Managing the Risks of Prescribing Flashcards
what is the definition for a adverse drug reaction
an adverse event where it is suspected to be caused by a drug
Type A (augmented) ADRs
- dose related
- common, predictable,
- related to the pharmacology
- unlikely to be fatal
Type B (bizarre) ADRs
- not dose related
- uncommon, unpredictable
- not related to the pharmacology
- often fatal
drug food interaction with ACEi
pts who have swapped their dietary salt for potassium containing salt e.g.LoSalt
what does grapefruit juice do
inhibit CYP3A4
aminoglycosides and loops diuretics
additive effect causing ototoxicity
pharmacodynamic reaction
lithium salts and ramipril
a reduction in the excretion of lithium can cause toxicity
pharmacokinetics reaction
rifampicin and COCP
pharmacokinetic reaction
rifampicin induces cytochrome P450 which can reduce the effectiveness of oestrogens and progestogens
Verapamil and BB
pharmacodynamic reaction
both are negative inotropes –> bradycardia, hypotension, asystole
warfarin and NSAIDs
pharmacodynamic
warfarin increases risk of GI haemorrhage
warfarin and macrolide abx: clarithromycin, erythromycin
pharmacokinetic
increases INR
needs emergency contraception and is on carbamazepine. What do u give?
1st line: copper coil
2nd line: double dose levonorgestrel because carbamazepine is a CP450 enzyme inducer
inducer of the CP450 system
rifampicin
St john’s wort
phenytoin, carbamazepine
inhibitors of CYP system
erythromycin
grapefruit juice
cranberry juice
how often should pts be monitored following a dose change of levothyroxine
6-8w
how often should pts be monitored who are prescribed a maintenance dose of levothyroxine
annually
what should be monitored when on amiodarone
TFT
what should be monitored when on digoxin
HR
what should be monitored when on gentamicin
plasma conc
what should be monitored when on methotrexate
FBC
possible drug causes of hypokalaemia
- laxatives
- prednisolone
- insulin
- loop diuretics
- salbutamol
- gentamicin, amphotericin
- Bendroflumethiazide
- theophylline
what is the max conc of potassium chloride via peripheral rout
40mmol/litre
which drugs can cause hyperkalaemia
- ACEi
- acute digoxin overdose
- angiotensin-II receptor blockers
- heparin + LMWH
- NSAIDs
- Penicillins
- K sparing diuretics
- trimethoprim
monitoring with gentamicin
plasma drug concentration is usually measured 18–24 hours
after the first dose (trough level).
The next dose should only be
administered if these have fallen to a safe level with a low risk of toxicity
(e.g. gentamicin <1 mg/mL).
If the plasma concentration is too high, the
next dose should be withheld until repeat levels indicate that it is safe to
give.
sx of gentamicin toxicity
- tinnitus/ deaf
- N+V
- renal dysfunction
- colitis
- stomatitis
- blood dyscrasias
vancomycin infusion administration
infuse over at least 60min
what is red man syndrome
caused by vancomycin if infused rapidly
vancomycin moniotring
measure levels after 36-72hr (3-6 doses)
patients with hyperthyroidism require higher or lower doses of warfarin
lower
true or false:
ibuprofen should be avoided in pts taking warfarin
true
true or false:
the anticoagulant effect of warfarin can be enhanced by fluconazole
true
true or false:
the anticoagulant effect of warfarin is increased by amiodarone
true
what drug antagonises warfarin
phytomenadione
when should yo measure plasma digoxin conc
when you suspect toxicity
if amiodarone therapy is added to digoxin therapy, what should you do to the dose of digoxin
halve it
sx of digoxin toxicity
similar signs to clinical deterioration
which drug shold yo be brand specific
lithium
lithium toxicity is excaberbated by the low conc of which electrolyte
sodium
which abx sholdn’t be prescribed with methotrexate
trimethoprim
