Acetylcholine in Paroxysmal Tachycardia

To the Editor:— In Queries and Minor Notes inThe Journal, June 10, page 2459, a question is answered regarding the use of acetylcholine in attacks of paroxysmal tachycardia. The answer to the question contains a grievous error in failing to distinguish between the highly unstable acetylcholine and the much more stable choline derivatives, such as mecholyl and doryl. One would suppose from reading the answer that acetylcholine would stop attacks of paroxysmal when given in doses of from 20 to 30 mg. subcutaneously and that it would cause flushing, salivation, sweating and possibly more serious effects in this dosage. This is completely erroneous. Acetylcholine given in this dosage subcutaneously causes practically no effects whatever, and there is no valid evidence that it has ever stopped an attack of paroxysmal tachycardia. Had the question read please inform me regarding the use of acetyl-β-methylcholine (mecholyl) in paroxysmal tachycardia the answer