Browse Prescribing Notes by Therapeutic Subcategory

For antibiotics for urinary tract infections see Bacterial infections section.

Two classes of drugs are approved for the treatment of BPH: 5α-reductase inhibitors and α-blockers. The 5α-reductase inhibitors (dutasteride, finasteride) are indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) to improve symptoms, to reduce the risk of acute urinary retention, and to reduce the risk of the need for surgery, including transurethral resection of the prostate (TURP) and prostatectomy. These drugs alleviate urinary obstruction by blocking the formation of dihydrotestosterone (DHT) and thereby induce the shrinkage of hyperplastic prostate tissue. Potential side effects include impotence, decreased libido or ejaculate volume, and gynecomastia. Men taking 5α-reductase inhibitors should not donate blood until at least 6 months after their last dose to prevent pregnant women from receiving these medications through a blood donation. 5α-reductase inhibitors are contraindicated in women because they inhibit the conversion of testosterone to DHT, which may cause abnormalities of the external genitalia of a male fetus. Both of these drugs can be absorbed through the skin and into the blood. Women who are or may be pregnant should not handle crushed or broken finasteride tablets or leaking dutaseride capsules because of the possibility of absorption and the subsequent potential risk to a male fetus.
The α-blockers (alfuzosin, doxazosin, tamsulosin, terazosin) are indicated for the symptomatic treatment of urinary obstruction caused by BPH. They block sympathetic activity and relax the smooth muscle component of prostatic hypertrophy. The α-blockers are generally well-tolerated. The most common side effects are orthostatic hypotension, dizziness, asthenia, lightheadedness, ejaculation disorders, and, rarely, priapism may occur. These side effects can be minimized or avoided by taking these medications at bedtime and starting at low doses and titrating slowly. If these drugs are discontinued for more than a few days the patient should be re-titrated from the initial dose.