9.5 Drugs in Labour

Question 1

What secretes oxytocin?

Answer 1

posterior pituitary

Question 2

Where is oxytocin produced?

Answer 2

hypothalamus

Question 3

What roles does oxytocin have?

Answer 3

• ripening cervix
• contractions of uterus
• breastfeeding myoepithelial cells “let-down” / contract to release milk

Question 4

When are infusions of oxytocin used?

Answer 4

• induce labour
• progress labour
• improve freq. and strength of contractions
• prevent of treat PPH

Question 5

What is a brand name of oxytocin?

Answer 5

Syntocinon

Question 6

What is a oxytocin receptor antagonist and when might you use it?

Answer 6

Atosiban is oxytocin receptor antagonist

for TOCOLYSIS in premature labour (when nifedipine is CI)

Question 7

What is often used after delivery in the 3rd stage to prevent / reduce PPH?

Answer 7

Ergometrine - stimulates smooth muscle contraction

Question 8

What are the side effects of ergometrine?

Answer 8

• HTN
• diarrhoea
• vomiting
• angina

Question 9

When is ergometrine CI?

Answer 9

CI in eclampsia and caution with in HTN.

Question 10

What is the name of ergometrine mixed with oxytocin for PPH?

Answer 10

Syntometrine

Question 11

What effect do prostaglandins have on the body?

Answer 11

• stimulate contraction of uterus
• ripen cervix
• vasodilator

Question 12

What is the name of the prostaglandin used in IOL?

Answer 12

dinoprostone or prostaglandin E2

Question 13

What forms can dinoprostone come in?

Answer 13

pessaries - Propess
tablets - Prostin
gel- Prostin

(prostaglandin E2)

Question 14

What medication opposes the action of prostaglandins?

Answer 14

NSAIDs inhibit action of prostaglandins

Question 15

What can NSAIDs be used for?

Answer 15

• avoid in pregnancy, can raise BP

- useful in dysmenorrhea as they reduce painful cramping

Question 16

What drug is a prostaglandin analogue?

Answer 16

Misoprostol is a prostaglandin analogue

Question 17

What is misoprostol used for?

Answer 17

• medical management of miscarriage
• alongside mifepristone for abortions
• IOL after IUD

Question 18

What is the MOA of mifepristone?

Answer 18

anti-progestogen (blocks progesterone action) so:
- halts pregnancy and ripens cervix
enhances effects of prostaglandins so:
- stimulates contractions of uterus

Question 19

What is mifepristone used for?

Answer 19

• alongside misoprostol for abortions

- IOL after IUD

Question 20

What two uses does nifedipine have?

Answer 20

• reduce BP in HTN of PET
• tocolysis in prem labour

(calcium channel blocker reduces smooth muscle contraction in vessels and uterus)

Question 21

What is the MOA of terbutaline?

Answer 21

beta-2 agonist (similar to salbutamol)
Stimulates beta-2 ADR receptors

• acts on smooth muscle of uterus to suppress contractions –> tocolytic

Question 22

When is terbutaline used?

Answer 22

tocolysis in uterine hyperstimulation eg excessive contractions during IOL

Question 23

What is the MOA of carboprost?

Answer 23

synthetic prostaglandin analogue

Question 24

What is carboprost used for?

Answer 24

deep IM injection in PPH when ergometrine and oxytocin have been inadequate.

Question 25

When should carboprost be avoided?

Answer 25

In patients with a history of asthma - can trigger life threatening exacerbation

Question 26

What is the MOA of tranexamic acid?

Answer 26

antifibrinolytic

it binds to plasminogen and prevents in converting to plasmin (plasmin enzyme breaks down fibrin clots)

Question 27

What is tranexamic acid used for in labour?

Answer 27

prevent and treat PPH.

prevents breakdown of clots by blocking plasmin formation