Effect of enzyme inducers
Increase activity of CYP450s, decreasing effect of drugs broken down by these
Effect of enzyme inhibitors
Decrease activity of CYP450s, increasing effect of drugs broken down by these
Interaction between warfarin and CYP inhibitor (e.g erythromycin)
Increase in INR due to raised warfarin levels - risk bleeding
Common inducers
PC BRAS Phenytoin Carbamazepine Barbiturates Rifampicin Alcohol (chronic excess) Sulphonureas
Common inhibitors
Ketoconazole, ciprofloxacin, erythromycin and grapefuit juice AO DEVICES Allopurinol Omeprazole Disulfiram Erythromycin Valproate Isoniazid Ciprofloxacin Ethanol (acute intox) Sulphonamides
Drugs to stop before surgery
I LACK OP Insulin Lithium Anticoags/platelets COCP/HRT K-sparing diuretics Oral hypoglycaemics Perindropril (and other ACE-inhibs)
Drugs to increase before surgery
Corticosteroids if adreno-supressed - IV steroids at induction of anaesthesia to support adequate stress response to surgery
What does taking metformin risk prior to surgery
Lactic acidosis as nill by mouth. Other oral-hypoglycaemics risk hypo
How long before op should COCP/HRT be stopped
4 weeks
How long before op should Lithium be stopped
Day before
How long before op should potassium-sparing diuretics be stopped
Day of op
Max daily dose of paracetemol
4g
PReSCRIBER
Patient details REaction (allerfies plus what happens) Signing chart Contraindication for each drug Route Iv fluids required? Thromboprophylaxis required? (anti)Emetics required? (pain)Relief required?
Side effects of steroids
STEROIDS mneumonic Stomach ulcers Thin skin Edema Right/left heart failure Osteoporosis Infection (inc. candida) Diabetes (common cause of hyperglycaemia, uncommonly progresses to diabetes) Syndome - cushing's
Contraindications to NSAIDs
NSAID mnemonic No urine (i.e AKI/renal failure) Systolic dysfunction (i.e heart failure) Asthma Indigestion (any cause) Dyscrasia (clotting abnormality)
Aspirin contraindications
Same as NSAIDs except not contra in renal/heart failure or asthma
Effect of beta blockers in asthmatics
Wheeze
Unique ACE-inh effects
Dry cough and angiooedema
Which antihypertensives cause bradycardia?
Beta blockers and rate limiting Ca2+ channel blockers
Side effects of calcium channel blockers
Hypotensive effects, peripheral oedema and flushing
Effect of beta blockers on heart failure (acute and chronic)?
Worsens acute and beneficial in chronic
Side effects of diuretics
Hypotensive effects and renal failure. Other specific effects depend on type. Spironolactone causes gynaecomastia (eplerenone reduces this), Loops cause gout
Which fluid should be used as replacement if patient has ascites?
Human albumin solution
What level of fluid loss is indicated by reduced UO? (no tachycardia)
500ml