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PROSCAR* (finasteride, MSD), a synthetic 4?azasteroid compound,
is a specific inhibitor of Type II 5a?reductase , an intracellular
enzyme which metabolizes testosterone into the more potent
androgen dihydrotestosterone (DHT). In benign prostatic hyperplasia
(BPH), enlargement of the prostate gland is dependent upon
the conversion of testosterone to DHT within the prostate.
PROSCAR is highly effective in reducing circulating and intraprostatic
DHT. Finasteride has no affinity for the androgen receptor.
In the PROSCAR Long-Term Efficacy and Safety Study (PLESS),
the effect of therapy with PROSCAR on BPH-related urologic
events (surgical intervention [e.g., transurethal resection
of the prostate and prostatectomy] or acute urinary retention
requiring catheterization) was assessed over a 4-year period
in 3016 patients with moderate to severe symptoms of BPH.
In this double-blind, randomized, placebo-controlled multicenter
study, treatment with PROSCAR reduced the risk of total urologic
events by 51% and was also associated with a marked and sustained
regression in prostate volume, and a sustained increase in
maximum urinary flow rate and improvement in symptoms.
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DOSAGE
AND ADMINISTRATION |
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The recommended dosage is one 5?mg tablet daily with or without
food.
DOSAGE IN RENAL INSUFFICIENCY
No adjustment in dosage is required in patients with varying
degrees of renal insufficiency (creatinine clearances as low
as 9 mL/min) as pharmacokinetic studies did not indicate any
change in the disposition of finasteride.
DOSAGE IN THE ELDERLY
No adjustment in dosage is required although pharmacokinetic
studies indicated the elimination of finasteride is somewhat
decreased in patients more than 70 years of age.
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PRECAUTIONS |
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GENERAL
Hypersensitivity: Angioedema. See SIDE EFFECTS.
Patients with large residual urine volume and/or severely
diminished urinary flow should be carefully monitored for
obstructive uropathy.
EFFECTS ON PSA AND PROSTATE CANCER DETECTION
No clinical benefit has yet been demonstrated in patients
with prostate cancer treated with PROSCAR. Patients with BPH
and elevated prostate-specific antigen (PSA) were monitored
in controlled clinical studies with serial PSAs and prostate
biopsies. In these studies, PROSCAR did not appear to alter
the rate of prostate cancer detection. The overall incidence
of prostate cancer was not significantly different in patients
treated with PROSCAR or placebo.
Digital rectal examinations as well as other evaluations for
prostate cancer are recommended prior to initiating therapy
with PROSCAR and periodically thereafter. Serum PSA is also
used for prostate cancer detection. Generally, a baseline
PSA >10 ng/mL (Hybritech) prompts further evaluation and
consideration of biopsy; for PSA levels between 4 and 10 ng/mL,
further evaluation is advisable. There is considerable overlap
in PSA levels among men with and without prostate cancer.
Therefore, in men with BPH, PSA values within the normal reference
range do not rule out prostate cancer, regardless of treatment
with PROSCAR. A baseline PSA < 4 ng/mL does not exclude
prostate cancer.
PROSCAR causes a decrease in serum PSA concentrations by approximately
50% in patients with BPH, even in the presence of prostate
cancer. This decrease in serum PSA levels in patients with
BPH treated with PROSCAR should be considered when evaluating
PSA data and does not rule out concomitant 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 the 4-year, double-blind,
placebo-controlled PROSCAR Long-Term Efficacy and Safety Study
(PLESS) confirmed that in typical patients treated with PROSCAR
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 increase in PSA levels of patients treated with
finasteride should be carefully evaluated, including consideration
of non-compliance to therapy with PROSCAR.
Percent free PSA (free to total PSA ratio) is not significantly
decreased by PROSCAR. The ratio of free to total PSA remains
constant even under the influence of PROSCAR. When percent
free PSA is used as an aid in the detection of prostate cancer,
no adjustment to its value is necessary.
DRUG/LABORATORY TEST INTERACTIONS
EFFECT ON LEVELS OF PSA
Serum PSA concentration is correlated with patient age and
prostatic volume, and prostatic volume is correlated with
patient age. When PSA laboratory determinations are evaluated,
consideration should be given to the fact that PSA levels
decrease in patients treated with PROSCAR . In most patients,
a rapid decrease in PSA is seen within the first months of
therapy, after which time PSA levels stabilize to a new baseline.
The posttreatment baseline approximates half of the pre-treatment
value. Therefore, in typical patients treated with PROSCAR
for six months or more, PSA values should be doubled for comparison
to normal ranges in untreated men. For clinical interpretation,
see PRECAUTIONS, EFFECTS ON PSA AND PROSTATE CANCER DETECTION.
PREGNANCY
PROSCAR is contraindicated for use in women when they are
or may potentially be pregnant (See CONTRAINDICATIONS).
