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MEDICATION FOR BPH : LHRH AGONISTS (LUPRON, ZOLADEX)
30 March 2009
by
admin
Filed under
Men's Health-Erectile Dysfunction
Testosterone is made in the testes, but it’s the pituitary gland that really calls the shots: The pituitary gland transmits a chemical signal, called luteinizing hormone (LH), which motivates the testes to make testosterone. But LH can be blocked by a synthetic analog (a chemical look-alike that acts differently) of another of the body’s chemical messengers. This messenger is called LHRH (for luteinizing hormone-releasing hormone; it’s also called GnRH, for gonadotropin-releasing hormone).
Here’s how it works: LHRH, made in the brain by the hypothalamus, is dispatched in signal pulses—like Morse code or flashes of light—to the nearby pituitary gland. These pulses tell the pituitary to make LH. The powerful synthetic analogs called LHRH agonists work by providing prolonged stimulation—by turning on the light and keepingit on, for example, instead of just flashing the light. So these drugs trick the pituitary: Because the pituitary receives no flashes, or pulses, it thinks no signal is being sent. And it doesn’t make LH. It’s like a chess game, and LHRH agonists effectively put LH—and therefore, testosterone—in checkmate.
Why is it so important to stop production of testosterone? Testosterone, not in itself the prime culprit of BPH, represents just one step in a chain of chemical interactions involved in BPH—but it’s a big one. One of the most convincing demonstrations is the study in which scientists achieved a “chemical castration,” by suppressing testosterone in patients with BPH. They found that prostate size decreased by an average of 25 percent, reaching a plateau after about four months. When they reversed the chemical castration—by allowing testosterone production to resume—prostates returned to their former size.
That’s how LHRH agonists work, by shutting down testosterone. They do help BPH symptoms—in the above study, for example, one-third of the men had improved rates of urinary flow—and they may be an option for men who are not candidates for surgery. But as with any medication that must be taken regularly (as shots once a month), beginning this kind of therapy means assuming the cost of medication for years. Also, improvement is not immediate; it takes weeks or months before the prostate begins to shrink.
LHRH agonists are not standard therapy for BPH, mainly because in cutting the body’s levels of testosterone they cause impotence, hot flashes and weight gain. For BPH, such results are considered extreme and cause most men (except for those who are already impotent) and their doctors to wonder which is worse—the disease or the treatment. However, for an elderly man who has urinary retention and is not a candidate for other forms of treatment, an LHRH agonist may be successful and may act quicker than finasteride.
Of course, in prostate cancer—for which these drugs are mainly used—it’s a different story. Potency assumes a lower rung on the ladder of priorities in the face of a life-threatening disease.
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