Gonadotropin-releasing hormone analogues
Gonadotropin-releasing hormone analogues
Gonadotropin-releasing hormone analogues are used for treatment of advanced prostate cancer. They include:
- goserelin
- leuprolide
- triptorelin.
Pharmacokinetics
Goserelin is absorbed slowly for the first 8 days of therapy and rapidly and continuously thereafter. After subcutaneous injection, leuprolide is well absorbed. Neither drug’s distribution, metabolism, or excretion is defined clearly.
Triptorelin serum levels peak within 1 week of I.M. injection; the drug remains detectable in serum for 4 weeks.
Warning!
Adverse reactions to gonadotropin-releasing hormone analogues
Hot flashes, impotence, and decreased sexual desire are commonly reported reactions to gonadotropin-releasing hormone analogues. Other adverse reactions include:
- peripheral edema
- nausea and vomiting
- constipation
- anorexia.
Flares and flashes
Disease symptoms and pain may worsen or flare during the first 2 weeks of goserelin or leuprolide therapy. The flare can be fatal in patients with bony vertebral metastasis.
Triptorelin may cause hot flashes and skeletal pain. Less commonly, it may cause hypertension, diarrhea, vomiting, urine retention, and impotence.
Pharmacodynamics
Goserelin and leuprolide act on the male’s pituitary gland to increase luteinizing hormone (LH) secretion, which stimulates testosterone production. The peak testosterone level is reached about 72 hours after daily administration.
Running the reverse
With long-term administration, however, goserelin and leuprolide inhibit LH release from the pituitary and subsequently inhibit testicular release of testosterone. Because prostate tumor cells are stimulated by testosterone, the reduced testosterone level inhibits tumor growth.
Then there’s triptorelin
Triptorelin is a potent inhibitor of gonadotropin secretion. After the first dose, levels of LH, follicle-stimulating hormone (FSH), testosterone, and estradiol surge transiently. After long-term continuous administration, LH and FSH secretion steadily declines and testicular and ovarian steroid production decreases. In men, testosterone declines to a level typically seen in surgically castrated men. As a result, tissues and functions that depend on these hormones become inactive.
Pharmacotherapeutics
Goserelin, leuprolide, and triptorelin are used for the palliative treatment of metastatic prostate cancer. The drugs lower the testosterone level without the adverse psychological effects of castration or the adverse cardiovascular effects of diethylstilbestrol.
Drug interactions
No drug interactions have been identified with goserelin, leuprolide, or triptorelin.
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