Finasteride (finasteride 5 mg) Dailymed

Absorption In a study of 15 healthy young subjects, the mean bioavailability of finasteride 5 mg tablets was 63% (range 34 to 108 %), based on the ratio of area under the curve (AUC) relative to an intravenous (IV) reference dose. Maximum finasteride plasma concentration averaged 37 ng/mL (range, 27 to 49 ng/mL) and was reached 1 to 2 hours postdose. Bioavailability of finasteride was not affected by food. Distribution Mean steady-state volume of distribution was 76 liters (range, 44 to 96 liters). Approximately 90% of circulating finasteride is bound to plasma proteins. There is a slow accumulation phase for finasteride after multiple dosing. After dosing with 5 mg/day of finasteride for 17 days, plasma concentrations of finasteride were 47 and 54% higher than after the first dose in men  45 to 60 years old (n=12) and ≥70 years old (n=12), respectively. Mean trough concentrations after 17 days of dosing were 6.2 ng/mL (range, 2.4 to 9.8 ng/mL) and  8.1 ng/mL (range, 1.8 to 19.7 ng/mL), respectively, in the two age groups. Although steady state was not reached in this study, mean trough plasma concentration in another study in patients with BPH (mean age, 65 years) receiving 5 mg/day was 9.4 ng/mL (range, 7.1 to 13.3 ng/mL; n=22) after over a year of dosing. Finasteride has been shown to cross the blood brain barrier but does not appear to distribute preferentially to the CSF. In 2 studies of healthy subjects (n=69) receiving finasteride tablets USP, 5 mg/day for 6 to 24 weeks, finasteride concentrations in semen ranged from undetectable (<0.1 ng/mL) to 10.54 ng/mL. In an earlier study using a less sensitive assay, finasteride concentrations in the semen of 16 subjects receiving finasteride tablets USP, 5 mg/day ranged from undetectable (<1.0 ng/mL) to 21 ng/mL. Thus, based on a 5-mL ejaculate volume, the amount of finasteride in semen was estimated to be 50- to 100-fold less than the dose of finasteride (5 mcg) that had no effect on circulating DHT levels in men (see also PRECAUTIONS, Pregnancy ). Metabolism Finasteride is extensively metabolized in the liver, primarily via the cytochrome P450 3A4 enzyme subfamily. Two metabolites, the t-butyl side chain monohydroxylated and monocarboxylic acid metabolites, have been identified that possess no more than 20% of the 5α-reductase inhibitory activity of finasteride. Excretion In healthy young subjects (n=15), mean plasma clearance of finasteride was 165 mL/min (range, 70 to 279 mL/min) and mean elimination half-life in plasma was 6 hours (range, 3 to 16 hours). Following an oral dose of 14C-finasteride in man (n=6), a mean of 39% (range, 32 to 46 %) of the dose was excreted in the urine in the form of metabolites; 57% (range, 51 to 64 %) was excreted in the feces. The mean terminal half-life of finasteride in subjects ≥70 years of age was approximately 8 hours (range, 6 to 15 hours; n=12), compared with 6 hours (range, 4 to 12 hours; n=12) in subjects 45 to 60 years of age. As a result, mean AUC(0 to 24 hr) after 17 days of dosing was 15% higher in subjects ≥70 years of age than in subjects 45 to 60 years of age (p=0.02). Special Populations Pediatric: Finasteride pharmacokinetics have not been investigated in patients <18 years of age. Gender: Finasteride pharmacokinetics in women are not available. Geriatric: No dosage adjustment is necessary in the elderly. Although the elimination rate of finasteride is decreased in the elderly, these findings are of no clinical significance. See also Pharmacokinetics, Excretion, PRECAUTIONS, Geriatric Use and DOSAGE AND ADMINISTRATION. Race: The effect of race on finasteride pharmacokinetics has not been studied. Renal Insufficiency: No dosage adjustment is necessary in patients with renal insufficiency. In patients with chronic renal impairment, with creatinine clearances ranging from 9.0 to 55 mL/min, AUC, maximum plasma concentration, half-life, and protein binding after a single dose of 14C-finasteride were similar