Drug monitoring Flashcards
How do we calculate gentamicin doses for patients?
According to renal function and patient’s weight
Most patients are treated with a high dose regimen of 5-7mg/kg once daily
However, patients with severe renal failure (Creatinine clearence <20ml/min) or endocarditis may recieve a divided daily dosing (1mg/kg) 12- hourly (in renal failure) or 8-hourly (in endocarditis) - see BNF for divided daily dosing
How do we treat paracetamol overdose?
Management involves:
- Specific managment: N-acetyl cysteine (NAC)) if appropriate
- Supportive management (IV fluids)
Nomogram - in BNF - treatment summary > poisoning emergency treatment
- Used after 4 hrs of ingestion, give NAC to anyone with concentration levels above treatment line or if ingestion time is unknown
How do we monitor warfarin?
What is the normal INR and target INR?
Warfarin inhibits synthesis of vitamin-K dependent clotting factors (II, VII, IX and X) - prolonging prothrombin time (PT) where the INR is derived
Normal INR = 1
Target INR for patients on warfarin - 2.5
If recent thromboembolic event or metallic heart vale, target - 3.5
What happens if there is a major bleed on warfarin?
How do we manage over anticoagulation?
- Stop warfarin
- Give 5-10mg IV vitamin K
- Give prothrombin complex (Beriplex)
- INR<6 and no bleed: Reduce warfarin dose
- INR <6 with minor bleed: give IV vitamin K 1-3mg
- INR 6-8: Omit warfarin for 2 days then reduce dose
- INR>8: omit warfarin and give 1-5mg oral vitamin K
What are the common features of toxicity of the following?
- Digoxin
- Lithium
- Phenytoin
- Gentamicin
- Vancomycin
- Confusion, nausea, visual halos and arrhythmias
- Early: Tremor, Immediate: Tiredness, Late: Arrhythmias, seizures, coma, renal failure and diabetes insipidus
- Gum hypertrophy, ataxia, nystagmus, peripheral neuropathy and teratogenicity
- Ototoxicity and nephrotoxicity
- Ototoxicity and nephrotoxicity
