Drug monitoring

Question 1

Digoxin toxicity

Answer 1

Confusion, nausea, visual halos (yellow discolouration), arrhythmias

Question 2

Lithium toxicity

Answer 2

Early - tremor, tiredness

Late - arrhtymias, seizures, coma, renal failure, diabetes insipidus

Question 3

Phenytoin

Answer 3

Gum hypertrophy, ataxia, nystagmus, peripheral neuropathy

Question 4

Gentamicin (and vancomycin)

Answer 4

Ototoxicity

Nephrotoxicity

Question 5

Gentamicin monitoring

Answer 5

Usually 5-7 mg/kg OD, if severe renal failure or endocarditis may receive divided daily dosing
Measure gentamicin level 6-14h after last dose then use normogram to calculate when next dose should be given
In divided daily dosing should monitor peaks and troughs

Question 6

Paracetamol normogram

Answer 6

Measure plasma paracetamol levels at least 4h after ingestion - if above line on normogram should give NAC
If staggered overdose, treat with NAC

Question 7

INR targets

Answer 7

Usually 2.5 = 2-3

Metal heart replacement valves or recurrent VTE = 3.5

Question 8

Major bleeding whilst on warfarin

Answer 8

Stop warfarin
Give 5-10 mg IV vitamin K
Give prothrombin complex e.g. Beriplex

Question 9

INR > 8

Answer 9

Hold warfarin
Minor bleeding = IV vitamin K
No bleeding = Give 1-5 mg oral vitamin K

Question 10

INR 5-8

Answer 10

Hold warfarin
Minor bleeding = IV Vit K
No bleeding = withhold 1-2 doses and reduce subsequent maintenance dose

Question 11

Re-starting warfarin

Answer 11

Review INR after 24 hours, may need more vitamin K

Restart when INR < 5

Question 12

Peri- op warfarin

Answer 12

Stop 5d before elective surgery
Give oral Vit K the day before surgery if INR > 1.5
If high risk of VTE - can bridge with LMWH but should stop 24 h before surgery

Question 13

Ciclosporin

Answer 13

Serum creatinine

BP