Drospirenone and estradiol

Inducers and inhibitors of CYP3A4 may affect estrogen drug metabolism and decrease or increase the estrogen plasma concentration. ( 7.1 ) Serum potassium concentration may increase in women taking drospirenone with other drugs that have the potential to increase potassium. ( 7.1 )

7.1 Metabolic Interactions Effect of Drospirenone on Other Drugs The potential effect of DRSP on CYP2C19 activity was investigated in a clinical pharmacokinetic study using omeprazole as a marker substrate. No significant effect of DRSP on the systemic clearance of the CYP3A4 product omeprazole sulfone was found. These results demonstrated that DRSP did not inhibit CYP2C19 and CYP3A4 in vivo . Two further clinical drug-drug interaction studies using simvastatin and midazolam as marker substrates for CYP3A4, respectively, were performed and the results of these studies demonstrated that pharmacokinetics of the CYP3A4 substrates were not influenced by steady-state DRSP concentrations.

Co-administration of DRSP and drugs that may increase serum potassium: There is a potential for an increase in serum potassium in women taking DRSP with other drugs that may affect electrolytes, such as ACE inhibitors, angiotensin receptor blockers, or NSAIDs, more pronounced in diabetic women [see Warnings and Precautions (5.2) , and Clinical Pharmacology (12.3) ] . Electrolytes were studied in postmenopausal women with hypertension and/or diabetes mellitus requiring an ACE inhibitor or angiotensin receptor blocker. After 28 days of exposure to 1 mg E2 and 3 mg DRSP (n=112) or placebo (n=118).

The mean change from baseline in serum potassium was 0.11 mEq/L for the E2/DRSP group and 0.08 mEq/L for the placebo group. None of the subjects with serum potassium concentrations ≥5.5 mEq/L had cardiovascular adverse events. A drug-drug interaction study of DRSP 3 mg/E2 1 mg versus placebo was performed in mildly hypertensive postmenopausal women taking enalapril maleate 10 mg twice daily. Potassium concentrations were obtained every other day for a total of 2 weeks in all subjects. Mean serum potassium concentrations in the DRSP/E2 treatment group relative to baseline were 0.22 mEq/L higher than those in the placebo group.

On Day 14, the ratios for serum potassium C max and AUC in the DRSP/E2 group to those in the placebo group were 0.955 (90% CI: 0.914, 0.999) and 1.01 (90% CI: 0.944, 1.08), respectively. No woman in either treatment group developed hyperkalemia (serum potassium concentrations >5.5 mEq/L). Of note, occasional or chronic use of NSAID medication was not restricted in any of the Angeliq clinical trials. Effect of Other Drugs on Estrogens and Progestins In vitro and in vivo studies have shown that estrogens and progestins are metabolized partially by cytochrome P450 3A4 (CYP3A4). Therefore, inducers or inhibitors of CYP3A4 may affect estrogen drug metabolism.

In a clinical drug-drug interaction study conducted in premenopausal women, once daily co-administration of DRSP 3 mg/E2 1.5 mg containing tablets with strong CYP3A4 inhibitor, ketoconazole 200 mg twice daily for 10 days resulted in a moderate increase of exposure and a mild increase of peak concentration for DRSP. The E2 exposure and peak concentration were unaffected by ketoconazole, although the exposure and peak concentration of estrone (E1) increased. Although no clinically relevant effects on any safety or laboratory parameters including serum potassium were observed, this study only assessed women for 10 days.

The clinical impact for a woman taking a DRSP-containing combination hormone and chronic use of a CYP3A4/5 inhibitor is unknown. Substances decreasing the exposure and possibly diminishing the efficacy of estrogens and progestins (enzyme inducers) Inducers of CYP3A4 such as St. John's wort ( Hypericum perforatum ), phenobarbital, carbamazepine, and rifampin may reduce plasma concentrations of estrogens and progestins, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile.

Substances increasing the exposure of estrogens and progestins (enzyme inhibitors) Concomitant administration of moderate or strong CYP3A4 inhibitors such as azole antifungals (for example, ketoconazole, itraconazole, voriconazole, fluconazole), verapamil, macrolides (for example, clarithromycin, erythromycin), diltiazem, and grapefruit juice did increase the plasma concentrations of the estrogen or the progestin or both [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3) ].

HIV/HCV protease inhibitors and non-nucleoside reverse transcriptase inhibitors Significant changes (increase or decrease) in the plasma concentrations of estrogen and progestin have been noted in some cases of co-administration with HIV/HCV protease inhibitors or with non-nucleoside reverse transcriptase inhibitors.

7.2 Interaction with Alcohol Acute alcohol ingestion during use of hormone therapy may lead to elevations of circulating E2 concentrations.

8.1 Pregnancy Risk Summary Angeliq is not indicated for use in pregnancy . There are no data with the use of Angeliq in pregnant women, however, epidemiologic studies and meta-analyses have not found an increased risk of genital or nongenital birth defects (including cardiac anomalies or limb-reduction defects) following exposure to combined hormonal contraceptives (estrogens and progestins) before conception or during early pregnancy. In reproduction studies in rats, rabbits and monkeys with oral administration of DRSP either as single compound or in combination with EE, no non-genital teratogenicity was observed.

Adverse developmental outcomes like an increase in fetal mortality and a retardation of fetal maturation were seen in rats and rabbits at exposures to DRSP exceeding the human exposure by a factor of >15 (in rats) or >60 (rabbits). Related to the antiandrogenic activity of drospirenone, a feminization of male fetuses and an impairment of male fertility was observed in rats (>150 times the human exposure to drospirenone) but not in monkeys (at up to more than 300 times the human exposure to drospirenone). Due to the large safety margins observed in the animal studies only a low likelihood of an increased risk for human pregnancy was concluded ( see Data ). 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 In an embryo-fetal toxicity study in pregnant rats, DRSP was given from day 6 to 15 of gestation orally at doses of 5, 15 and 45 mg/kg/day, more than 60 times the human exposure starting from the low dose based on AUC of DRSP. A slight increase in postimplantational loss and a slight increase in retardation of fetal development (e.g. delayed ossification of bones of the feet) was seen in the two higher doses. No teratogenicity was observed in rats.

In an embryo-fetal study in rabbits, DRSP was given from day 6 to 18 of gestation orally at doses of 10, 30 and 100 mg/kg/day, about 20, 60 and 250 times the human exposure based on AUC. This resulted in a retardation of fetal development (delayed ossification of small bones, multiple fusions of ribs) at the high dose only and in an increase in fetal loss from the mid dose level. No compound-related teratogenicity was seen in rabbits. In a further embryo-fetal toxicity study in pregnant rats, DRSP was orally administered in combination with ethinyl estradiol (100:1) from day 6 to 17 of gestation at doses of 1, 3 and 10 mg/kg/day DRSP, at about 1, 3 and…