Eplerenone (Page 3 of 5)

8.2 Lactation

Risk Summary

There are no human data available on whether eplerenone is present in human milk, or has effects on breastfed infants or on milk production. Eplerenone was present in the milk of lactating rats. When a drug is present in animal milk, it is likely that the drug will be present in human milk.

8.3 Females and Males of Reproductive Potential

Infertility

Based on animal data, use of eplerenone may compromise male fertility. In mature rats, male fertility was decreased with eplerenone exposure at 17 times the 100 mg/day human therapeutic dose. Reversibility of effects was not evaluated [see Nonclinical Toxicology (13.1)].

8.4 Pediatric Use

In a 10-week study of 304 hypertensive pediatric patients age 4 to 16 years treated with eplerenone up to 100 mg per day, doses that produced exposure similar to that in adults, eplerenone did not lower blood pressure effectively. In this study and in a 1-year pediatric safety study in 149 patients (age range 5 to 17 years), the incidence of reported adverse events was similar to that of adults.

Eplerenone has not been studied in hypertensive patients less than 4 years old because the study in older pediatric patients did not demonstrate effectiveness.

Eplerenone has not been studied in pediatric patients with heart failure.

8.5 Geriatric Use

Heart Failure Post-Myocardial Infarction

Of the total number of patients in EPHESUS, 3340 (50%) were 65 and over, while 1326 (20%) were 75 and over. Patients greater than 75 years did not appear to benefit from the use of eplerenone [see Clinical Studies (14.1)].

No differences in overall incidence of adverse events were observed between elderly and younger patients. However, due to age-related decreases in creatinine clearance, the incidence of laboratory-documented hyperkalemia was increased in patients 65 and older [see Warnings and Precautions (5.1)].

Hypertension

Of the total number of subjects in clinical hypertension studies of eplerenone, 1123 (23%) were 65 and over, while 212 (4%) were 75 and over. No overall differences in safety or effectiveness were observed between elderly subjects and younger subjects, however due to age-related decreases in creatine clearance, the risk of hyperkalemia may be increased [see Warnings and Precautions (5.1)].

10 OVERDOSAGE

No cases of human overdosage with eplerenone have been reported. Lethality was not observed in mice, rats, or dogs after single oral doses that provided Cmax exposures at least 25 times higher than in humans receiving eplerenone 100 mg/day. Dogs showed emesis, salivation, and tremors at a Cmax 41 times the human therapeutic Cmax , progressing to sedation and convulsions at higher exposures.

The most likely manifestation of human overdosage would be anticipated to be hypotension or hyperkalemia. Eplerenone cannot be removed by hemodialysis. Eplerenone has been shown to bind extensively to charcoal. If symptomatic hypotension should occur, supportive treatment should be instituted. If hyperkalemia develops, standard treatment should be initiated.

11 DESCRIPTION

Eplerenone tablets contain eplerenone, a blocker of aldosterone binding at the mineralocorticoid receptor.

Eplerenone is chemically described as Pregn-4-ene-7,21-dicarboxylic acid, 9,11-epoxy-17-hydroxy-3-oxo-, γ-lactone, methyl ester, (7α,11α,17α)-. Its empirical formula is C24 H30 O6 and it has a molecular weight of 414.50. The structural formula of eplerenone is represented below:

Chemical Structure

Eplerenone is an odorless, white to off-white crystalline powder. It is very slightly soluble in water, with its solubility essentially pH-independent. The octanol/water partition coefficient of eplerenone is approximately 7.1 at pH 7.0.

Eplerenone tablets for oral administration contain 25 mg or 50 mg of eplerenone and the following inactive ingredients: lactose, microcrystalline cellulose, croscarmellose sodium, hypromellose, sodium lauryl sulfate, talc, magnesium stearate, titanium dioxide, polyethylene glycol, polysorbate 80, and iron oxide yellow and iron oxide red.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Eplerenone binds to the mineralocorticoid receptor and blocks the binding of aldosterone, a component of the renin-angiotensin-aldosterone-system (RAAS). Aldosterone synthesis, which occurs primarily in the adrenal gland, is modulated by multiple factors, including angiotensin II and non-RAAS mediators such as adrenocorticotropic hormone (ACTH) and potassium. Aldosterone binds to mineralocorticoid receptors in both epithelial (e.g., kidney) and nonepithelial (e.g., heart, blood vessels, and brain) tissues and increases blood pressure through induction of sodium reabsorption and possibly other mechanisms.

Eplerenone has been shown to produce sustained increases in plasma renin and serum aldosterone, consistent with inhibition of the negative regulatory feedback of aldosterone on renin secretion. The resulting increased plasma renin activity and aldosterone circulating levels do not overcome the effects of eplerenone.

Eplerenone selectively binds to human mineralocorticoid receptors relative to its binding to recombinant human glucocorticoid, progesterone, and androgen receptors.

12.2 Pharmacodynamics

There was no significant change in average heart rate among patients treated with eplerenone in the combined clinical studies. No consistent effects of eplerenone on heart rate, QRS duration, or PR or QT interval were observed in 147 normal subjects evaluated for electrocardiographic changes during pharmacokinetic studies.

