Azacitidine (Page 3 of 5)

6.2 Postmarketing Experience

The following adverse reactions have been identified during postmarketing use of azacitdine for injection. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

  • Interstitial lung disease
  • Tumor lysis syndrome
  • Injection site necrosis
  • Sweet’s syndrome (acute febrile neutrophilic dermatosis)
  • Necrotizing fasciitis (including fatal cases)
  • Differentiation syndrome

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

Risk Summary

Based on its mechanism of action and findings in animals, azacitidine for injection can cause fetal harm when administered to a pregnant woman [see Clinical Pharmacology (12.1)]. There are no data on the use of azacitidine in pregnant women. Azacitidine was teratogenic and caused embryo-fetal lethality in animals at doses lower than the recommended human daily dose (see Data). Advise pregnant women of the potential risk to the fetus.

The background rate of major birth defects and miscarriage is unknown for the indicated population. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Data

Animal Data

Early embryotoxicity studies in mice revealed a 44% frequency of intrauterine embryonal death (increased resorption) after a single IP (intraperitoneal) injection of 6 mg/m2 (approximately 8% of the recommended human daily dose on a mg/m2 basis) azacitidine on gestation day 10. Developmental abnormalities in the brain have been detected in mice given azacitidine on or before gestation day 15 at doses of ~3 to 12 mg/m2 (approximately 4% to 16% the recommended human daily dose on a mg/m2 basis).

In rats, azacitidine was clearly embryotoxic when given IP on gestation days 4 to 8 (postimplantation) at a dose of 6 mg/m2 (approximately 8% of the recommended human daily dose on a mg/m2 basis), although treatment in the preimplantation period (on gestation days 1 to 3) had no adverse effect on the embryos. Azacitidine caused multiple fetal abnormalities in rats after a single IP dose of 3 to 12 mg/m2 (approximately 8% the recommended human daily dose on a mg/m2 basis) given on gestation day 9, 10, 11 or 12. In this study azacitidine caused fetal death when administered at 3 to 12 mg/m2 on gestation days 9 and 10; average live animals per litter was reduced to 9% of control at the highest dose on gestation day 9. Fetal anomalies included: CNS anomalies (exencephaly/encephalocele), limb anomalies (micromelia, club foot, syndactyly, oligodactyly), and others (micrognathia, gastroschisis, edema, and rib abnormalities).

8.2 Lactation

Risk Summary

There is no information regarding the presence of azacitidine in human milk, the effects of azacitidine for injection on the breastfed infant, or the effects of azacitidine for injection on milk production. Because many drugs are excreted in human milk and because of the potential for tumorigenicity shown for azacitidine in animal studies [see Nonclinical Toxicology (13.1)] and the potential for serious adverse reactions in nursing infants from azacitidine for injection, advise patients not to breastfeed during treatment with azacitidine for injection.

8.3 Females and Males of Reproductive Potential

Based on its mechanism of action and findings in animals, azacitidine for injection can cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1)].

Pregnancy Testing

Verify the pregnancy status of females of reproductive potential prior to initiating azacitidine for injection.

Contraception

Females

Advise females of reproductive potential to avoid pregnancy during treatment with azacitidine for injection.

Males

Males with female sexual partners of reproductive potential should not father a child and should use effective contraception during treatment with azacitidine for injection.

Infertility

Based on animal data, azacitidine could have an effect on male or female fertility [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 total number of patients in Studies 1, 2 and 3, 62% were 65 years and older and 21% were 75 years and older. No overall differences in effectiveness were observed between these patients and younger patients. In addition there were no relevant differences in the frequency of adverse reactions observed in patients 65 years and older compared to younger patients.

Of the 179 patients randomized to azacitidine in Study 4, 68% were 65 years and older and 21% were 75 years and older. Survival data for patients 65 years and older were consistent with overall survival results. The majority of adverse reactions occurred at similar frequencies in patients < 65 years of age and patients 65 years of age and older.

Elderly patients are more likely to have decreased renal function. Monitor renal function in these patients [see Dosage and Administration (2.5) and Warnings and Precautions (5.3)].

10 OVERDOSAGE

One case of overdose with azacitidine for injection was reported during clinical trials. A patient experienced diarrhea, nausea, and vomiting after receiving a single intravenous dose of approximately 290 mg/m2 , almost 4 times the recommended starting dose. The events resolved without sequelae, and the correct dose was resumed the following day. In the event of overdosage, the patient should be monitored with appropriate blood counts and should receive supportive treatment, as necessary. There is no known specific antidote for azacitidine for injection overdosage.

