Drugs in Labour

Question 1

What are the roles of oxytocin in labour?

Answer 1

• it stimulates ripening of the cervix

AND

• contractions of the uterus during labour / delivery

Question 2

When are infusions of oxytocin given in labour?

Answer 2

• for induction of labour
• to progress labour
• to increase the frequency / strength of uterine contractions
• to prevent / treat PPH

Question 3

What “brand name” is used for oxytocin?

Answer 3

syntocinon

Question 4

What type of drug is atosiban?

Answer 4

oxytocin receptor antagonist

Question 5

When is atosiban used?

Answer 5

• used as an alternative to nifedipine
• this is used for tocolysis in premature labour

Question 6

How does ergometrine work?

What is it used for?

Answer 6

• it stimulates smooth muscle contraction in the blood vessels / uterus
• it is used for delivery of the placenta and to reduce postpartum bleeding

Question 7

When can ergometrine be used?

Answer 7

• it is only used after delivery of the baby (in the third stage)
• it can also be used postpartum to prevent / treat PPH

Question 8

What are the side effects associated with ergometrine?

Answer 8

• angina
• diarrhoea
• vomiting
• hypertension

this is due to its effects on smooth muscle in blood vessels in the GI tract

Question 9

What are the contraindications to ergometrine?

Answer 9

• eclampsia is an absolute contraindication
• used with extreme caution in patients with hypertension

Question 10

What is syntometrine?

Answer 10

• a combination drug containing oxytocin + ergometrine
• used for the prevention / treatment of PPH

Question 11

Why are prostaglandins given in labour?

Answer 11

• stimulation of uterine muscles
• ripening of the cervix prior to delivery

Question 12

What is the main prostaglandin used in labour?

Answer 12

prostaglandin E2 (dinoprostone)

• used for induction of labour
• can be a tablet, gel or pessary

Question 13

What type of drug is misoprostol?

Answer 13

prostaglandin analogue

• it binds to / activates prostaglandin receptors
• this stimulates uterine contractions
• it is used in treatment of miscarriage / abortion / IOL after IUFD

IUFD = intrauterine fetal death

Question 14

What type of drug is mifepristone?

Answer 14

anti-progestogen

• it blocks the action of progesterone
• this halts the pregnancy + ripens the cervix
• it is used in abortion + IOL after IUFD

Question 15

What type of drug is nifedipine?

Answer 15

calcium channel blocker

• it reduces smooth muscle contraction in blood vessels + uterus

Question 16

What are the 2 roles for nifedipine in pregnancy?

Answer 16

• reducing BP in hypertension / pre-eclampsia
• tocolysis in premature labour by reducing uterine activity / contractions

Question 17

What type of drug is terbutaline?

Answer 17

beta-2 agonist

• it acts on beta-2 adrenergic receptors to suppress uterine contractions

Question 18

When is terbutaline used?

Answer 18

• used for tocolysis in uterine hyperstimulation
• this occurs when uterine contractions become excessive following IOL

Question 19

What type of drug is carboprost?

Answer 19

synthetic prostaglandin analogue

• it binds to prostaglandin receptors / activates them
• this stimulates uterine contractions

Question 20

When is carboprost used?

Answer 20

• it is given as a deep IM injection in postpartum haemorrhage
• it is given when syntometrine has been inadequate

Question 21

What are the contraindications for carboprost?

Answer 21

• avoid / use with caution in asthma
• can cause life-threatening asthma exacerbations

Question 22

What type of drug is tranexamic acid?

Answer 22

antifibrinolytic

• it binds to plasminogen to prevent it converting to plasmin
• plasmin dissolves the fibrin within blood clots

Question 23

When is tranexamic acid used?

Answer 23

• it helps to prevent the breakdown of blood clots
• this is used in the prevention / treatment of PPH