Topotecan (Page 3 of 5)

6.2 Postmarketing Experience

The following reactions have been identified during postapproval use of topotecan. 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

8.1 Pregnancy

Risk Summary

Based on animal data and its mechanism of action, Topotecan Injection can cause fetal harm when administered to a pregnant woman. There are no available clinical data on the use of topotecan 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.

Data

Animal Data

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.

8.2 Lactation

Risk Summary

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 Injection and for 1 week after the last dose.

Data

Animal Data

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), topotecan was excreted into milk at concentrations up to 48 fold higher than those in plasma.

8.3 Females and Males of Reproductive Potential

Pregnancy Testing

Verify pregnancy status of females of reproductive potential prior to initiating Topotecan Injection [see Use in Specific Populations ( 8.1)].

Contraception

Topotecan Injection can cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1)].

Females

Advise females of reproductive potential to use effective contraception during treatment with Topotecan Injection and for 6 months after the last dose.

Males

Topotecan 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 Injection and for 3 months after the last dose [see Nonclinical Toxicology (13.1)].

Infertility

Females

Topotecan can have both acute and long-term effects on fertility [see Nonclinical Toxicology (13.1)].

Males

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, 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 who received topotecan 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 Injection in patients with a CLcr of 20 to 39 mL/min [see Dosage and Administration (2.6), 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 Injection.

10 OVERDOSAGE

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.

11 DESCRIPTION

Topotecan is a semi-synthetic derivative of camptothecin and a topoisomerase inhibitor. 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 1.25 hydrochloride. It has the molecular formula of C23 H23 N3 O5 •xHCl (x = 1.25) and a molecular weight of 467.02. It is soluble in water and melts with decomposition at 213°C to 218°C.

Topotecan hydrochloride has the following structural formula:

Chemical Structure

Topotecan Injection for intravenous use is supplied as a sterile, non-pyrogenic, clear, light yellow to greenish solution in a single-dose vial at a topotecan free base concentration of 4 mg/4 mL (1 mg/mL).

Each mL contains 1 mg topotecan free base (equivalent to 1.11 mg topotecan hydrochloride), 12 mg of mannitol, USP, and 5 mg of tartaric acid, NF. It may also contain hydrochloric acid and sodium hydroxide to adjust the pH. The solution pH ranges from 2.0 to 2.5.

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.

12.3 Pharmacokinetics

Following administration of topotecan at doses of 0.5 to 1.5 mg/m2 (0.1 to 0.3 times the recommended single agent dose) administered as a 30-minute infusion, the area under the curve (AUC) increases proportionally with dose.

Distribution

Protein binding of topotecan is approximately 35%.

E limination

The terminal half-life of topotecan is 2 to 3 hours following intravenous administration.

Metabolism

Topotecan undergoes a reversible pH-dependent hydrolysis of its pharmacologically active lactone moiety. At pH less than or equal to 4, the lactone is exclusively present, whereas the ring-opened hydroxy-acid form predominates at physiologic pH. Topotecan is metabolized to an N-demethylated metabolite in vitro. The mean metabolite: parent AUC ratio is 3% for total topotecan and topotecan lactone following intravenous administration.

Excretion

The overall recovery of total topotecan and its N-desmethyl metabolite in urine and feces over 9 days averaged 73% ± 2% following an intravenous dose. Mean values (±SD) of 51% (± 3%) as total topotecan and 3% (± 1%) as N-desmethyl topotecan were excreted in the urine. Fecal elimination of total topotecan accounted for 18% (± 4%) while fecal elimination of N-desmethyl topotecan was 1.7% (± 0.6%). An O-glucuronidation metabolite of topotecan and N-desmethyl topotecan has been identified in the urine.

Specific Populations

No clinically significant differences in the pharmacokinetics of topotecan were observed based on age, sex, or hepatic impairment following intravenous administration.

Patients with Renal Impairment

Compared to patients with CLcr (calculated by the Cockcroft-Gault method using ideal body weight) greater than 60 mL/min, plasma clearance of topotecan lactone decreased by 33% in patients with CLcr 40 to 60 mL/min and decreased 65% in patients with CLcr 20 to 39 mL/min. The effect on topotecan pharmacokinetics in patients with CLcr less than 20 mL/min is unknown [see Dosage and Administration (2.6)].

Drug Interaction Studies

Clinical Studies

No clinically significant changes in topotecan pharmacokinetics were observed when coadministered cisplatin with topotecan.

No clinically significant changes in the pharmacokinetics of free platinum were observed in patients coadministered cisplatin with topotecan.

In Vitro Studies

Topotecan does not inhibit CYP1A2, CYP2A6, CYP2C8/9, CYP2C19, CYP2D6, CYP2E, CYP3A, or CYP4A or dihydropyrimidine dehydrogenase.

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