DRUGS USED IN PREGNANCY

Question 1

What are oxytocics?

Answer 1

Stimulate the uterus to contract
- induction and augmentation of labour
- reduces risk of postpartum hemorrhage

Question 2

What are tocolytics?

Answer 2

Inhibits uterine contractions
- premature labour
- uterine hypertonus

Question 3

What is smooth muscle contraction initiated by?

Answer 3

Gi protein coupled receptors
- decreased cAMP
- less protein kinase, less phosphorylation of Ca+ sequestering proteins

Gq protein coupled receptors
- increased IP3, stimulates Ca2+ release from the sarcoplasmic reticulum into the cytoplasm
- increased DAG, moves extra cellular calcium into the smooth muscle cell

Question 4

What is oxytocin?

Answer 4

Binds to Gq protein coupled receptor (GPCR), increases frequency and force of uterine contractions

No biological effect until oxytocin receptors are present in the myometrium, oxytocin receptors do not appear until the 2nd half of gestation

Question 5

What is pitocin, syntocinon (agonist drugs) administered IV?

Answer 5

Uterine response occurs almost immediately and subsides within one hour (induction of augmentation of labor)

Question 6

What is pitocin, syntocinon (agonist drugs) administered IM?

Answer 6

Uterine response occurs within 3-5 minutes and persists for 2-3 hours (control of post partial hemorrhage)

Question 7

When should oxytocin infusion be stopped?

Answer 7

When there is fetal stress and maternal complications

Question 8

What is prostaglandin agonists (oxytocics)?

Answer 8

Can induce contraction at anytime during pregnancy

Question 9

What is dinoprostone (oxytocics)?

Answer 9

ripens cervix and initiation of labor

Question 10

What is Ergot Alkaloids?

Answer 10

Control of post partum hemorrhage
Second line treatment of postpartum hemorrhage (after first line:oxytocin)
Causes contraction of smooth muscle in both the uterus and blood vessels

Question 11

What is uterine hypertonus?

Answer 11

Serious adverse effect of oxytocic drug therapy
Hypertonus can asphyxiate the fetus and cause uterine rupture

Question 12

What is a tocolytic drugs?

Answer 12

Any drug that decreases intracellular calcium levels in uterine smooth muscle and reduces the strength of uterine contractions

To be used 24-34 weeks gestation

Used when pt is having contractions lasting longer than 45 seconds and occur 2-10 mins apart

Question 13

What do tocolytic drugs allow for ?

Answer 13

• administration of glucocorticoids
• delivery at a facility with access to neonatal ICU
• prolonged pregnancy in cases of underlying self limiting conditions that are unlikely to cause recurrent preterm labour

Question 14

What does glucocorticoid therapy do?

Answer 14

Improve fetal lung development; improving outcome
Reduces risk of respiratory distress syndrome, bleeding in brain, sepsis

Question 15

What is a prostaglandin inhibitor (NSAIDs) - indomethacin?

Answer 15

Inhibits prostaglandin synthesis via inhibition of COX1 and COX2 enzymes
Stops oxytocin from binding to endometrium and myometrium

Question 16

What is Nifedipine (calcium channel antagonist)?

Answer 16

Inhibits the entry of extra cellular calcium into myometrial cells and slows uterine contractions
May also be used for severe pregnancy induced hypertension, although labetaolol is the preferred treatment

Question 17

What is magnesium sulphate?

Answer 17

Poor choice for tocolysis, but effective at managing eclampsia
Can be used for fetal neuroprotection in imminent preterm birth

Question 18

What is indomethacin?

Answer 18

First line therapy for tocolysis in cases of preterm labour between 24 and 32 weeks gestation