12.3 Pharmacokinetics

Eplerenone is cleared predominantly by cytochrome P450 (CYP) 3A4 metabolism, with an elimination half-life of 3 to 6 hours. Steady state is reached within 2 days. Absorption is not affected by food. Inhibitors of CYP3A (e.g., ketoconazole, saquinavir) increase blood levels of eplerenone.

Absorption and Distribution

Mean peak plasma concentrations of eplerenone are reached approximately 1.5 to 2 hours following oral administration. Absorption is not affected by food. The absolute bioavailability of eplerenone is 69% following administration of a 100 mg oral tablet. Both peak plasma levels (Cmax ) and area under the curve (AUC) are dose proportional for doses of 25 mg to 100 mg and less than proportional at doses above 100 mg. Upon repeat dosing, steady state levels are reached within 2 days.

The plasma protein binding of eplerenone is about 50% and it is primarily bound to alpha 1-acid glycoproteins. The apparent volume of distribution at steady state ranged from 42 to 90 L. Eplerenone does not preferentially bind to red blood cells.

Metabolism and Excretion

Eplerenone metabolism is primarily mediated via CYP3A4. No active metabolites of eplerenone have been identified in human plasma.

Less than 5% of an eplerenone dose is recovered as unchanged drug in the urine and feces. Following a single oral dose of radiolabeled drug, approximately 32% of the dose was excreted in the feces and approximately 67% was excreted in the urine. The elimination half-life of eplerenone is approximately 3 to 6 hours. The apparent plasma clearance is approximately 10 L/hr.

Age, Gender, and Race

The pharmacokinetics of eplerenone at a dose of 100 mg once daily has been investigated in the elderly (≥65 years), in males and females, and in Blacks. At steady state, elderly subjects had increases in Cmax (22%) and AUC (45%) compared with younger subjects (18 to 45 years). The pharmacokinetics of eplerenone did not differ significantly between males and females. At steady state, Cmax was 19% lower and AUC was 26% lower in Blacks [see Dosage and Administration (2.4) and Use in Specific Populations (8.5)].

Renal Impairment

The pharmacokinetics of eplerenone was evaluated in patients with varying degrees of renal impairment and in patients undergoing hemodialysis. Compared with control subjects, steady state AUC and Cmax were increased by 38% and 24%, respectively, in patients with severe renal impairment and were decreased by 26% and 3%, respectively, in patients undergoing hemodialysis. No correlation was observed between plasma clearance of eplerenone and creatinine clearance. Eplerenone is not removed by hemodialysis [see Warnings and Precautions (5.1)].

Hepatic Impairment

The pharmacokinetics of eplerenone 400 mg has been investigated in patients with moderate (Child-Pugh Class B) hepatic impairment and compared with normal subjects. Steady state Cmax and AUC of eplerenone were increased by 3.6% and 42%, respectively.

Heart Failure

The pharmacokinetics of eplerenone 50 mg was evaluated in 8 patients with heart failure (NYHA classification II–IV) and 8 matched (gender, age, weight) healthy controls. Compared with the controls, steady state AUC and Cmax in patients with stable heart failure were 38% and 30% higher, respectively.

Drug-Drug Interactions

Eplerenone is metabolized primarily by CYP3A4. Inhibitors of CYP3A cause increased exposure [see Drug Interactions (7.1)].

Drug-drug interaction studies were conducted with a 100 mg dose of eplerenone.

Following a single dose of eplerenone 100 mg and CYP3A inhibitor ketoconazole 200 mg twice a day, eplerenone’s Cmax was 1.7-fold and AUC was 5.4-fold compared with eplerenone alone.

Administration of eplerenone with moderate CYP3A inhibitors (e.g., erythromycin 500 mg BID, verapamil 240 mg once daily, saquinavir 1200 mg three times a day, fluconazole 200 mg once daily) resulted in increases in Cmax of eplerenone ranging from 40% to 60% and AUC from 100% to 190%.

Grapefruit juice caused a 25% increase in exposure.

Eplerenone is not an inhibitor of CYP1A2, CYP3A4, CYP2C19, CYP2C9, or CYP2D6. Eplerenone did not inhibit the metabolism of amiodarone, amlodipine, astemizole, chlorzoxazone, cisapride, dexamethasone, dextromethorphan, diclofenac, 17α-ethinyl estradiol, fluoxetine, losartan, lovastatin, mephobarbital, methylphenidate, methylprednisolone, metoprolol, midazolam, nifedipine, phenacetin, phenytoin, simvastatin, tolbutamide, triazolam, verapamil, or warfarin in vitro. Eplerenone is not a substrate or an inhibitor of P-Glycoprotein at clinically relevant doses.

No clinically significant drug-drug pharmacokinetic interactions were observed when eplerenone was administered with cisapride, cyclosporine, digoxin, glyburide, midazolam, oral contraceptives (norethindrone/ethinyl estradiol), simvastatin, or warfarin. St. John’s wort (a CYP3A inducer) caused a small (about 30%) decrease in eplerenone AUC.

No significant changes in eplerenone pharmacokinetics were observed when eplerenone was administered with aluminum- and magnesium-containing antacids.

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