Chapter 10 endocrine system - oxytocin + other ob/gyn drugs

Question 1

oxytocin

Answer 1

• posterior pituitary
• induces contraction in gravid uterus (advanced stage of preg + abdominal cavity) =» desired when labor acceleration is desired
• chemically similar to vasopressin (which is also released in pituitary) — can also cause antidiuretic effects and fluid retention

Question 1

How to reduce uterine hemorrhage after delivery?

Answer 1

• use methyl-ergonovine after delivery to reduce uterine hemorrhage
• causes vasoconstriction, but mainly causes tonic uterine contraction
• force of muscle contraction impedes blood flow through uterus which reduces bleeding

Question 2

What is used for premature onset of labor with contractions?

Answer 2

• uterine relxants known as tocolytic agents
• b2 adrenergic agonists which reduce contractions

Question 3

3 pharmacologic strategies for treating infertility?

Answer 3

1) Gonadorelin – synthetic GnRH => stimulates FSH and LH production when administered in pulses
2) Clomiphene – is an antiestrogen which causes FH and LH release by reducing feedback inhibiton by estrogen on pituitary gland
3) Menotropins – FSH + LH purified from urine of postmenopausal women

• all have greater than 50% success rate in achieveing ovulation + risk of inducing multiple pregnancies

Question 4

oxytocin (pitocin)

uterine contraction stimulant

Answer 4

• inc force and frequency of uterine contraction
• most pronounced in near-term uterus
  other actions
• contraction inside mammary gland
• antidiuretic hormone (vasopressin)

indication
* induce or accerlate labor
* decrease postpartum uterine bleeding
* stimulate milk ejection from breast (nasal spray…?)

effects
* uterine tetany (A contraction that lasts longer than 90 seconds) or rupture
* infant trauma
* post delivery uterine atony (soft and weak uterus after childbirth)
* prolonged infusion (>24 hr) => l/t water intoxiciation (antidiuretic activity)

interactions
* potentiate antihypertensive effects of other drugs
* may l/t stroke + hemorrhage
* fetal distress

Question 5

ergonovine (ergotrate maleate)
methyl-ergonovine (methergine)

uterine contraction stimulant

Answer 5

• induce uterine smooth muscle contraction

other actions
1) blocks adrenergic receptors => causes vasoconstriction
2) interacts w/ o ther receptors (dopamine + tryptamine)
3) decreased lactation by dec prolactin levels

indication
* decrease uterine bleeding after abortion or parturition (giving birth)
* NOT FOR INDUCTION OF LABOR

effects
* HTN
* death of infant if given before prior to delievery
* fatal poisoning in pts w/ sensitiivty to ergot alkaloids

interactions
* potentiates HTN-sive meds
* may cause stroke/hemorrhage
* fetal distress

Question 6

carboprost trometamine (prostin/15M)
dinoprostone (prostin E2)

uterine contraction stimulant

Answer 6

• synthetic prostaglandin which stimulates uterine contraction

other actions:
regulate —
1) smooth muscle tone
2) coagulation
3) body temp

indications
* abortion during 2nd trimester
* FOR dinoprostone — help soften or ripen cervix prior to induction of labor

Mean time to abortion is 10-15 hours

effects
* incomplete abortion
* n/v
* fever
* uterine rupture
* perforation
* inflammation
* cramps
* CNS
* CV / resp complications

interactions
* potentiate HTN-sive effectives of other drugs
* may cause stroke or hemorrhage
* fetal distress

Question 7

terbutaline
ritodrine

uterine relaxant

Answer 7

b2 adrnergic reeptor preferring agonist
* dec uterine smooth muscle contraction

other actions
* inc glyconeolysis, tachycardia, gluconeogenesis, gut relaxation, vasodilation
* dec mast cells and neutrophils

indication
* prolong gestation in premature labor cases

IV/PO

effects
* hypotension
* tachycarida (reflex and b1 stimulated)
* for ritodrine…. more hypotension and tachycardia
* arrhythmias
* PE
* bradycardia w/ abrupt withdrawal
* muscle tremor

interactions
* w/ corticosteroids — inc’d diabetogenic effects
* inhalation anesthetics — inc hypotension

Question 8

magnesium

uterine relaxant

Answer 8

• decrease uterine contraction

other actions:
* dec neuromuscular conduction
* dec acetylcholine release
* vasodilation
* respiratory depression @ high doses

indication
* premature onset of labor
* pre-eclampsia (when pregnant women have high blood pressure, protein in their urine, and swelling in their legs, feet, and hands. It can range from mild to severe. It usually happens late in pregnancy, though it can come earlier or just after delivery.)
* eclampsia (In preeclampsia, the mother’s high blood pressure reduces the blood supply to the fetus, which may get less oxygen and fewer nutrients. Eclampsia is when pregnant women with preeclampsia develop seizures or coma)

IV (onset - seconds, duration 30 minutes)
IM — 1 hr onset, 3.5 hour duration

effects
* > 8 meq/l may cause depression of CNS, heart and reflexes
* flushing
* sweating
* hypotension
* flaccid paralysis

interaction
* additive CNS depresants
* potentiate neuromuscular blockers
* inc toxicity of digitalis

Excess Ca++ antagonizes Mg++ and is ued ocunter CNS and PNS depression

Question 9

gonadorelin

tx infertility

Answer 9

• synthetic GnRH
• administered IV in pulses spaced 90 mins apart
• each pulse => sstimulates FSH and LH release and result in ovulation in about 90% of women who have been tx’d
• rate of pregnancies was 12% in small series

////
* on the other hand, when administered continuously — GnRH analogs (e.g Lupron) suppress FSH and LH production by acting as feedback inhibitors

indication
* prostate cancer
* endometriosis ( disease in which tissue similar to the lining of the uterus grows outside the uterus. It can cause severe pain in the pelvis and make it harder to get pregnant. Endometriosis can start at a person’s first menstrual period and last until menopause.)

Question 10

clomiphene (clomid)

tx infertility

Answer 10

• stimulate LH and FSH release by reducing negative-feeedback by estrogen on the pituitary
• increased levels of above induce ovulation and matain functional corpus lutea (Although it’s inside your ovaries, the corpus luteum’s job is to make your uterus a healthy place for a fetus to grow. It releases a hormone called progesterone that prepares your uterus for pregnancy. Once it’s no longer needed to make progesterone, your corpus luteum goes away.)
• rate of pregnancy is 8%; abnormal ovarian enlargment occurs in 14% of pts l/t pain

Question 11

menotropins (pergonol)

tx infertility

Answer 11

• LH and FSH (purified from urine of postmenopausal women)
• administered for 9-12 days IM and followed by injection of chorionic gonadotropin (HCG is used in combination with other fertility drugs to increase a woman’s chance of pregnancy. In men or adolescent boys, HCG helps the production of testosterone and sperm. HCG is also used in male children with cryptorchidism, a specific birth problem of the testes)