EXPOSURE TO FINASTERIDE - RISK TO MALE FETUS
Women should not handle crushed or broken tablets of PROSCAR
when they are or may potentially be pregnant because of the
possibility of absorption of finasteride and the subsequent
potential risk to a male fetus (see PREGNANCY). PROSCAR tablets
are coated and will prevent contact with the active ingredient
during normal handling, provided that the tablets have not
been broken or crushed.
NURSING MOTHERS
PROSCAR is not indicated for use in women.
It is not known whether finasteride is excreted in human milk.
PEDIATRIC USE
PROSCAR is not indicated for use in children.
Safety and effectiveness in children have not been established.
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DRUG
INTERACTIONS |
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No drug interactions of clinical importance have been identified.
PROSCAR does not appear to affect significantly the cytochrome
P450-linked drug metabolizing enzyme system. Compounds which
have been tested in man have included propranolol, digoxin,
glyburide, warfarin, theophylline, and antipyrine and no clinically
meaningful interactions were found.
OTHER CONCOMITANT THERAPY
Although specific interaction studies were not performed,
in clinical studies PROSCAR was used concomitantly with ACE-inhibitors,
acetaminophen, acetylsalicylic acid, alpha-blockers, beta-blockers,
calcium channel blockers, cardiac nitrates, diuretics, H2
antagonists, HMG-CoA reductase inhibitors, nonsteroidal anti-inflammatory
drugs (NSAIDS), quinolones, and benzodiazepines without evidence
of clinically significant adverse interactions.
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SIDE
EFFECTS |
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PROSCAR is well tolerated.
In PLESS, 1524 patients treated with PROSCAR 5 mg daily and
1516 patients treated with placebo were evaluated for safety
over a period of 4 years. 4.9% (74 patients) were discontinued
from treatment due to side effects associated with PROSCAR
compared with 3.3% (50 patients) treated with placebo. 3.7%
(57 patients) treated with PROSCAR and 2.1% (32 patients)
treated with placebo discontinued therapy as a result of side
effects related to sexual function, which were the most frequently
reported side effects.
The only clinical adverse reactions considered possibly, probably
or definitely drug related by the investigator, for which
the incidence on PROSCAR was ³1% and greater than placebo
over the 4 years of the study, were those related to sexual
function, breast complaints and rash. In the first year of
the study, impotence was reported in 8.1% of patients treated
with PROSCAR vs. 3.7% of those treated with placebo; decreased
libido was reported in 6.4 vs. 3.4%, and ejaculation disorder
in 0.8 vs. 0.1%, respectively. In years 2-4 of the study,
there was no significant difference between treatment groups
in the incidences of these three effects. The cumulative incidences
in years 2-4 were: impotence (5.1% on PROSCAR, 5.1% on placebo);
decreased libido (2.6%, 2.6%); and ejaculation disorder (0.2%,
0.1%). In year 1, decreased volume of ejaculate was reported
in 3.7 and 0.8% of patients on PROSCAR and placebo, respectively;
in years 2?4 the cumulative incidence was 1.5% on PROSCAR
and 0.5% on placebo. In year 1, breast enlargement (0.5%,
0.1%), breast tenderness (0.4%, 0.1%) and rash (0.5%, 0.2%)
were also reported. In years 2-4 the cumulative incidences
were: breast enlargement, (1.8%, 1.1%); breast tenderness,
(0.7%, 0.3%); and rash (0.5%, 0.1%).
The adverse experience profile in the 1-year, placebo-controlled,
Phase III studies and the 5-year extensions, including 853
patients treated for 5-6 years, was similar to that reported
in years 2-4 in PLESS. There is no evidence of increased adverse
experiences with increased duration of treatment with PROSCAR.
The incidence of new drug-related sexual adverse experiences
decreased with duration of treatment.
The following additional adverse effects have been reported
in post-marketing experience:
hypersensitivity
reactions, including pruritus, urticaria and swelling of the
lips and face
testicular
pain.
LABORATORY TEST FINDINGS
When PSA laboratory determinations are evaluated, consideration
should be given to the fact that PSA levels are decreased
in patients treated with PROSCAR (See PRECAUTIONS).
No other difference in standard laboratory parameters was
observed between patients treated with placebo or PROSCAR.
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OVERDOSAGE |
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Patients
have received single doses of PROSCAR up to 400 mg and multiple
doses of PROSCAR up to 80 mg/day for three months without
adverse effects.
No specific treatment of overdosage with PROSCAR is recommended.
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AVAILABILITY |
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To be filled in locally.
STORAGE AND HANDLING
Store below 30°C (86°F) and protect from light.
Women should not handle crushed or broken tablets of PROSCAR
when they are or may potentially be pregnant (see CONTRAINDICATIONS,
PREGNANCY, and EXPOSURE TO FINASTERIDE - RISK TO MALE FETUS).
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