TRH's uterine drugs; 4.8 Flashcards
What category of drugs is used to either promote labor or to limit bleeding post-labor?
Oxytocics
What are three types of oxytocics?
Oxytocin analogs
Prostaglandins
Ergots
Oxytocin analogs obviously work on oxytocin receptors (OTRs). What kind of receptor is this? Where are they in the body?
OTRs are Gq receptors
OTRs are present in myoepithelial cells of mammary gland, pregnant myometrium, and CNS
What is required for OTRs to function?
Well, clearly oxytocin, but also Mg++ and cholesterol
What is the pharmacology utility of oxytocin analogs?
Uterine contractions
Milk let-down
Antidiuretic and vasoactive at high concentrations (ADH-like)
What kind of hormone is oxytocin (and its analogs)? What does this mean about administration?
Oxytocin is peptide hormone…so it canNOT be given orally
What enzyme of uterine/placental origin degrades oxytocin?
Oxytocinase…causes oxytocin (and analogs?) to be broken faster at pregnancy term
What is the name of the synthetic oxytocin?
Pitocin
When is pitocin used?
Drug of choice for labor induction
Milk let-down postpartum
Stimulation of uterine motility postpartum to reduce bleeding
When shouldn’t pitocin be used?
As an abortifacient
When there is cephalo-pelvic disproportion
Hypertonic uterine contractions
Use in women w/ previous C-sections (increased risk of uterine rupture)
What is the role of prostaglandins during labor?
Uterine contractions and hyperalgesia
What is the hormonal control of prostaglandins (PGs)?
Progesterone → decreased PGs
Estrogen → increased PGs
What are three examples of PROSTaglandin drugs?
DinoPROSTone
CarboPROST
MisoPROSTol
Which PG drugs mimic PGE2?
Dinoprostone
Misoprostol
What PG does carboprost mimic?
PGF2α
How are PGs used?
Basically, they cause the cervix to ripen/dilate and for delivery of whatever is in the uterus (fetus/baby/mole)
How is carboprost given?
Carboprost is given IM
How is misoprostol given? What is typically given with it?
Misoprostol is given vaginally or orally with mifepristone (a progesterone receptor antagonist)
How do ergots work?
Ergots are potent smooth muscle stimulators
How are ergots obtained?
From a fungus that grows on rye
What are examples of ergots?
Ergonovine
Ergotamine
LSD
Which ergot is used to control postpartum bleeding by causing uterine contraction?
Ergonovine
What is ergotamine used for?
Ergotamine is used for migraine headaches…it causes blood vessels to contract
What is LSD used for?
To smell colors and taste music
What are tocolytics used for?
Tocolytics reduce uterine contractions
What are examples of tocolytics?
β2 agonist
MgSO4
OTR antagonist
NSAID
What do β2 agonist do?
Activates adenylyl cyclase → increased cAMP → activated PKA → Inhibited MLCK → NO phosphorylated myosin → NO contraction
What are the potential side effects of β2 agonist?
Elevate maternal BP and cause pulmonary edema
Cause hyperglycemia
Increase oxygen demand → can precipitate an MI
Which β2 agonists are used to reduce uterine contractility?
Terbutaline
Ritodrine
How does magnesium sulfate cause smooth muscle relaxation?
Mg++ competes with Ca++
How is MgSO4 administered? What is it used to prevent?
MgSO4 is given IV to prevent seizures associated with eclampsia
What is an example of an OTR antagonist?
AtOsiBAN
O for oxytocin…Oxytocin is BANned
When is atosiban used?
Atosiban delays labor
What is a key side effect of atosiban?
Increased fetal mortality
Which NSAID is used to reduce uterine contractility?
Indomethacin
