Drugs Flashcards
Does LMWH require monitoring?
No
Does UH require monitoring?
Yes - APPT
Impact of quinolones on seizure threshold?
Lowers seizure threshold
Which CCB is the most highly negatively inotropic?
Verapamil
Mx of ethylene glycol toxicity (i.e. anti-freeze)?
Fomepizole
Mx of heparin-induced thrombocytopenia?
Anticoagulation can be provided by direct thrombin inhibitor e.g. argatroban
Mechanism of allopurinol?
Xanthine oxidase inhibitor
Why should allopurinol and azathioprine never be prescribed together?
Azathioprine is a prodrug, meaning it is metabolised to its active form, 6-mercaptopurine, which causes immunosuppression (prevents kidney rejection in this patient). The active 6-mercaptopurine is subsequently metabolised by xanthine oxidase to inactive uric acid which is excreted.
As allopurinol inhibits xanthine oxidase, the combination of the two drugs can lead to excessive myelosuppression and therefore increase the risk of neutropenic sepsis.
Name some drugs that can cause lung fibrosis
- amiodarone
- bleomycin
- nitrofurantoin
- ergot-derived bromine agonists e.g. bromocriptine, cabergoline
- methotrexate
- sulfalazine
Mx of organophosphate poisoning (e.g. insecticides)?
Atropine
Organophosphate poisoning causes inhibition of acetylcholinesterase –> bradycardia.
Mechanism of UH?
Activates antithrombin III
This then inhibits Xa, Ixa, Xia and XIIa
Mechanism of flecainide?
Sodium channel blocker
What is the most appropriate interval to leave before increasing the dose of metformin?
1 week
Mx of adrenaline induced ischaemia?
Phentolamine
What is the most appropriate way to assess the patient’s response to dalteparin (LMWH)?
Monitor anti-factor Xa levels.
This is because LMWH exerts its anticoagulant effect mainly by inhibiting Factor Xa.
What may be one of the earliest symptoms of aspirin overdose?
Tinnitus
Can cocaine increase the risk of serotonin syndrome?
No
When is IV magnesium sulphate indicated?
Mg <0.4 mmol/L
or tetany, arrhythmias or seizures
How can nifedipine cause tachycardia?
Nifedipine causes peripheral vasodilation which may result in reflex tachycardia
Effect of P450 enzyme inducers and inhibitors in paracetamol overdose?
The trick here is that the metabolite of paracetamol (NAPQI) is toxic, rather than paracetamol itself.
Therefore, if a drug inhibits P450 enzymes, it is PROTECTIVE in the case of paracetamol, as it prevents the enzymes from metabolising even more toxic NAPQI.
How can digoxin affect appetite?
Can cause anorexia
How does digoxin affect K+ levels?
Digoxin can cause HYPERkalaemia.
HYPOkalaemia can predispose to digoxin toxicity.
Mx of digoxin OD?
Digibind (specific antibodies)
What class of drug (as well as anticholinergics) can cause urinary retention?
Opioids e.g. codeine, tramadol, morphine
Which TB drug can cause gout?
Pyrazinamide
Mechanism of dobutamine (e.g. in cardiogenic shock)?
Beta-1 agonist
Mechanism of depolarising muscle relaxants?
Nicotinic agonists
How long after taking phenytoin should you measure levels?
Immediately before next dose
What does the black triangle sign mean in the BNF?
Newly licensed drugs
What does PoM mean in the bnf?
Prescription only medicine
1st line for motion sickness?
1) Hyoscine
2) Cyclizine
3) Promethazine
How does St Johns Wort affect P450 system?
Inducer
Effect of amiodarone on P450?
Inhibitor
