General
Prior to initiating therapy with finasteride, appropriate
evaluation should be performed to identify other conditions such as infection,
prostate cancer, stricture disease, hypotonic bladder or other neurogenic
disorders that might mimic BPH.
Patients with large residual urinary volume and/or severely diminished
urinary flow should be carefully monitored for obstructive uropathy. These
patients may not be candidates for finasteride therapy.
Caution should be used in the administration of finasteride in those patients
with liver function abnormalities, as finasteride is metabolized extensively in
the liver.
Effects on PSA and Prostate Cancer Detection
No clinical benefit has been demonstrated in patients with
prostate cancer treated with finasteride. Patients with BPH and elevated PSA
were monitored in controlled clinical studies with serial PSAs and prostate
biopsies. In these BPH studies, finasteride did not appear to alter the rate of
prostate cancer detection, and the overall incidence of prostate cancer was not
significantly different in patients treated with finasteride or placebo.
Finasteride causes a decrease in serum PSA levels by approximately 50% in
patients with BPH, even in the presence of prostate cancer. This decrease is
predictable over the entire range of PSA values, although it may vary in
individual patients. Analysis of PSA data from over 3000 patients in a long-term
efficacy and safety study confirmed that in typical patients treated with
finasteride for six months or more, PSA values should be doubled for comparison
with normal ranges in untreated men. This adjustment preserves the sensitivity
and specificity of the PSA assay and maintains its ability to detect prostate
cancer.
Any sustained increases in PSA levels while on finasteride should be
carefully evaluated, including consideration of non-compliance to therapy with
finasteride.
Percent free PSA (free to total PSA ratio) is not significantly decreased by
finasteride. The ratio of free to total PSA remains constant even under the
influence of finasteride. If clinicians elect to use percent free PSA as an aid
in the detection of prostate cancer in men undergoing finasteride therapy, no
adjustment to its value appears necessary.
Information for Patients
Women should not handle crushed or broken finasteride tablets
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. This decrease does
not appear to interfere with normal sexual function. However, impotence and
decreased libido may occur in patients treated with finasteride (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 and to reread it each time the
prescription is renewed so that they are aware of current information for
patients regarding finasteride.
Drug/Laboratory Test Interactions
In patients with BPH, finasteride has no effect on circulating
levels of cortisol, estradiol, prolactin, thyroid-stimulating hormone, or
thyroxine. No clinically meaningful effect was observed on the plasma lipid
profile (i.e., total cholesterol, low density lipoproteins, high density
lipoproteins and triglycerides) or bone mineral density. Increases of about 10%
were observed in luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
in patients receiving finasteride, but levels remained within the normal range.
In healthy volunteers, treatment with finasteride did not alter the response of
LH and FSH to gonadotropin-releasing hormone indicating that the
hypothalamic-pituitary-testicular axis was not affected.
Treatment with finasteride for 24 weeks to evaluate semen parameters in
healthy male volunteers revealed no clinically meaningful effects on sperm
concentration, mobility, morphology, or pH. A 0.6 mL (22.1%) median decrease in
ejaculate volume with a concomitant reduction in total sperm per ejaculate was
observed. These parameters remained within the normal range and were reversible
upon discontinuation of therapy with an average time to return to baseline of 84
weeks.
Drug Interactions
No drug interactions of clinical importance have been identified.
Finasteride does not appear to affect the cytochrome P450-linked drug
metabolizing enzyme system. Compounds that have been tested in man have included
antipyrine, digoxin, propranolol, theophylline, and warfarin and no clinically
meaningful interactions were found.
Other Concomitant Therapy: Although specific
interaction studies were not performed, finasteride was concomitantly used in
clinical studies with acetaminophen, acetylsalicylic acid,
angiotensin-converting enzyme (ACE) inhibitors, analgesics, anti-convulsants,
beta-adrenergic blocking agents, diuretics, calcium channel blockers, cardiac
nitrates, HMG-CoA reductase inhibitors, nonsteroidal anti-inflammatory drugs
(NSAIDs), benzodiazepines, H2 antagonists and quinolone
anti-infectives without evidence of clinically significant adverse
interactions.
