairs, inhibiting RNA synthesis and DNA-dependent RNA polymerase. It also causes single-strand DNA breaks via free radical formation and topoisomerase II inhibition.
| Metabolism | Primarily hepatically metabolized via unknown pathways; minimal renal excretion. |
| Excretion | Primarily renal (50-60% as unchanged drug within 24 hours); minor biliary/fecal elimination (approximately 10-20% over 72 hours). |
| Half-life | Terminal half-life 36-48 hours; prolonged to 60-70 hours in severe hepatic impairment. |
| Protein binding | Approximately 90% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Vd 0.2-0.4 L/kg, indicating limited extravascular distribution; largely confined to plasma and extracellular fluid. |
| Bioavailability | Not orally bioavailable (approx. 5% due to degradation in GI tract); dactinomycin must be administered intravenously (100% bioavailability via IV). |
| Onset of Action | IV: Within 1-2 hours for cytotoxic effect; clinical response may be delayed 1-3 weeks. |
| Duration of Action | Duration of myelosuppression typically 1-3 weeks; therapeutic effect persists for weeks to months depending on tumor response. |
| Molecular Weight | 1253.45 |
Intravenous, 15 mcg/kg/day for 5 days, repeated every 3-4 weeks; maximum daily dose 1500 mcg.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment recommended; use with caution if GFR <30 mL/min. |
| Liver impairment | No specific Child-Pugh based guidelines; use with caution in severe impairment. |
| Pediatric use | Same as adult dosing: 15 mcg/kg/day IV for 5 days every 3-4 weeks. |
| Geriatric use | Initiate at lower end of dosing range; monitor renal function and toxicity closely. |
| 1st trimester | Contraindicated due to teratogenicity; associated with fetal malformations and spontaneous abortion. |
| 2nd trimester | Contraindicated; can cause fetal harm and growth retardation. |
| 3rd trimester | Contraindicated; risk of neonatal myelosuppression and other toxicities. |
Clinical note
Comprehensive clinical and safety monograph for COSMEGEN (COSMEGEN).
| Placental transfer | Crosses placenta; demonstrated in animal studies and inferred in humans due to fetal toxicity. |
| Breastfeeding | Excreted in human milk; potential for serious adverse reactions in nursing infants. Discontinue nursing or discontinue drug, taking into account importance of drug to mother. |
| Lactation Rating |
■ FDA Black Box Warning
WARNING: CARCINOGENICITY, EXTRAVASATION, AND HEPATOTOXICITY. Dactinomycin is carcinogenic in animals and should be administered only by experienced physicians. Extravasation causes severe tissue damage. Hepatotoxicity, including veno-occlusive disease, may occur, especially in children under 2 years.
| Serious Effects |
Active infection (especially varicella or herpes zoster)Hypersensitivity to dactinomycin or any componentConcurrent administration with live vaccines
| Precautions | Hepatotoxicity including veno-occlusive disease, extravasation necrosis, myelosuppression, secondary malignancies, immunosuppression, gastrointestinal toxicity, and radiation recall dermatitis. |
| Food/Dietary | No known food interactions. Maintain adequate hydration to prevent complications from tumor lysis syndrome. Avoid alcohol due to potential hepatotoxicity. |
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| L5 |
| Teratogenic Risk | FDA Pregnancy Category D. First trimester: high risk of teratogenicity including craniofacial, skeletal, and visceral malformations. Second and third trimesters: fetal growth restriction, oligohydramnios, and neonatal myelosuppression. |
| Fetal Monitoring | Complete blood counts, liver function tests, renal function tests, and uric acid levels. Fetal ultrasound for growth and amniotic fluid volume. Neonatal monitoring for myelosuppression and infection. |
| Fertility Effects | May cause amenorrhea, ovarian failure, and impaired spermatogenesis. Long-term infertility risk, especially with cumulative doses. |
| Clinical Pearls | 1. Dactinomycin is a potent vesicant; administer via IV push into a free-flowing IV line to minimize extravasation risk. 2. Premedicate with antiemetics as dactinomycin is highly emetogenic. 3. Avoid concurrent use with radiation therapy due to increased risk of radiation recall dermatitis. 4. Monitor hepatic function and bone marrow regularly; dose adjustments may be needed. 5. Protect from light during administration to prevent drug degradation. |
| Patient Advice | Report any pain, redness, or swelling at IV site immediately, as this may indicate tissue damage. · You may experience severe nausea and vomiting; antiemetic medications will be given before treatment. · This drug can lower your blood counts, increasing infection and bleeding risk; avoid crowds and report fever or unusual bruising. · Avoid sun exposure and use sunscreen, as this medication can cause skin sensitivity and radiation recall. · Use effective contraception during and for at least 6 months after treatment due to potential fetal harm. · Notify your doctor if you develop jaundice, dark urine, or abdominal pain as liver problems may occur. |