SIDE EFFECTS
Clinical Studies for finasteride 1 mg in the Treatment
of Male Pattern Hair Loss
In controlled clinical trials for finasteride of 12-month
duration, 1.4% of the patients were discontinued due to
adverse experiences that were considered to be possibly,
probably or definitely drug-related (1.6% for placebo);
1.2% of patients on finasteride and 0.9% of patients on
placebo discontinued therapy because of a drug-related
sexual adverse experience. The following clinical adverse
reactions were reported as possibly, probably or definitely
drug-related in ³1% of patients treated for 12 months
with finasteride or placebo, respectively: decreased libido
(1.8%, 1.3%), erectile dysfunction (1.3%, 0.7%) and ejaculation
disorder (1.2%, 0.7%; primarily decreased volume of ejaculate:[0.8%,
0.4%]). Integrated analysis of clinical adverse experiences
showed that during treatment with finasteride, 36 (3.8%)
of 945 men had reported one or more of these adverse experiences
as compared to 20 (2.1%) of 934 men treated with placebo
(p=0.04). Resolution occurred in all men who discontinued
therapy with finasteride due to these side effects and
in 58% of those who continued therapy.
In a study of finasteride 1 mg daily in healthy men,
a median decrease in ejaculate volume of 0.3 mL (-11%)
compared with 0.2 mL (–8%) for placebo was observed
after 48 weeks of treatment. Two other studies showed
that finasteride at 5 times the dosage of finasteride
(5 mg daily) produced significant median decreases of
approximately 0.5 mL (-25%) compared to placebo in ejaculate
volume but this was reversible after discontinuation of
treatment.
In the clinical studies with finasteride, the incidences
for breast tenderness and enlargement, and for hypersensitivity
reactions in finasteride-treated patients were not different
from those in patients treated with placebo.
Controlled Clinical Trials and Long-Term Open Extension
Studies for PROSCAR* (finasteride 5 mg) in the Treatment
of Benign Prostatic Hyperplasia
In controlled clinical trials for PROSCAR of 12-month
duration, 1.3% of the patients were discontinued due to
adverse experiences that were considered to be possibly,
probably or definitely drug-related (0.9% for placebo);
only one patient on PROSCAR (0.2%) and one patient on
placebo (0.2%) discontinued therapy because of a drug-related
sexual adverse experience. The following clinical adverse
reactions were reported as possibly, probably or definitely
drug-related in ³1% of patients treated for 12 months
with PROSCAR or placebo, respectively: erectile dysfunction
(3.7%, 1.1%), decreased libido (3.3%, 1.6%) and decreased
volume of ejaculate (2.8%, 0.9%). The adverse experience
profiles for patients treated with finasteride 1 mg/day
for 12 months and those maintained on PROSCAR for 24 to
48 months were similar to that observed in the 12-month
controlled studies with PROSCAR. Sexual adverse experiences
resolved with continued treatment in over 60% of patients
who reported them.
Adverse Effects Reported in Post-Marketing Experience
for PROSCAR (finasteride 5 mg)
Breast tenderness and enlargement, as well as hypersensitivity
reactions, including lip swelling and skin rash have been
reported.
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 include antipyrine,
digoxin, propranolol, theophylline, and warfarin and no
interactions were found.
Other concomitant therapy: Although specific interaction
studies were not performed, finasteride doses of 1 mg
or more were concomitantly used in clinical studies with
acetaminophen, a-blockers, analgesics, angiotensin-converting
enzyme (ACE) inhibitors, anticonvulsants, benzodiazepines,
beta blockers, calcium-channel blockers, cardiac nitrates,
diuretics, H2 antagonists, HMG-CoA reductase inhibitors,
prostaglandin synthetase inhibitors (NSAIDs), and quinolone
anti-infectives without evidence of clinically significant
adverse interactions.
Drug/Laboratory Test Interactions
In clinical studies with finasteride in men 18-41 years
of age, the mean value of serum prostate-specific antigen
(PSA) decreased from 0.7 ng/mL at baseline to 0.5 ng/mL
at Month 12. When finasteride is used in older men who have
benign prostatic hyperplasia (BPH), PSA levels are decreased
by approximately 50%. Until further information is gathered
in men >41 years of age without BPH, consideration should
be given to doubling the PSA level in men undergoing this
test while taking finasteride.
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