Carcinogenesis, Mutagenesis, Impairment of
Fertility
No evidence of a tumorigenic effect was observed in a 24-month
study in Sprague-Dawley rats receiving doses of finasteride up to 160 mg/kg/day
in males and 320 mg/kg/day in females. These doses produced respective systemic
exposure in rats of 111 and 274 times those observed in man receiving the
recommended human dose of 5 mg/day. All exposure calculations were based on
calculated AUC(0-24 hr) for animals and mean AUC(0-24 hr) for man (0.4 µg•hr/mL).
In a 19-month carcinogenicity study in CD-1 mice, a statistically significant
(p≤0.05) increase in the incidence of testicular Leydig cell adenomas was
observed at a dose of 250 mg/kg/day (228 times the human exposure). In mice at a
dose of 25 mg/kg/day (23 times the human exposure, estimated) and in rats at a
dose of ≥40 mg/kg/day (39 times the human exposure) an increase in the incidence
of Leydig cell hyperplasia was observed. A positive correlation between the
proliferative changes in the Leydig cells and an increase in serum LH levels (2-
to 3-fold above control) has been demonstrated in both rodent species treated
with high doses of finasteride. No drug-related Leydig cell changes were seen in
either rats or dogs treated with finasteride for 1 year at doses of 20 mg/kg/day
and 45 mg/kg/day (30 and 350 times, respectively, the human exposure) or in mice
treated for 19 months at a dose of 2.5 mg/kg/day (2.3 times the human exposure,
estimated).
No evidence of mutagenicity was observed in an in vitro
bacterial mutagenesis assay, a mammalian cell mutagenesis assay, or in an
in vitro alkaline elution assay. In an in vitro chromosome aberration assay, using Chinese hamster
ovary cells, there was a slight increase in chromosome aberrations. These
concentrations correspond to 4000-5000 times the peak plasma levels in man given
a total dose of 5 mg. In an in vivo chromosome
aberration assay in mice, no treatment-related increase in chromosome aberration
was observed with finasteride at the maximum tolerated dose of 250 mg/kg/day
(228 times the human exposure) as determined in the carcinogenicity studies.
In sexually mature male rabbits treated with finasteride at 80 mg/kg/day (543
times the human exposure) for up to 12 weeks, no effect on fertility, sperm
count, or ejaculate volume was seen. In sexually mature male rats treated with
80 mg/kg/day of finasteride (61 times the human exposure), there were no
significant effects on fertility after 6 or 12 weeks of treatment; however, when
treatment was continued for up to 24 or 30 weeks, there was an apparent decrease
in fertility, fecundity and an associated significant decrease in the weights of
the seminal vesicles and prostate. All these effects were reversible within 6
weeks of discontinuation of treatment. No drug-related effect on testes or on
mating performance has been seen in rats or rabbits. This decrease in fertility
in finasteride-treated rats is secondary to its effect on accessory sex organs
(prostate and seminal vesicles) resulting in failure to form a seminal plug. The
seminal plug is essential for normal fertility in rats and is not relevant in
man.
Pregnancy
Pregnancy Category X
See CONTRAINDICATIONS.
Finasteride is not indicated for use in women.
Administration of finasteride to pregnant rats at doses ranging from 100
µg/kg/day to 100 mg/kg/day (1-1000 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 µg/kg/day (≥3/10 of the recommended
human dose of 5 mg/day) and decreased anogenital distance when given finasteride
at ≥3 µg/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 16-17 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 6-18 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 20-100), 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 1-2 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.
Nursing Mothers
Finasteride is not indicated for use in women.
It is not known whether finasteride is excreted in human milk.
Pediatric Use
Finasteride is not indicated for use in pediatric patients.
Safety and effectiveness in pediatric patients have not been
established.
Geriatric Use
Of the total number of subjects included in a long-term efficacy
and safety study, 1480 and 105 subjects were 65 and over and 75 and over,
respectively. No overall differences in safety or effectiveness were observed
between these subjects and younger subjects, and other reported clinical
experience has not identified differences in responses between the elderly and
younger patients. No dosage adjustment is necessary in the elderly (see CLINICAL PHARMACOLOGY,
Pharmacokinetics and Clinical
Studies).