General

AROMASIN Tablets should not be administered to premenopausal women. AROMASIN should not be coadministered with estrogen-containing agents as these could interfere with its pharmacologic action.

Hepatic Insufficiency

The pharmacokinetics of exemestane have been investigated in subjects with moderate or severe hepatic insufficiency (Childs-Pugh B or C). Following a single 25-mg oral dose, the AUC of exemestane was approximately 3 times higher than that observed in healthy volunteers. The safety of chronic dosing in patients with moderate or severe hepatic impairment has not been studied. Based on experience with exemestane at repeated doses up to 200 mg daily that demonstrated a moderate increase in non-life threatening adverse events, dosage adjustment does not appear to be necessary.

Renal Insufficiency

The AUC of exemestane after a single 25-mg dose was approximately 3 times higher in subjects with moderate or severe renal insufficiency (creatinine clearance less than 35 mL/min/1.73 m2) compared with the AUC in healthy volunteers. The safety of chronic dosing in patients with moderate or severe renal impairment has not been studied. Based on experience with exemestane at repeated doses up to 200 mg daily that demonstrated a moderate increase in non-life threatening adverse events, dosage adjustment does not appear to be necessary.

Laboratory Tests

In patients with early breast cancer the incidence of hematological abnormalities of Common Toxicity Criteria (CTC) grade greater than or equal to 1 was lower in the exemestane treatment group, compared with tamoxifen. Incidence of CTC grade 3 or 4 abnormalities was low (approximately 0.1%) in both treatment groups. Approximately 20% of patients receiving exemestane in clinical studies in advanced breast cancer, experienced CTC grade 3 or 4 lymphocytopenia. Of these patients, 89% had a pre-existing lower grade lymphopenia. Forty percent of patients either recovered or improved to a lesser severity while on treatment. Patients did not have a significant increase in viral infections, and no opportunistic infections were observed. Elevations of serum levels of AST, ALT, alkaline phosphatase and gamma glutamyl transferase less than greater than 5 times the upper value of the normal range (i.e., greater than or equal to CTC grade 3) have been rarely reported in patients treated for advanced breast cancer but appear mostly attributable to the underlying presence of liver and/or bone metastases. In the comparative study in advanced breast cancer patients, CTC grade 3 or 4 elevation of gamma glutamyl transferase without documented evidence of liver metastasis was reported in 2.7% of patients treated with AROMASIN and in 1.8% of patients treated with megestrol acetate.

In patients with early breast cancer, elevations in bilirubin, alkaline phosphatase, and creatinine were more common in those receiving exemestane than either tamoxifen or placebo. Treatment emergent bilirubin elevations (any CTC grade) occurred in 5.3% of exemestane patients and 0.8% of tamoxifen patients on the IES, and in 6.9% of exemestane treated patients vs. 0% of placebo treated patients on the 027 study. CTC grade 3–4 increases in bilirubin occurred in 0.9% of exemestane treated patients compared to 0.1% of tamoxifen treated patients. Alkaline phosphatase elevations of any CTC grade occurred in 15.0% of exemestane treated patients on the IES compared to 2.6% of tamoxifen treated patients, and in 13.7% of exemestane treated patients compared to 6.9% of placebo treated patients on study 027. Creatinine elevations occurred in 5.8% of exemestane treated patients and 4.3% of tamoxifen treated patients on the IES and in 5.5% of exemestane treated patients and 0% of placebo treated patients on study 027.

Reductions in bone mineral density (BMD) over time are seen with exemestane use. Table 7 describes changes in BMD from baseline to 24 months in patients receiving exemestane compared to patients receiving tamoxifen (IES) or placebo (027). Concomitant use of bisphosphonates, Vitamin D supplementation and Calcium was not allowed.

