What is BHP?
Benign Prostatic Hyperplasia (BPH) is a condition where the prostate gland becomes enlarged due to overgrowth of connective tissue within the prostate gland and also cells that form the lining of the gland. These cells are responsive to testosterone and also convert testosterone into the potent metabolite dihydrotestosterone or DHT, which in turn is thought to stimulate the growth of prostate cells, causing enlargement of the gland. This causes the prostate glad to expand pushing into the urethra, which is the tube taking urine from the bladder and this causes obstruction of urine flow and can cause urinary retention in the bladder. Increased muscle tone of smooth muscle cells in the prostate gland also causes compression of the urethra. Symptoms of BPH include need for frequent or urgent urination, inability to empty the bladder, urinary hesitancy (difficulty starting to urinate) and difficulty passing urine.
Medications for BPH
The medications available for treating BPH are used to reduce the symptoms of BPH by acting directly on cells of the prostate gland to relieve pressure on the urethra, or by blocking an enzyme involved in stimulation of prostate growth. These include:
- Alpha-blockers
- Inhibitors of DHT production
Alpha-blockers
Alpha-blockers, like terazosin and tamsulosin are also known as alpha-adrenergic antagonists. They work by binding to the alpha adrenergic receptor in smooth muscle cells, which blocks the action of naturally occurring adrenergic chemicals like noradrenaline that causes smooth muscle cells to contract and tighten. This allows the muscle in the prostate to relax and relieve pressure on the urethra; this also relaxes the neck of the urethra, which helps urine to flow more easily.
Inhibitors of DHT production
The conversion of testosterone to DHT is carried out in several tissues, including the prostate gland. This conversion is dependent on the action of the enzyme 5α-reductase, which exists in two forms, 5α-reductase I and 5α-reductase II. Drugs that inhibit this enzyme are used to treat BPH and include finasteride, which inhibits type II 5α-reductase and dutasteride inhibits the action of both forms (type I and type II) of the enzyme. 5α-reductase inhibitors reduce the amount of DHT in the prostate, so that growth is no longer stimulated allowing the enlarged prostate to shrink.
Dietary supplements for BPH
A dietary supplement containing an extract of berries from the Saw Palmetto plant, has anti-androgen similar to the 5α-reductase inhibitors and is used to help relieve symptoms of BHP.