TOPOTECAN HYDROCHLORIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TOPOTECAN HYDROCHLORIDE (TOPOTECAN HYDROCHLORIDE).
Topoisomerase I inhibitor; binds to topoisomerase I-DNA complex, prevents religation of single-strand breaks, leading to DNA damage and apoptosis.
| Metabolism | Hepatic via glucuronidation; minor CYP3A4, CYP1A2; undergoes hydrolysis to inactive lactone ring-opened form. |
| Excretion | Renal excretion accounts for approximately 30% of total clearance as unchanged drug. Biliary/fecal excretion is minor, with less than 2% recovered in feces. The remainder is metabolized primarily via lactone ring hydrolysis to a less active hydroxy acid form, which is also renally eliminated. |
| Half-life | Terminal elimination half-life is approximately 2-3 hours in patients with normal renal function. In patients with moderate renal impairment (creatinine clearance 20-39 mL/min), half-life is prolonged to about 5 hours, requiring dose adjustment. |
| Protein binding | 35% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is approximately 0.3-0.6 L/kg (range 20-40 L/m² in adults), indicating moderate tissue distribution with some penetration into body tissues including tumors. |
| Bioavailability | Oral bioavailability is approximately 30-40% (range 32-45%) in patients with solid tumors; however, the drug is primarily administered intravenously due to high interpatient variability and dose-limiting gastrointestinal toxicity. |
| Onset of Action | Intravenous administration: Onset of antitumor effect is variable, typically observed within days to weeks depending on tumor type and dosing schedule. No immediate clinical effect. |
| Duration of Action | Duration of myelosuppression (neutropenia) is typically 7-10 days, nadir at day 8-11. Recovery usually by day 21. Clinical antitumor effect duration varies with response. |
1.5 mg/m² intravenously over 30 minutes daily for 5 consecutive days, repeated every 21 days.
| Dosage form | INJECTABLE |
| Renal impairment | For creatinine clearance 20-39 mL/min: reduce dose to 0.75 mg/m². For clearance <20 mL/min: insufficient data; avoid use or use with extreme caution. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B: reduce dose to 0.75 mg/m². Child-Pugh Class C: not recommended. |
| Pediatric use | Safety and efficacy not established in pediatric patients; no specific dosing guidelines available. |
| Geriatric use | Elderly patients may have reduced renal function; monitor creatinine clearance carefully. Dose adjustment for renal impairment applies; no specific geriatric dose beyond renal adjustment. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TOPOTECAN HYDROCHLORIDE (TOPOTECAN HYDROCHLORIDE).
| Breastfeeding | No human data available; M/P ratio unknown. Based on molecular weight (low) and lipophilicity, expected to distribute into breast milk. Discontinue breastfeeding during therapy and for at least 2 weeks after last dose due to potential severe adverse effects in infants. |
| Teratogenic Risk | Pregnancy Category D. First trimester: high risk of teratogenicity (neural tube defects, skeletal anomalies) based on animal studies and its mechanism (topoisomerase I inhibitor). Second/third trimesters: risk of fetal growth restriction, oligohydramnios, and preterm labor. Exposure at any trimester may cause fetal harm. |
■ FDA Black Box Warning
Bone marrow suppression (neutropenia, thrombocytopenia, anemia) is dose-limiting; can be severe and fatal. Administer only under supervision of physician experienced in chemotherapy.
| Serious Effects |
Hypersensitivity to topotecan or any component; severe bone marrow depression; breastfeeding.
| Precautions | Myelosuppression (monitor blood counts), interstitial lung disease, diarrhea, extravasation, hepatotoxicity, renal impairment, pregnancy category D. |
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| Fetal Monitoring | Monitor maternal complete blood count (CBC) with differential weekly due to myelosuppression. Assess hepatic and renal function baseline and periodically. Fetal monitoring: ultrasound for growth and amniotic fluid volume if used in pregnancy. Monitor for signs of infection, bleeding, or anemia. |
| Fertility Effects | May cause ovarian failure and reduced fertility in females based on animal studies and its mechanism (inhibits rapidly dividing cells). Males may experience oligospermia or azoospermia. Fertility effects may be irreversible. |