  
  
Drug Interactions

Exemestane is extensively metabolized by CYP 3A4, but coadministration of ketoconazole, a potent inhibitor of CYP 3A4, has no significant effect on exemestane pharmacokinetics. Significant pharmacokinetic interactions mediated by inhibition of CYP isoenzymes therefore appear unlikely. Co-medications that induce CYP 3A4 (e.g., rifampicin, phenytoin, carbamazepine, phenobarbital, or St. John's wort) may significantly decrease exposure to exemestane. Dose modification is recommended for patients who are also receiving a potent CYP 3A4 inducer (see DOSAGE AND ADMINISTRATION and CLINICAL PHARMACOLOGY).

Drug/Laboratory Tests Interactions

No clinically relevant changes in the results of clinical laboratory tests have been observed.

Carcinogenesis, Mutagenesis, Impairment of Fertility

A 2-year carcinogenicity study in mice at doses of 50, 150 and 450 mg/kg/day exemestane (gavage), resulted in an increased incidence of hepatocellular adenomas and/or carcinomas in both genders at the high dose level. Plasma AUCs(0–24hr) at the high dose were 2575 ± 386 and 5667 ± 1833 ng.hr/mL in males and females (approx. 34 and 75 fold the AUC in postmenopausal patients at the recommended clinical dose). An increased incidence of renal tubular adenomas was observed in male mice at the high dose of 450 mg/kg/day. Since the doses tested in mice did not achieve an MTD, neoplastic findings in organs other than liver and kidneys remain unknown. 

A separate carcinogenicity study was conducted in rats at the doses of 30, 100 and 315 mg/kg/day exemestane (gavage) for 92 weeks in males and 2 years in females. No evidence of carcinogenic activity up to the highest dose tested of 315 mg/kg/day was observed in females. The male rat study was inconclusive since it was terminated prematurely at Week 92. At the highest dose, plasma AUC(0–24hr) levels in male (1418 ± 287 ng.hr/mL) and female (2318 ± 1067 ng.hr/mL) rats were 19 and 31 fold higher than those measured in postmenopausal cancer patients, receiving the recommended clinical dose.

Exemestane was not mutagenic in vitro in bacteria (Ames test) or mammalian cells (V79 Chinese hamster lung cells). Exemestane was clastogenic in human lymphocytes in vitro without metabolic activation but was not clastogenic in vivo (micronucleus assay in mouse bone marrow). Exemestane did not increase unscheduled DNA synthesis in rat hepatocytes when tested in vitro.

In a pilot reproductive study in rats, male rats were treated with doses of 125–1000 mg/kg/day exemestane, beginning 63 days prior to and during cohabitation. Untreated female rats showed reduced fertility when mated to males treated with greater than or equal to 500 mg/kg/day exemestane (greater than or equal to 200 times the recommended human dose on a mg/m2 basis). In a separate study, exemestane was given to female rats at 4–100 mg/kg/day beginning 14 days prior to mating and through day 15 or 20 of gestation. Exemestane increased the placental weights at greater than or equal to 4 mg/kg/day greater than or equal to 1.5 times the human dose on a mg/m2 basis). Exemestane showed no effects on ovarian function, mating behavior, and conception rate in rats given doses up to 20 mg/kg/day (approximately 8 times the recommended human dose on a mg/m2 basis), however, decreases in mean litter size and fetal body weight, along with delayed ossification were evidenced at greater than or equal to 20 mg/kg/day. In general toxicology studies, changes in the ovary, including hyperplasia, an increase in the incidence of ovarian cysts and a decrease in corpora lutea were observed with variable frequency in mice, rats and dogs at doses that ranged from 3–20 times the human dose on a mg/m2 basis. 

PregnancyPregnancy Category D

See WARNINGS.

Nursing Mothers

AROMASIN is only indicated in postmenopausal women. However, radioactivity related to exemestane appeared in rat milk within 15 minutes of oral administration of radiolabeled exemestane. Concentrations of exemestane and its metabolites were approximately equivalent in the milk and plasma of rats for 24 hours after a single oral dose of 1 mg/kg 14C-exemestane. It is not known whether exemestane is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised if a nursing woman is inadvertently exposed to AROMASIN (see WARNINGS).

Pediatric Use

The safety and effectiveness of AROMASIN in pediatric patients have not been evaluated.

Geriatric Use

The use of AROMASIN in geriatric patients does not require special precautions.