Oxytocics and Tocolytics Flashcards Preview

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Flashcards in Oxytocics and Tocolytics Deck (11):
1

Oxytocics

drugs that stimulate uterine smooth muscle to contract
- induce labor, control post-partum hemorrhage

2

Tocolytics

any drug used to suppress uterine smooth muscle and suppress labor

3

Smooth muscle contraction and Ca

GPC -> PLC -> PIP2 -> IP3 and DAG -> Ca influx
- MLC kinase -> cross-bridge facilitated by Ca-calmodulin
- Ca actively pumped out of cell
- MLC and dephosphorylated by MLCPas

4

Oxytocin

synthesized in paraventricular nucleus of hypothalamus
- released from vesicles in response to cervical dilation, stimulation of vagina, suckling
- Oxytocin receptor (GPCR) -> PLC
Absorption and Excretion - parenteral and sublingual -> can't be given orally

5

Pitocin

synthetic oxytocin -> drug of choice for labor induction
- milk let down post-partum
- stimulation of uterine motility to reduce bleeding
Contraindications -> cephalo-pelvic disproportion, hypertonic uterine contractions

6

Prostaglandins

PLA2 -> releases arachidonic acids from phospholipids
- accomplished by COX pathway
- function close to site of synthesis and are deactivated to inactive metabolites
- levels rise in amniotic fluid during parturition, induces contractions, promotes cervical ripening
INDOMETHACIN -> reduces oxytocin induced uterine contractions through reducing PG production

7

PG Drugs

Dinoprostone -> natural PGE
Misoprostol -> synthetic PGE
Dinoprost -> natural PGF2
Carboprost -> PGF2 (injection)

8

Ergots

alkaloids from fungus
- potent smooth muscle stimulating properties are capitalized in medicine
Ergonovine/Ergometrine -> contraction of uterus
Ergotamine -> contraction of blood vessels

9

Tocolytics (beta2 agonists)

beta 2 selective agents -> activate adenylyl cyclase and raises cAMP
TERBUTALINE -> given after 20th week
- increase HR, pulmonary edema, hyperglycemia, MI
Magnesium sulfate -> competes with Ca and relaxes smooth muscle -> prevents seizures associated with eclampsia

10

Oxytocin Receptor Antagonist

Atosiban -> only oxytocin receptor antagonist approved for use
- inhibits OTR inositol trisphosphate activation
- delays labor, rapid onset
- increased fetal mortality

11

INDOMETHACIN

non-selective inhibitor of COX 1 and 2 -> blocks PG formation
- for short-term delay of labor