Pharmacology

Question 1

Which medications are known to cause gingival hyperplasia (ie overgrowth of the gums)?

Answer 1

Phenytoin
Calcium channel blockers e.g nifedipine
Ciclosporin

Question 2

Which are the most common medications to cause hyponatraemia?

Answer 2

• Diuretics of any type but especially thiazide diuretics
• SSRIs - worse culprit of which is Citalopram - are the antidepressant category most associated with hyponatraemia
• Antipsychotics - can cause multiple electrolyte abnormalities including low Na e.g haloperidol, phenothiazine
• Carbamazepine

Question 3

what medications commonly cause low B12?

Answer 3

metformin
COCP
PPIs
Histamine antagonists

Question 4

What do BNF guidelines suggest to do with elevated INR in patients on warfarin?

Answer 4

INR 5-8 - no bleeding - withhold 1-2 doses of warfarin and then restart warfarin at lower maintenance dose.

INR 5-8 w/ minor bleeding - stop warfarin, give slow IV injection of phytomenadione (Vit K1) and don’t restart warfarin until INR < 5.

INR > 8 with no bleeding - stop warfarin, give phytomenadione orally (off-license), repeat the vit K after 24 hrs if INR still high after 24 hrs. Restart warfarin once INR <5.

INR >8 with minor bleeding - stop warfarin, give IV phytomenadione, repeat after 24 hrs if INR still too high. Restart warfarin once INR < 5.

If major bleeding = stop warfarin, give IV phytomenadione, give dried prothrombin complex (or FFP if not available, but less effective)