Finasteride (Proscar®) is used to treat benign prostatic hypertrophy (prostatism) at a dose of 5 mg daily; it's quite effective, but it's known to interfere with blood levels of prostate specific antigen (PSA), so that physicians recommend that PSA levels be doubled when trying to interpret them in men on Proscar.

The same drug, finasteride, under the name Propecia®, is given at a dose of 1 mg daily to treat male-pattern hair loss. Does this dose also interfere with the prostate cancer test - PSA levels - too? Boston researchers decided to find out. Their report,

published in The Lancet Oncology

a few months ago, found that, in men aged 40 - 60 taking 1 mg Propecia for 48 weeks lowered the serum PSA level. The investigators therefore recommend that the adjustment to PSA levels used for men taking 5 mg daily of Proscar should also apply to men taking 1 mg daily of Propecia.

This result is an example of the risk of calling the same medication by different names for different indications. Another example is bupropion, which is sold as Wellbutrin® for depression, and Zyban® for helping to stop smoking. Or fluoxetine, sold as Sarafem® for premenstrual tension and Prozac® for depression and other indications. (These examples come from 2002; there may be newer ones since then!)

PSA levels are hard enough to interpret without having this added complication in some men. But they are definitely useful, when considered together with all the patient's other information. Men should have their PSA level tested annually after the age of 50.

Source
HealthandAge Blog