Drugs in Pregnancy

Question 1

what is a teratogen?

Answer 1

• a substance which causes an abnormality within the baby following fetal exposure during pregnancy.
• usually discovered after increased prevalence of a particular birth defect.
• first half of pregnancy is the most vulnerable - affect embryogenesis.

Question 2

list some preventable teratogens

Answer 2

• alcohol - fetal alcohol syndrome
• smoking - low birth weight, preterm birth, cerebral palsy, learning difficulties
• marijuana, ecstacy, cocaine - low birth weight, withdrawal symptoms, learning and behavioural problems

Question 3

define pharmacokinetics

Answer 3

• what the body does to a drug
• movement of drug through, and out of the body
• the time course - absorption, bioavailability, distribution, metabolism, and excretion

Question 4

define pharmacodynamics

Answer 4

• what the drug does to the body
• biochemical/physiologic/molecular effects on drugs on body
• ## receptor binding/post receptor effect

Question 5

which drugs are used to treat nausea and vomiting during pregnancy?

Answer 5

• cyclizine - antihistamine
• prochloroperazine - phenothiazine
• doxylamine/pyridoxine combination product (Xonvea)
• second line - ondansetron, metoclopramide

Question 6

which drugs are used to treat hypertension during pregnancy? which drugs are teratogenic?

Answer 6

• labetolol, nifedipine, methyldopa, hydralazine
• teratogenic medicines - ACEi’s, angiotensin receptor anatgonist - change as soon as pregnancy confirmed

Question 7

which drugs are used to treat epilepsy during pregnancy? which drugs are teratogenic?

Answer 7

• carbamazepine and lamotrigine are the safest.
• always give high dose folic acid.
• teratogenic: phenobarbitone - cardiac malformations, sodium valproate - NTD, facial clefts

Question 8

what drugs are used to treat diabetes during pregnancy?

Answer 8

• insulin is the safest
• gestational diabetes/type-2 > metformin

Question 9

which drugs can be used to treat thromboembolism in pregnancy? which cannot?

Answer 9

• LMWH safe
• teratogenic: warfarin, potentially DOACs e.g. apixaban

Question 10

which drugs can be used to treat asthma during pregnancy?

Answer 10

• Risk of medication use are lower than risk of untreated asthama
• B2 agonist- albuterol, salbutamol - safe
• Inhaled corticosteroid- budesonide
• Theophyline- potential toxicity
• Systemic corticosteroid- severe asthama

Question 11

which drugs can be used during pregnancy to treat headaches and migraines?

Answer 11

• paracetamol
• ibuprofen (avoid in 3rd trimester)
• sumatriptan for acute treatment of migraine
• propanolol lowest effective dose

Question 12

which antidepressants & antipsychotics can be used during pregnancy? which cannot?

Answer 12

• SSRI, where the benefits outweight potential risks
• teratogenic: lithium, diazepam, quetiapine

Question 13

which antibiotics can be used during pregnancy?

Answer 13

• penicillin
• macrolide e.g. azithromycin/erythromycin - use only if no alternative
• cephalosporins are generally safe

Question 14

which antibiotics are teratogenic?

Answer 14

• Tetracycline- do not prescribe, animal studies- effects on skeletal development, discolouration of teeth
• Sulphonamides- teratogenic-avoid in first trimester- folate antagonist
• Aminoglycosides- auditory or vestibular nerve damage -The risk is greatest with streptomycin.