Drug Reactions

Question 1

ADRs

Answer 1

TCA: anti-muscarinic
BB: cold + brady + asthma
Spiro: gynae (same for cimetidine)
ABx: diarrhoea (AAD)
NSAIDs: asthma + GI
Digoxin: vom and visual
cytotoxics: BMF/myelosuppression
penicillins: anaphylaxis/rash
agranulocytosis and thrombocytopenia (idiosyncratic)

Question 2

Specific ADRs

Answer 2

NSAIDS and ulcers: PPx (misoprostol/PPI)
NSAIDS and CVD: fluid retention, HTN, CHF; use aspirin instead
NSAIDS and renal damage: reduce GFR, risk of AKI and AIN

BB and asthma: even selective; caution in COPD
Statins: myopathy risk; rhabdomyolysis and renal damage (Rare)
skin reaction: SJS, rash/urticaria, erythema; often delayed

Question 3

Interactions

Answer 3

Absorption e.g. tetra and heavy metals
pH e.g. antacids
binding e.g. colesystyramine
GI motility: e.g. metoclopramide (Reduce absorption time)
Metabolism (CYP, separate card)
Excretion: renal impairment, pH (opposite e.g. alkaline = more acid excreted), transporter competition (e.g. NSAIDs and MTX)
fluid and electrolytes: e.g. K with ACEI, spiro, diuretics, digoxin (hypo = toxicity)

Question 4

Metabolism

Answer 4

Inducers: delayed, increase metabolism; PC BRASSS
inhibitors: immediate, decrease metabolism; cimetidine, macrolide, quinolones, ciclosporin, antifungal, PPI

Question 5

key interactions

Answer 5

warfarin and NSAIDs: bleeds
warfarin and ABx: bleeds (erythro and cipro)
NSAIDs and MTX: toxicity
ACEI and K-sparing: hyperkalaemia
RL-CCB and BB: bradycardia/asystole
digoxin and amiodarone: toxicity
digoxin and verapamil: toxicity
OCP and enzyme inducers: failure e.g. rif, carba, pheny
alcohol: CNS depp, gastric, metronidazole

Question 6

key drugs

Answer 6

warfarin
lithium
digoxin
theophylline
enzyme inducers/inhibitors
herbals
anything affecting fluid/electrolyte balance