Review of Pharmacology - 9E (2015)

Review of Pharmacology
• Androgen receptor inhibitors: Cyproterone and cyproterone acetate act as
antagonists of androgen receptors. Latter compound has marked progestational
activity that inhibits feedback enhancement of LH and FSH. These drugs are useful
in the treatment of hirsutism and as a component of contraceptive pills. Flutamide,
bicalutamide, enzalutamide and nilutamide are other anti-androgens that act by
same mechanism. These are useful for the treatment of prostatic carcinoma. Flutamide
can cause gynaecomastia and reversible liver damage. These drugs can also be combined
with GnRH agonists (like leuprolide) to reduce the initial flare up reaction.
• Spironolactone: It is an aldosterone antagonist that also competes with DHT for its
receptor. It can be used for the treatment of hirsutism.
Endocrinology
UTERINE STIMULANTS
These drugs increase uterine contractions and are known as oxytocics or ecbolics.
Oxytocin
It is secreted by posterior pituitary along with ADH. It increases the uterine contractions with
complete relaxation in between. It increases the contraction of upper segment (fundus and body) of
uterus whereas lower segment is relaxed facilitating the expulsion of the fetus. Estrogen increases
whereas progesterone decreases the sensitivity of uterus to oxytocin.
• Oxytocin is involved in milk ejection reflex whereas prolactin causes milk secretion.
• High doses of oxytocin cause fall in BP (due to vasodilation) resulting in reflex
tachycardia.
• It also has ADH like action in high dose and can result in fluid retention.
Uses
It is used for the induction of labor in post-maturity and uterine inertia. It can also be
used for the treatment of postpartum hemorrhage but methyergometrine is preferred for
this indication. Oxytocin challenge test is performed to know the adequacy of uteroplacental
circulation in high risk pregnancies.
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Adverse effects
Injudicious use may result in rupture of uterus due to powerful uterine contractions. It may
also cause water intoxication due to ADH like action. Oxytocin should not be used in cases of
contracted pelvis, obstructed labour, malpresentation, history of LSCS, hypovolemic states and cardiac
disease.
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