Prescription review Flashcards
When to stop COCP and HRT before surgery?
4 weeks (due to risk of thromboembolism)
When to stop ACEi/ARBs before surgery?
24hrs (due to profound hypotension if used with general anaesthetic)
When to stop lithium before surgery?
24hrs before MAJOR surgery (can be continued in minor ops)
When to stop K-sparing diuretics like spironolactone before surgery?
On MORNING of surgery (as it can cause hyperkalaemia if renal perfusion drops during surgery)
When should warfarin be stopped pre-op?
- What should be prescribed in interim?
5 days.
LMWH should be prescribed in interim
How many days pre-op should you stop DOACs (e.g. apixaban)?
48hrs
Is aspirin stopped pre-op?
Up to 1 week before (as with all anti-platelets)
When to stop insulin pre-op?
Avoid morning dose
When to stop oral hypoglycaemics pre-op?
Avoid on day of operation
When to stop metformin?
Avoid for 2 days after surgery due to risk of lactic acidosi
Steroid rules peri-operatively
- If NBM, convert oral steroids to IV
2. Increase dose of steroids pre-op
Hyperkalaemia causes
SHANT o Spironolactone o Heparin o ACEi/ARB o NSAIDs o Tacrolimus
Hyponatraemia causes
SAD
o SSRIs
o Anticonvulsants
o Diuretics
Hyperglycaemia?
CAT-B o Corticosteroids o Atypical antipsychotics (olanzapine, risperidone) o Thiazide diuretics & Tacrolimus o BBs
Hypoglycaemia?
The diabetic drugs, EXCEPT metformin! Metformin DOES NOT cause hypoglycaemia – don’t let them trick you.
Which drugs have doses in mcg?
Digoxin and levothyroxine (watch out in dosing error Qs)
Which drugs are given weekly?
Methotrexate and alendronic acid
If you see a drug given in grams, double check it’s correct
This is because it’s relatively rare and could come up in a drug dosing error Q
Why might some anticoagulants/antiplatelets be switched to a heparin peri-operatively?
as it’s much easier to reverse (via protamine sulphate)
Drugs causing confusion (and thus falls)
- Drugs with anti-cholinergic effects (e.g. antidepressants)
- Z drugs (e.g. zoplicone and benzodiazepine)
- Steroids (e.g. prednisolone)
- Anti-hypertensives (particularly diuretics –> postural drop)
Which drugs cause long Qtc?
- Anti-psychotics
- Anti-depressants
- Anti-emetics
- Beta blockers (e.g. sotalol)
- Potassium channel blockers (e.g. amiodarone)
- Sodium channel blockers (e.g. flecainide)
- Certain antibiotics (e.g. ciprofloxacin, erythromycin)
P450 enzyme inducers
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- Sodium valproate
- Isoniazid
- Cimetidine
- Ketoconazole
- Fluconazole
- Alcohol (binge)
- Chloramphenicol
- Erythromycin
- Sulphonamides
- Ciprofloaxacin
- Omeprazole
- Metronidazole
P450 enzyme inhibitors
SCRAP GPS
- St John’s Wart
- Carbamazepine
- Rifampicin
- Alcohol (chronic)
- Phenytoin
- Griseofulvin
- Phenobarbitone
- Sulphonylureas
When to stop metformin?
When eGFR <30.
Allopurinol can accumulate in renal dysfunction
BNF advises max daily dose of 100mg until renal function improves
In UTI questions, when should you avoid nitrofurantoin?
If eGFR <45. Use trimethoprim instead!
A small rise in creatinine (<20%) is to be expected when starting an ACEi
Thus does not require Ix or change in prescription
when else to stop metformin?
the day before surgery
