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 EFFECTS ON PSA AND PROSTATE CANCER DETECTION as previously mentioned.
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 USE IN 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.
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.
Breast cancer in men: Breast cancer has been reported in men taking finasteride 5 mg during clinical trials and in the post-marketing period. Physicians should instruct their patients to promptly report any changes in their breast tissue such as lumps, pain, gynaecomastia or nipple discharge.
Use in 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.
Use in Lactation: PROSCAR is not indicated for use in women.
It is not known whether finasteride is excreted in human milk.
Use in Children: PROSCAR is not indicated for use in children.
Safety and effectiveness in children have not been established.