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 Proscar
( finasteride, MSD )
PROSCAR® (finasteride, MSD), a synthetic 4-azasteroid compound is a specific inhibitor of Type
II 5α-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.
INDICATIONS
• PROSCAR is indicated for the treatment and control of benign prostatic hyperplasia (BPH) and
for the prevention of urologic events to:
-- Reduce the risk of acute urinary retention.
-- Reduce the risk of surgery including transurethral resection of the prostate (TURP) and
prostatectomy.
• PROSCAR causes regression of the enlarged prostate, improves urinary flow and improves the
symptoms associated with BPH.
Patients with an enlarged prostate are the appropriate candidates for therapy with PROSCAR.
PROSCAR administered in combination with the alpha-blocker doxazosin is indicated to reduce
the risk of symptomatic progression of BPH (a confirmed 4 point increase in ALA symptom
score).
DOSAGE AND ADMINISTRATION
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.
CONTRAINDICATIONS
PROSCAR is not indicated for use in women or children.
PROSCAR is contraindicated in the following:
• Hypersensitivity to any component of this product.
• Pregnancy - Use in women when they are or may potentially be pregnant (see PRECAUTIONS.
PREGNANCY and EXPOSURE TO FINASTERIDE - RISK TO MALE FETUS).
PRECAUTIONS
GENERAL
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 BPH studies, PROSCAR
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 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. 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 post treatment 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).
Because of the ability of Type II 5α-reductase inhibitors to inhibit conversion of testosterone to dihydrotestosterone, these drugs, including finasteride, may cause abnormalities of the external
genitalia of a male fetus when administered to a pregnant woman.
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 riot
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.
SPECIAL PRECAUTION
Urethral stricture, infection, cancer, hypotonic bladder and other neurogenic disorders should be
excluded before treatment with finasteride is started.
Caution is advised in treating patients with hepatic dysfunction since the drug is extensively metabolised in the liver.
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