11 DESCRIPTION

Azacitidine for injection contains azacitidine, which is a pyrimidine nucleoside analog of cytidine. Azacitidine is 4-amino-1-β-D-ribofuranosyl-1,3,5-triazin-2(1H)-one. The structural formula is as follows:

structure

The empirical formula is C8 H12 N4 O5 . The molecular weight is 244.20. Azacitidine is a white to off- white powder. Azacitidine was found to be soluble in dimethyl sulphoxide, sparingly soluble in water and insoluble in acetone and ethanol.

The finished product is supplied in a sterile form for reconstitution as a suspension for subcutaneous injection or reconstitution as a solution with further dilution for intravenous infusion. Vials of azacitidine for injection contain 100 mg of azacitidine and 100 mg mannitol as a sterile lyophilized powder.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Azacitidine for injection is a pyrimidine nucleoside analog of cytidine. Azacitidine for injection is believed to exert its antineoplastic effects by causing hypomethylation of DNA and direct cytotoxicity on abnormal hematopoietic cells in the bone marrow. The concentration of azacitidine required for maximum inhibition of DNA methylation in vitro does not cause major suppression of DNA synthesis. Hypomethylation may restore normal function to genes that are critical for differentiation and proliferation. The cytotoxic effects of azacitidine cause the death of rapidly dividing cells, including cancer cells that are no longer responsive to normal growth control mechanisms. Non-proliferating cells are relatively insensitive to azacitidine.

12.3 Pharmacokinetics

The pharmacokinetics of azacitidine were studied in 6 MDS patients following a single 75 mg/m2 subcutaneous dose and a single 75 mg/m2 intravenous dose.

Absorption

Azacitidine is rapidly absorbed after subcutaneous administration; the peak plasma azacitidine concentration of 750 ± 403 ng/ml occurred in 0.5 hour.

Distribution

The bioavailability of subcutaneous azacitidine relative to intravenous azacitidine is approximately 89%, based on area under the curve. Mean volume of distribution following intravneous dosing is 76 ± 26 L. Mean apparent subcutaneous clearance is 167 ± 49 L/hour and mean half-life after subcutaneous administration is 41 ± 8 minutes. The AUC and Cmax of subcutaneous administration of azacitidine in 21 patients with cancer were approximately dose proportional within the 25 to 100 mg/m2 dose range. Multiple dosing at the recommended dose-regimen does not result in drug accumulation.

Elimination

Published studies indicate that urinary excretion is the primary route of elimination of azacitidine and its metabolites. Following intravenous administration of radioactive azacitidine to 5 cancer patients, the cumulative urinary excretion was 85% of the radioactive dose. Fecal excretion accounted for <1% of administered radioactivity over 3 days. Mean excretion of radioactivity in urine following subcutaneous administration of 14 C-azacitidine was 50%. The mean elimination half-lives of total radioactivity (azacitidine and its metabolites) were similar after intravenous and subcutaneous administrations, about 4 hours.

Specific Populations

In patients with cancer the pharmacokinetics of azacitidine in 6 patients with normal renal function (CLcr > 80 mL/min) and 6 patients with severe renal impairment (CLcr < 30 mL/min) were compared following daily subcutaneous dosing (Days 1 through 5) at 75 mg/m2 /day. Severe renal impairment increased azacitidine exposure by approximately 70% after single and 41% after multiple subcutaneous administrations. This increase in exposure was not correlated with an increase in adverse events. The exposure was similar to exposure in patients with normal renal function receiving 100 mg/m2. Therefore, a Cycle 1 dose modification is not recommended. The effects of hepatic impairment, gender, age, or race on the pharmacokinetics of azacitidine have not been studied.

Drug-Drug Interactions

No formal clinical drug interaction studies with azacitidine have been conducted.

An in vitro study of azacitidine incubation in human liver fractions indicated that azacitidine may be metabolized by the liver. Whether azacitidine metabolism may be affected by known microsomal enzyme inhibitors or inducers has not been studied.

An in vitro study with cultured human hepatocytes indicated that azacitidine at concentrations up to 100 μM (IV Cmax = 10.6 μM) does not cause any inhibition of CYP2B6 and CYP2C8. The potential of azacitidine to inhibit other cytochrome P450 (CYP) enzymes is not known.

In vitro studies with human cultured hepatocytes indicate that azacitidine at concentrations of 1 µM to 100 µM does not induce CYP 1A2, 2C19, or 3A4/5.

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