to values obtained in healthy volunteers. Urinary excretion of metabolites was decreased in patients with renal impairment. This decrease was associated with an increase in fecal excretion of metabolites. Plasma concentrations of metabolites were significantly higher in patients with renal impairment (based on a 60% increase in total radioactivity AUC). However, finasteride has been well tolerated in BPH patients with normal renal function receiving up to 80 mg/day for 12 weeks, where exposure of these patients to metabolites would presumably be much greater. Hepatic Insufficiency: The effect of hepatic insufficiency on finasteride pharmacokinetics has not been studied. Caution should be used in the administration of  finasteride tablets USP  in those patients with liver function abnormalities, as finasteride is metabolized extensively in the liver. Drug Interactions (also see PRECAUTIONS, Drug Interactions ) No drug interactions of clinical importance have been identified. Finasteride does not appear to affect the cytochrome P450-linked drug metabolism enzyme system. Compounds that have been tested in man have included antipyrine, digoxin, propranolol, theophylline, and warfarin, and no clinically meaningful interactions were found. Mean (SD) Pharmacokinetic Parameters in Healthy Young Subjects (n=15) Mean (± SD) *Range Bioavailability 63% (34 to 108 %)* Clearance (mL/min) 165 (55) Volume of Distribution (L) 76 (14) Half-Life (hours) 6.2 (2.1) Mean (SD) Noncompartmental Pharmacokinetic Parameters After Multiple Doses of 5 mg/day in Older Men Mean (± SD) 45 to 60 yearsold (n=12) ≥70 years old (n=12) *First-dose values; all other parameters are last-dose values AUC (ng•hr/mL) 389 (98) 463 (186) Peak Concentration (ng/mL) 46.2 (8.7) 48.4 (14.7) Time to Peak (hours) 1.8 (0.7) 1.8 (0.6) Half-Life (hours)* 6.0 (1.5) 8.2 (2.5) Clinical Studies Finasteride tablets USP, 5 mg/day was initially evaluated in patients with symptoms of BPH and enlarged prostates by digital rectal examination in two 1-year, placebo-controlled, randomized, double-blind studies and their 5-year open extensions. Finasteride tablets USP was further evaluated in a long-term efficacy and safety study, a double-blind, randomized, placebo-controlled, 4-year, multicenter study. 3040 patients between the ages of 45 and 78, with moderate to severe symptoms of BPH and an enlarged prostate upon digital rectal examination, were randomized into the study (1524 to finasteride, 1516 to placebo) and 3016 patients were evaluable for efficacy. 1883 patients completed the 4-year study (1000 in the finasteride group, 883 in the placebo group). Effect on Symptom Score Symptoms were quantified using a score similar to the American Urological Association Symptom Score, which evaluated both obstructive symptoms (impairment of size and force of stream, sensation of incomplete bladder emptying, delayed or interrupted urination) and irritative symptoms (nocturia, daytime frequency, need to strain or push the flow of urine) by rating on a 0 to 5 scale for six symptoms and a 0 to 4 scale for one symptom, for a total possible score of 34. Patients in a long-term efficacy and safety study had moderate to severe symptoms at baseline (mean of approximately 15 points on a 0 to 34 point scale). Patients randomized to finasteride tablets USP who remained on therapy for 4 years had a mean (±1 SD) decrease in symptom score of 3.3 (± 5.8) points compared with 1.3 (± 5.6) points in the placebo group. (See Figure 1.) A statistically significant improvement in symptom score was evident at 1 year in patients treated with finasteride tablets USP vs. placebo (–2.3 vs –1.6), and this improvement continued through Year 4. Results seen in earlier studies were comparable to those seen in a long-term efficacy and safety study. Although an early improvement in urinary symptoms was seen in some patients, a therapeutic trial of at least 6 months was generally necessary to assess whether a beneficial response in symptom