This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Propronolol is useful in all except - 
Select and explain. 
A. Atrial flutter, B. Parkinsonian tremor, C. Thyrotoxicosis, D. HOCM
B: Parkinsonian tremor
Answer: B: Parkinsonian tremor 
Explanation: Ans. is 'b' i.e., Parkinsonian tremor o Propranolol inhibits the tremors which are due to overactivity of adrenergic system b 2-receptor), e.g. in thyrotoxicosis. o But, parkinsonian tremor and intention tremor are not due to sympathetic overactivity --> b -blocker has no role. b -blockers are DOC for HOCM and for controling the ventricular rate in atrial fibrillation.