There are a few drugs that are commonly asked in MRCP Part 1 exams, these drugs include pheytoin, digoxin, warfarin, isoniazid,,aspirin etc. Today, I am going to discuss more about warfarin. You may be wandering why the above-mentioned drugs are being asked repeatedly in MRCP. The reason is simple because you would see a lot of patients on these drugs in clinical practice.
Warfarin is an anticoagulant. It inhibit the production of Vitamin K dependent coagulation factors namely II, VII, IX and X( a very popular question in Part 1). Warfarin causes prolongation of PT time ( or INR ) and groups of patients on warfarin include,
a) Patients with previous prosthetic valve replacement,
b) Patients with history of thromboembolic events such as pulmonary embolism, DVT and ventricular clot.
c) Patients with very high risk of developing embolic event such as in atrial fibrillation.
Common question in MRCP is warfarin drug interaction. There are numerous examples of drug interaction for warfarin.
However,remember the following,
a) Drugs that increase the effect of warfarin.....
- drugs which are liver enzyme inhibitors such as omeprazole, disulfiram, erthyromycin, valproate, isoniazid, cimetidine, metahnol(acute),sulphonamides (ODEVICES)
-drugs that cause displacement of warfarin from protein such as NSAID, OHA, metronidazole, salicylates, cotrimoxazole
b) Drugs that reduce the effect of warfarin......
- drugs which are liver enzyme inducers such as pheytoin, carbamazepine, barbiturates, rifampicin, alcohol (chronic) and sulphonyureas. (PCBRAS)
Questions about anticoagulation in MRCP:
1)Which ONE of the following is a contraindication to thrombolysis?
1 ) age over 75 years 2 ) the presence of atrial fibrillation
3 ) asthma 4 ) pregnancy 5 ) background diabetic retinopathy
ANSWER: 4
2)A patient presenting with atrial fibrillation who has reverted to sinus rhythm is more likely to remain in sinus rhythm in the following circumstances:
A age >75 years old B been commenced on warfarin C left atrium size > 6 cm on ECHO
D short history on AF E a ventricular rate on presentation of 130 bpm
ANSWER: D
3)A 70-year-old woman has a history of dyspnoea and palpitations for six months. An ECG at that time showed atrial fibrillation. She was given digoxin, diuretics and aspirin. She now presents with two short-lived episodes of altered sensation in the left face, left arm and leg. There is poor coordination of the left hand. ECHO was normal as was a CT head scan.
What is the most appropriate next step in management?
1 ) anticoagulation 2 ) carotid endarterectomy 3 ) clopidogrel 4 ) corticosteroid treatment 5 ) no action
ANSWER: 1
4)A 62 year old male undergoes cardioversion for idiopathic atrial fibrillation. Post-procedure he was shown to be in sinus rhythm. Medication at admission included Warfarin digoxin and atenololwhich he had been taking for the last six weeks.
Which of the following agents should he continue to take until he is seen in clinic in six weeks time.
1 ) Aspirin 2 ) Atenolol 3 ) Digoxin 4 ) Sotalol 5 ) Warfarin
ANSWER: 5
5)An 80 year-old male presented with palpitations of 5 hours duration. One month previously he suffered weakness of the right arm and problems with his speech which resolved within 4 hours. He was taking no medication. On examination, he was stable with a pulse of 135 beats per minute which was confirmed to be atrial fibrillation on ECG. He had a blood pressure of 112/80 mmHg, appeared clinically euthyroid. Within one hour he reverted to sinus rhythm spontaneously. Echocardiogram was normal but a 24 hour ECG revealed three episodes of atrial fibrillation each lasting around ten minutes.
Which one of the following is the most appropriate initial treatment for this patient?
1 ) Amiodarone 2 ) Aspirin 3 ) atenolol 4 ) digoxin 5 ) warfarin
ANSWER: 5
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