relief had been achieved. The improvement in BPH symptoms was seen during the first year and maintained throughout an additional 5 years of open extension studies. Effect on the Need for Surgery In a long-term efficacy and safety study, efficacy was also assessed by evaluating treatment failures. Treatment failure was prospectively defined as BPH-related urological events or clinical deterioration, lack of improvement and/or the need for alternative therapy. BPH-related urological events were defined as urological surgical intervention. Complete event information was available for 92% of the patients. The following table summarizes the results. Table 1 All Treatment Failures in A Long-Term Efficacy and Safety Study Patients (%) * Event Placebo N=1503 Finasteride N=1513 Relative Risk** 95% CI P Value** * Patients with multiple events may be counted more than once for each type of event ** Hazard ratio based on log rank test All Treatment Failures 37.1 26.2 0.68 (0.57 to 0.79) <0.001    Surgical Interventions for BPH 10.1 4.6 0.45 (0.32 to 0.63) <0.001    Two consecutive symptom scores≥20 9.2 6.7    Bladder Stone 0.4 0.5    Incontinence 2.1 1.7    Renal Failure 0.5 0.6    UTI 5.7 4.9    Discontinuation due to worsening of BPH, lack of improvement, or to receive other medical treatment 21.8 13.3 Compared with placebo, finasteride tablets USP was associated with a significantly lower need for BPH-related surgery. Compared with placebo, finasteride tablets USP was associated with a significantly lower risk for surgery [10.1% for placebo vs 4.6% for finasteride tablets USP; 55% reduction in risk, 95% CI: (37 to 68%)]; see Figure 2. Effect on Maximum Urinary Flow Rate In the patients in a long-term efficacy and safety study who remained on therapy for the duration of the study and had evaluable urinary flow data, finasteride tablets USP increased maximum urinary flow rate by 1.9 mL/sec compared with 0.2 mL/sec in the placebo group. There was a clear difference between treatment groups in maximum urinary flow rate in favor of finasteride tablets USP by month 4 (1.0 vs 0.3 mL/sec) which was maintained throughout the study. In the earlier 1-year studies, increase in maximum urinary flow rate was comparable to a long-term efficacy and safety study and was maintained through the first year and throughout an additional 5 years of open extension studies. Effect on Prostate Volume In a long-term efficacy and safety study, prostate volume was assessed yearly by magnetic resonance imaging (MRI) in a subset of patients. In patients treated with finasteride tablets USP who remained on therapy, prostate volume was reduced compared with both baseline and placebo throughout the 4-year study.  Finasteride tablets USP decreased prostate volume by 17.9% (from 55.9 mL at baseline to 45.8 mL at 4 years) compared with an increase of 14.1% (from 51.3 mL to 58.5 mL) in the placebo group (p<0.001). (See Figure 3.) Results seen in earlier studies were comparable to those seen in a long-term efficacy and safety study. Mean prostate volume at baseline ranged between 40 to 50 mL. The reduction in prostate volume was seen during the first year and maintained throughout an additional five years of open extension studies. Prostate Volume as a Predictor of Therapeutic Response A meta-analysis combining 1-year data from seven double-blind, placebo-controlled studies of similar design, including 4491 patients with symptomatic BPH, demonstrated that, in patients treated with finasteride tablets USP, the magnitude of symptom response and degree of improvement in maximum urinary flow rate were greater in patients with an enlarged prostate at baseline. Summary of Clinical Studies The data from these studies, showing improvement in BPH-related symptoms, reduction in treatment failure (BPH-related urological events), increased maximum urinary flow rates, and decreasing prostate volume, suggest that finasteride tablets USP arrests the disease process of BPH in men with an enlarged prostate.

