HYCAMTIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HYCAMTIN (HYCAMTIN).
Topoisomerase I inhibitor; binds to the topoisomerase I-DNA complex and prevents religation of single-strand breaks, leading to DNA damage and cell death.
| Metabolism | Hepatic metabolism via hydrolysis to inactive hydroxyl acid form; also undergoes CYP3A4-mediated metabolism to a lesser extent. |
| Excretion | Renal excretion accounts for approximately 25-50% of the administered dose as unchanged topotecan, with an additional 5-10% as the inactive lactone ring-opened form. Biliary/fecal excretion is minimal (<5%). |
| Half-life | Terminal elimination half-life is approximately 2-3 hours in patients with normal renal function. In patients with moderate renal impairment (CrCl 20-39 mL/min), half-life is prolonged to about 4-5 hours, necessitating dose reduction. |
| Protein binding | Approximately 35% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is approximately 1.2-2.6 L/kg, indicating extensive tissue distribution. The large Vd suggests penetration into tissues including tumors. |
| Bioavailability | Oral bioavailability is approximately 40% (range 30-50%) for the oral capsule formulation, which is dosed at a higher milligram amount to account for incomplete absorption. |
| Onset of Action | Onset of action is not applicable as the drug is not used for acute effects; clinical response is assessed after cycles of therapy (typically every 3-4 weeks). Intravenous administration achieves rapid plasma levels; oral administration reaches peak concentrations at 1-2 hours. |
| Duration of Action | Duration is not well-defined; the drug is given in cycles, with myelosuppression (neutropenia) as a major toxicity peaking at 7-10 days post-dose. Antitumor effects are evaluated after multiple cycles. |
| Action Class | Topoisomerase Inhibitor |
1.5 mg/m2 intravenously over 30 minutes daily for 5 consecutive days, repeated every 21 days.
| Dosage form | CAPSULE |
| Renal impairment | For creatinine clearance 20-39 mL/min: reduce dose to 0.75 mg/m2. For CrCl <20 mL/min: not recommended. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose to 0.75 mg/m2; Child-Pugh C: not recommended. |
| Pediatric use | 0.75 mg/m2 intravenously over 30 minutes daily for 5 days, repeated every 21 days. For solid tumors, may use 1.0 mg/m2. Regimens may vary based on protocol; adjust for renal function. |
| Geriatric use | Monitor renal function more frequently due to age-related decline; start at standard dose if CrCl ≥40 mL/min, otherwise adjust per renal guidelines. Myelosuppression may be more pronounced. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for HYCAMTIN (HYCAMTIN).
| Breastfeeding | It is not known whether topotecan is excreted in human breast milk. Due to the potential for serious adverse reactions in nursing infants (e.g., myelosuppression, gastrointestinal toxicity), breastfeeding is not recommended during treatment and for at least 2 weeks after the last dose. No M/P ratio is available. |
| Teratogenic Risk | Topotecan (HYCAMTIN) is teratogenic in animal studies. In humans, based on its mechanism of action (topoisomerase I inhibitor), it is expected to cause fetal harm if administered during pregnancy. Specifically, first-trimester exposure carries the highest risk for major congenital malformations; second and third trimester exposure may cause fetal growth restriction, myelosuppression, and potential fetal demise. |
■ FDA Black Box Warning
HyCamptin can cause severe myelosuppression (neutropenia, thrombocytopenia, anemia). Administer only in patients with adequate bone marrow reserves. Monitor blood counts frequently.
| Serious Effects |
["Severe hypersensitivity to topotecan or any component of the formulation","Breastfeeding","Severe bone marrow suppression (baseline neutrophil count <1500 cells/mm³, platelet count <100,000 cells/mm³)"]
| Precautions | ["Myelosuppression","Interstitial lung disease","Hypersensitivity reactions","Extravasation (irritant)","Renal impairment (dose adjustment required)","Hepatic impairment"] |
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| Fetal Monitoring | Complete blood counts (CBC) should be monitored weekly during treatment due to risk of myelosuppression. Liver and renal function tests should be checked periodically. In pregnant patients, fetal ultrasound should be considered to assess growth and anatomy if exposure occurs. Monitor for signs of infection, bleeding, and anemia. |
| Fertility Effects | Topotecan can cause gonadal suppression and infertility in both males and females, potentially irreversible. Animal studies have shown impairment of fertility. In humans, amenorrhea and azoospermia may occur. Pre-treatment fertility preservation counseling is recommended. |