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Old 10-30-2010
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Drug question - GnRH analog

PATIENT PROFILE - 59 yo male with 2 month hx of back pain, not relieved with over-the-counter pain relievers. Pain worse at night and interferes with sleep, tenderness at lumbar vertebrae, digital rectal exam reveals enlarged and firm prostate.
Rx – you start him on leuprolide
QUESTION – which of the following changes in testosterone(T) and dihydrotestosterone (DHT) levels are most likely to occur?
A no change
B discordant decrease in DHT levels
C steady decrease in T and DHT
D first discordant increase, then discordant decrease in DHT level
E first concordant increase , then concordant decrease in T and DHT levels

please expalin your answer too
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Old 10-31-2010
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no one attempted this question after 80 views
the objective of these questions is to self-study for me and i have noticed that you folks know a whole lot more than me
i will request you folks to share your knowledge with me please

Ans – pulsatile release of gonadotropin-releasing hormone (GnRH) from hypothalamus is the natural state of human functioning causing release of gonadotropins from pituitary that in turn stimulates release of testosterone in man
Testosterone is converted to DHT in target tissues by enzyme 5-alpha reductase
Alternately, if GnRH levels are constantly elevated rather than pulsed, the secretion of LH and FSH from pituitary will be suppressed
A number of GnRH analogs, such as leuprolide, have been generated by amino acid substitutions-alterations that allow longer half lives and increased activity
Leuprolide is a long-acting GnRH analog that causes continuous GnRH activity
The result is ultimately suppression of pituitary-gonadal axis for the duration of Rx, although there is a brief period of initial stimulation, sometimes called “start up flare”
An increase in gonadotropin levels during the initial flare up period causes increase in both T and DHT levels (concordant increase)
Soon the start up flare burns out and both T and DHT are typically suppressed to castrate levels
These very low levels of androgens are useful for Rx of androgen-dependant cancers, such as prostate
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Old 10-31-2010
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Thanks for the question & the nice explanation.
Knowing is not enough; we must apply.
Willing is not enough; we must do.
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Pharmacology-, Step-1-Questions

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