Pharmacology Flashcards
Name some tocolytics
'It's Not My Time' Indomethecin (NSAID) Nifedipine (Ca2+ channel blocker) MgSO4 Terbutaline (beta-blocker) Atosiban (oxytocin antagonist)
What drugs cross the placenta?
Assume all do
Unless high molecular weight (insulin, heparin)
What drug doses need to change in pregnancy?
If they have a narrow therapeutic window, due to the change in volume of distribution. Monitoring of phenytoin, carbamazepine and digoxin is therefore recommended
Define teratogen
An agent that cause or contribute to a malformation, or abnormal physiological function or affect neurological development of the exposed fetus during pregnancy or following birth.
Dose dependent
What is the worst time for teratogenicity?
The most vulnerable time is the 1st trimester (first 17 days will lead to miscarriage or replacement of cells and a normal pregnancy)
Give 7 common examples of teratogenic drugs
- ACEi and Ang-II antagonists (lung and kidney hypoplasia, hypocalvaria)
- Antiepileptics (neural tube, cardiac, facial and limb defect, mental retardation)
- Cytotoxic agents (miscarriage)
- Sex hormones progesterone and oestrogen (virilisation of female, feminisation of male)
- Lithium (cardio defects, congenital goitre, prematurity, fetal macrosomia, floppy infant syndromes)
- Thalidomide (limb defects, central facial naevus, cleft palate, CV, neuro development, GI and urogenital problems)
- Warfarin (nasal hypoplasia, chondrodysplasia punctata)
What pharmacokinetics change in pregnancy?
Decreased GI motility, plasma protein
Increased lung function, skin blood circulation, plasma volume, body water, liver activity and GFR
Risks of antiepileptics in pregnancy
- Up to 10% risk of an abnormal baby
- Heart defects, cleft palate, neural tube and GU malformations
- Dose related
How is risk of antiepileptics in pregnancy reduced?
Avoid them for neuropathic pain and mood
Epilepsy: take lowest dose possible
Take folic acid 5mg for first 12 weeks
Carbamazepine is safest
How is diabetes treated differently in pregnancy?
- Oral hypoglycaemic agents should be stopped in pregnancy, apart from metformin
- Insulin should be started instead, if required
- Statins should be stopped in pregnancy
How is hypertension treated differently in pregnancy?
- NO ACEi or Ang-II antagonists
- Labetalol is 1st line (unless asthmatic)
- Nifedipine and methyldopa are alternatives
What are NSAIDs used for in O and G?
Pain relief
Menorrhagia (antiprostaglandin & pain relief)
Tocolysis (antiprost, reduced contractility of uterus)
Name an antifibrinolytic and action
SE?
Tranexamic acid
Inhibits plasminogen-> plasmin
SE: thrombosis
What is atosiban? SE
Oxytocin receptor antagonist
Tocolytic
Headache
SE of indomethacin
NSAID used in tocolysis
Blocks prostaglandin production
Headaches
May close ductus arteriosus prematurely and cause reduced renal function and oligohydramnios
Name 2 GnRH agonists, also called?
Gonadorelin analogues
Goserelin
Triptorelin
What are GnRH agonists used for? 4 uses
In menorrhagia due to fibroids
-> correct anaemia due to reversible menopause
Used before fibroid surgery
-> deceases size of fibroids and reduces surgical blood loss
Endometriosis
Precocious puberty
Action of GnRH agonists
Suppress hypo-pituitary-ovarian axis
Causes reversible menopause
Used for 3-6 months at a time
What is danazol? SE?
testosterone derivative
Causes hypo-oestrogen and hypoprogesterone state (pseudomenopause)
SE: deep voice
What is danazol used for?
Endometriosis
Causes endometrial regression and atrophy
What is oxybutynin?
Antimuscarinic
Used in detrusor overactivity (in urinary incontinence)
How does oxybutynin work?
Delays initial drive to void
Decreases detrusor strength
Decreases frequency of detrusor contractions
SE of oxybutynin
Anticholinergic: dry mouth constipation blurred vision drowsiness
What is solifenacin?
Antimuscarinic used for urge incontinence
