Drugs of pregnancy, labour and post partum care Flashcards
What is the half life of oxytocin?
5 minutes
What is the half life of misoprostol?
20-40 minutes
What is the half life of ergometrine?
30-120 minutes
What is a uterotonic?
Drugs that cause uterine contraction
What drug causes St Anthony’s fire?
Ergometrine
What is St Anthony’s fire?
Otherwise referred to as ergotism or ergot poisoning - it is a potential toxic side effect of ergometrine - due to ergot alkaloid toxicity - it can cause dry gangrene and convulsions
What is oxytocin?
A nanopetide produced in the hypothalamus and released by the posterior pituitary gland- it is a uterotonic - it stimulates uterine contraction
What is misoprostol?
A synthetic prostaglandin, an analogue of prostaglandin E1
Why is ergometrine regulated?
Chemically similar to LSD and can be used to manufacture LSD
What kind of drugs are carbegoline and bromocriptine?
D2 dopamine receptor agonists - they suppress prolactin and therefore can be used in treatment of prolactinomas and suppression of lactation
What kind of drug is prochlorperazine?
dopamine D2 receptor antagonist
What kind of drug is ondansetron?
serotonin 5HT3 antagonist
What kind of drug is cyclizine?
Histamine H1 receptor antagonist
What kind of drug is promethazine?
Histamine H1 receptor antagonist
What is carbergoline?
A D2 agonist used to suppress lactation (inhibits prolactin)
What is bromicriptine?
A D2 agonist used to suppress lactation (inhibits prolactin)
What is domperidone?
A dopamine antagonist - stimulates lactation
Morphine vs. diamorphine
diamorphine prodrug of morphine, more lipophilic, can cross blood brain barrier
Where is methadone stored in the fetus?
liver, lung, spleen
When are the symptoms of neonatal narcotic abstinence syndrome seen?
may occur in first 48 hours or can occur within 4 weeks (methadone is stored by fetal tissues - lung/liver/spleen)
Features of neonatal narcotic abstinence syndrome
iritability, poor feeding, hyperreflexia/hypertonic, high pitched cry, respiratory distress, seizures
What are the features of lidocaine anaesthesia toxicity?
perioral/tongue numbness metallic taste tinnitus blurred vision seizures or LOC widening PR/QRS Cardiovascular compromise cardiac toxicity
In which conditions would you avoid lidocaine?
patients with heart conditions particularly wPw syndrome
What are the features of wolf-Parkinson-white syndrome?
cardiac pre-excitation syndrome due to an accessory pathway (bundle of kent) - delta waves on ECG - predispose to risk of supraventricular tachycardias
Max dose of lidocaine with adrenaline?
7mg/kg
max dose of lidocaine without adrenaline?
3-5mg/kg
Which receptors does lidocaine act?
Fast-voltage gated sodium channels
How does clomifene affect fertility?
selective oestrogen receptor modulator
Blocks oestrogen receptors of the hypothalamus
Leads to reflex increase in Gnrh and therefore FSH/LH
What receptor type does oxytocin bind to?
G-couple protein receptors
Preferred first line treatment of hyperthyroidism in pregnancy
propylthiouracil
Carbimazole crosses the placenta too easily and is associated with congenital abnormalities (choanal atresia, aplasia cutis)
Which drug is an oxytocin receptor antagonis?
atosiban
What molecules are required for oxytocin receptor functioning?
cholesterol and magnesium
Hypothesised action of oxytocin on fetal brain
reduces effect of hypoxic insult by inducing a switch of GABA signalling from excitatory to inhibitory
Side effects of oxytocin
hypertension, tachycardia, increased cardiac output
Can cause arrythmia
can cause uterine rupture
can have same effect as ADH and cause oliguria, water intoxication
risk of seizure and subarachnoid haemorrhage
What are prostaglandins derived from?
fatty acids
What is prostaglandin E1 used for?
misoprostol (synthetic prostaglandin E1) is used for PPH and termination of pregnancy
What is prostaglandin E2 used for?
Dinoprostone is used for induction of labour (cervical ripening)
What is prostaglandin F2alpha used for?
Dinoprost or carboprost is used for termination of pregnancy, induction of labour and PPH
What is dinoprost?
a naturally occurring prostaglandin (F alpha)
What is carboprost?
synthetic prostaglandin F alpha
used for termination/PPH/induction of labour
What is dinoprostone?
naturally occurring prostaglandin E2 used in labour induction
Non-uterine use of misoprostol
synthetic prostaglandin E1 is also used in gastric acid prevention by inhibition of adenylate cyclase in parietal cells
Which prostaglandin is associated with transient hyperthermia?
dinoprostone (E2) analogue
What are the different tocolytic mechanisms?
oxytocin receptor antagonist
calcium channel blocker
NSAIDs
Beta 2 agonists
How is atosiban administered?
IV
