Chapter 9: Adverse Drug Reactions Flashcards Preview

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Flashcards in Chapter 9: Adverse Drug Reactions Deck (14):
1

Type A and Type B drug reactions

→ Type A reaction = common, predictable + dose related.

→ Type B reaction = idiosyncratic, bizarre + unexpected, related to gene/host/environmental interactions.

2

Adverse drug reactions: ABx

Gentamicin + vancomycin = nephrotoxicity + ototoxicity.

Any antibiotic (commonly broad-spectrum e.g. cephalosporins or ciprofloxacin) = clostridium difficile colitis.

3

Adverse drug reactions: Antihypertensives

ACE-i e.g. lisinopril = hypotension, electrolyte abnormalities, acute kidney injury, dry cough.

B-blockers e.g. bisoprolol = hypotension, bradycardia, wheeze in asthmatics, worsens acute HF (but helps chronic HF).

CCBs e.g. diltiazem = hypotension, bradycardia, peripheral oedema, flushing.

Diuretics e.g. furosemide, benfroflumethiazide, spironolactone = hypotension, electrolyte abnormalities, acute kidney injury, subclass dependent effects.

4

Adverse drug reactions: Anticoagulants/antiplatelets

Heparin = haemorrhage (especially if renal failure or <50kg), heparin-induced thrombocytopenia.

Warfarin = haemorrhage (but initial pro-coagulant effect, takes ~days to become anticoagulant, prescribe with heparin until INR>2).

Aspirin = haemorrhage, peptic ulcers + gastritis, tinnitus in large doses.

5

Adverse drug reactions: antiarrhythmics

Digoxin = N&V&D, blurred vision, confusion + drowsy, xanthopsia (disturbed yellow including ‘halo’ vision).

NB: Low K+ augments digoxin effect. High levels limit its effect.

Amiodarone: pulmonary fibrosis, thyroid disease (both hyper/hypothyroidism), skin greying, corneal deposits.

6

Adverse drug reactions: Mood stabilizers

Lithium 

  • early-tremor
  • intermediate-tiredness 
  • late-arrhythmias, seizures, coma, renal failure, diabetes insipidus.

7

Adverse drug reactions: Antipsychotics

Haloperidol = dyskinesias e.g. acute dystonic reactions, drowsiness.

Clozapine = agranulocytosis = required intensive monitoring of FBC.

8

Adverse drug reactions: Corticosteroids

Dexamethasone + prednisolone = STEROIDS → stomach ulcers, thin skin, oedema, R + L HF, osteoporosis, infections, diabetes (hyperglycaemia more likely) + Cushing’s syndrome.

Fludrocortisone = HTN, Na+ & H2O retention.

9

Adverse drug reactions: NSAIDs

Ibuprofen = NSAID → no urine, systolic dysfunction (HF), asthma, indigestion (any cause), dyscrasia (clotting abnormality).

10

Adverse drug reactions: Statins

Simvastatin = myalgia, abdominal pain, +++ALT/AST (can be mild), rhabdomyolysis (can be just mildly increased CK though).

11

Clinically important drug interactions.

Spot drugs on list known to interact – generally 1 of 3 categories.

What are these categories?

1) Drugs with narrow therapeutic index e.g. warfarin, digoxin + phenytoin.

2) Drugs requiring careful titration of dose according to effect e.g. antihypertensives, antidiabetic drugs. drugs where an overtreatment may result in harm. e.g. , iodinated contrast media causing renal impairment risking metformin-induced lactic acidosis (note low GCS or acidotic behaviour) or ACE-i AKI.

3) Drugs affecting (or affected by) CP450 enzymes = inducers PCBRAS; inhibitors = AODEVICES + ketoconazole + grapefruit juice.

12

Enzyme inducer = increase P450 enzyme activity = reduced levels of other drugs.

name some inducers

PC BRAS = phenytoin, carbamazepine, barbiturates, rifampicin, alcohol (chronic excess), sulphonylureas

13

Enzyme inhibitor = reduce P450 enzyme activity = increased levels of other drugs.

Name some inducers

AO DEVICES = allopurinol, omeprazole, disulfiram, erythromycin, valproate, isoniazid, ciprofloxacin, ethanol (acute intoxication), sulphonamides.

 

+KETOCONAZOLE 

+Grape fruit juice!

14

Drugs with potent interactions with ETOH

Alcohol can cause:

GI bleeding with NSAIDs.

Lactic acidosis with metformin.

Hypertensive crisis by MAO-i.

→ Increased anticoagulation with warfarin (acute alcohol – chronic alcohol reduces warfarin effect).

Sweating, flushing, N&V - metronidazole + disulfiram.

Sedation by barbiturates, opioids + benzodiazepines.