Topotecan Hydrochloride (Page 3 of 6)
6.2 Postmarketing Experience
The following reactions have been identified during post approval use of topotecan hydrochloride. Because these reactions are reported voluntarily from a population of unknown size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Blood and Lymphatic System: severe bleeding (in association with thrombocytopenia)
Hypersensitivity: allergic manifestations, anaphylactoid reactions, angioedema
Gastrointestinal: abdominal pain potentially associated with neutropenic enterocolitis, gastrointestinal perforation
Pulmonary: interstitial lung disease
Skin and Subcutaneous Tissue: severe dermatitis, severe pruritus
General and Administration Site Conditions: extravasation, mucosal inflammation
8 USE IN SPECIFIC POPULATIONS
Based on animal data and its mechanism of action, topotecan hydrochloride can cause fetal harm when administered to a pregnant woman. There are no available clinical data on the use of topotecan hydrochloride in pregnancy. Topotecan caused embryolethality, fetotoxicity, and teratogenicity in rats and rabbits when administered during organogenesis at doses similar to the clinical dose (see Data). Advise pregnant women of the potential risk to a fetus.
In the U.S. general population, the background risk of major birth defects is 2% to 4% and of miscarriage is 15% to 20% of clinically recognized pregnancies.
In rabbits, an intravenous dose of 0.10 mg/kg/day [about equal to the 1.5 mg/m2 clinical dose based on body surface area (BSA)] given on Days 6 through 20 of gestation caused maternal toxicity, embryolethality and reduced fetal body weight. In the rat, an intravenous dose of 0.23 mg/kg/day (about equal to the 1.5 mg/m2 clinical dose based on BSA) given for 14 days before mating through gestation Day 6 caused fetal resorption, microphthalmia, pre-implant loss, and mild maternal toxicity. Administration of an intravenous dose of 0.10 mg/kg/day (about half the 1.5 mg/m2 clinical dose based on BSA) given to rats on Days 6 through 17 of gestation caused an increase in post-implantation mortality. This dose also caused an increase in total fetal malformations. The most frequent malformations were of the eye (microphthalmia, anophthalmia, rosette formation of the retina, coloboma of the retina, ectopic orbit), brain (dilated lateral and third ventricles), skull, and vertebrae.
There are no data on the presence of topotecan or its metabolites in human milk or their effects on the breastfed infant or on milk production. Lactating rats excrete high concentrations of topotecan in milk (see Data). Because of the potential for serious adverse reactions in breastfed infants, advise women not to breastfeed during treatment with topotecan hydrochloride for injection and for 1 week after the last dose.
Following intravenous administration of topotecan to lactating rats at a dose of 4.72 mg/m2 (about twice the 1.5 mg/m2 clinical dose based on BSA) to lactating rats, topotecan was excreted into milk at concentrations up to 48-fold higher than those in plasma.
8.3 Females and Males of Reproductive Potential
Verify pregnancy status of females of reproductive potential prior to initiating topotecan hydrochloride for injection [see Use in Specific Populations ( 8.1)].
Topotecan hydrochloride can cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1)].
Advise females of reproductive potential to use effective contraception during treatment with topotecan hydrochloride for injection and for 6 months after the last dose.
Topotecan hydrochloride may damage spermatozoa, resulting in possible genetic and fetal abnormalities. Advise males with a female partner of reproductive potential to use effective contraception during treatment with topotecan hydrochloride for injection and for 3 months after the last dose [see Nonclinical Toxicology (13.1)].
Topotecan hydrochloride can have both acute and long-term effects on fertility [see Nonclinical Toxicology (13.1)].
Effects on spermatogenesis occurred in animals administered topotecan [see Nonclinical Toxicology (13.1)].
8.4 Pediatric Use
Safety and effectiveness in pediatric patients have not been established.
8.5 Geriatric Use
Of the 879 patients with metastatic ovarian cancer or small cell lung cancer in clinical trials of topotecan hydrochloride for injection, 32% were aged 65 years and older, while 3.8% were aged 75 years and older. Of the 140 patients with Stage IV-B, relapsed, or refractory cervical cancer in clinical trials of topotecan hydrochloride for injection who received topotecan hydrochloride with cisplatin in the randomized clinical trial, 6% were aged 65 years and older, while 3% were aged 75 years and older. No overall differences in effectiveness or safety were observed between these patients and younger patients and other reported clinical experience has not identified differences in responses between the elderly and younger patients.
8.6 Renal Impairment
Reduce the dose of topotecan hydrochloride for injection in patients with a CLcr of 20 to 39 mL/min [see Dosage and Administration (2.4), Clinical Pharmacology (12.3)]. No dosage adjustment is recommended for patients with CLcr greater than or equal to 40 mL/min. Insufficient data are available in patients with CLcr less than 20 mL/min to provide a dosage recommendation for topotecan hydrochloride for injection.
Overdoses (up to 10-fold of the recommended dose) have occurred in patients receiving intravenous topotecan. The primary complication of overdosage is myelosuppression. Elevated hepatic enzymes, mucositis, gastrointestinal toxicity, and skin toxicity have occurred with overdosages. If an overdose is suspected, monitor the patient closely for myelosuppression and institute supportive-care measures as appropriate.
Topotecan hydrochloride is a semi-synthetic derivative of camptothecin and is an anti-tumor drug with topoisomerase I-inhibitory activity. The chemical name for topotecan hydrochloride is (S)-10-[(dimethylamino)methyl]-4-ethyl-4,9-dihydroxy-1H -pyrano[3’,4’:6,7] indolizino [1,2-b ]quinoline-3,14-(4H ,12H)-dione monohydrochloride. It has the molecular formula C23 H23 N3 O5 •HCl and a molecular weight of 457.9. It is soluble in water and melts with decomposition at 213°C to 218°C.
Topotecan hydrochloride has the following structural formula:
Topotecan Hydrochloride for Injection is supplied as a sterile, lyophilized, buffered, light yellow to greenish powder available in single-dose vials. Each vial contains topotecan hydrochloride equivalent to 4 mg of topotecan as free base. The reconstituted solution ranges in color from yellow to yellow-green and is intended for administration by intravenous infusion.
Inactive ingredients are mannitol, 48 mg, and tartaric acid, 20 mg. Hydrochloric acid and sodium hydroxide may be used to adjust the pH. The solution pH ranges from 2.8 to 3.2.
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action
Topoisomerase I relieves torsional strain in DNA by inducing reversible single-strand breaks. Topotecan binds to the topoisomerase I-DNA complex and prevents re-ligation of these single-strand breaks. The cytotoxicity of topotecan is thought to be due to double-strand DNA damage produced during DNA synthesis, when replication enzymes interact with the ternary complex formed by topotecan, topoisomerase I, and DNA. Mammalian cells cannot efficiently repair these double-strand breaks.
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