Women should not handle crushed or broken finasteride tablets USP when they are pregnant or may potentially be pregnant because of the possibility of absorption of finasteride and the subsequent potential risk to the male fetus (see ; ; , and ).

Women should not handle crushed or broken finasteride tablets USP when they are pregnant or may potentially be pregnant because of the possibility of absorption of finasteride and the subsequent potential risk to the male fetus (see CONTRAINDICATIONS; WARNINGS, EXPOSURE OF WOMEN — RISK TO MALE FETUS; PRECAUTIONS, Pregnancy and HOW SUPPLIED). Physicians should inform patients that the volume of ejaculate may be decreased in some patients during treatment with finasteride tablets USP. This decrease does not appear to interfere with normal sexual function. However, impotence and decreased libido may occur in patients treated with finasteride tablets USP (see ADVERSE REACTIONS). Physicians should instruct their patients to promptly report any changes in their breasts such as lumps, pain or nipple discharge. Breast changes including breast enlargement, tenderness and neoplasm have been reported (see ADVERSE REACTIONS). Physicians should instruct their patients to read the patient package insert before starting therapy with finasteride tablets USP and to reread it each time the prescription is renewed so that they are aware of current information for patients regarding finasteride tablets USP.



See CONTRAINDICATIONS. Finasteride tablets USP are not indicated for use in women. Administration of finasteride to pregnant rats at doses ranging from 100 mcg/kg/day to 100 mg/kg/day (1 to 1000 times the recommended human dose of 5 mg/day) resulted in dose-dependent development of hypospadias in 3.6 to 100% of male offspring. Pregnant rats produced male offspring with decreased prostatic and seminal vesicular weights, delayed preputial separation and transient nipple development when given finasteride at ≥30 mcg/kg/day (≥3/10 of the recommended human dose of 5 mg/day) and decreased anogenital distance when given finasteride at ≥3 mcg/kg/day (≥3/100 of the recommended human dose of 5 mg/day). The critical period during which these effects can be induced in male rats has been defined to be days 16 to 17 of gestation. The changes described above are expected pharmacological effects of drugs belonging to the class of Type II 5α-reductase inhibitors and are similar to those reported in male infants with a genetic deficiency of Type II 5α-reductase. No abnormalities were observed in female offspring exposed to any dose of finasteride in utero. No developmental abnormalities have been observed in first filial generation (F1) male or female offspring resulting from mating finasteride-treated male rats (80 mg/kg/day; 61 times the human exposure) with untreated females. Administration of finasteride at 3 mg/kg/day (30 times the recommended human dose of 5 mg/day) during the late gestation and lactation period resulted in slightly decreased fertility in F1 male offspring. No effects were seen in female offspring. No evidence of malformations has been observed in rabbit fetuses exposed to finasteride in utero from days 6 to 18 of gestation at doses up to 100 mg/kg/day (1000 times the recommended human dose of 5 mg/day). However, effects on male genitalia would not be expected since the rabbits were not exposed during the critical period of genital system development. The in utero effects of finasteride exposure during the period of embryonic and fetal development were evaluated in the rhesus monkey (gestation days 20 to 100), a species more predictive of human development than rats or rabbits. Intravenous administration of finasteride to pregnant monkeys at doses as high as 800 ng/day (at least 60 to 120 times the highest estimated exposure of pregnant women to finasteride from semen of men taking 5 mg/day) resulted in no abnormalities in male fetuses. In confirmation of the relevance of the rhesus model for human fetal development, oral administration of a dose of finasteride (2 mg/kg/day; 20 times the recommended human dose of 5 mg/day or approximately 1 to 2 million times the highest estimated exposure to finasteride from semen of men taking 5 mg/day) to pregnant monkeys resulted in external genital abnormalities in male fetuses. No other abnormalities were observed in male fetuses and no finasteride-related abnormalities were observed in female fetuses at any dose.

Finasteride tablets USP are not indicated for use in women.