system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Patient undergoing surgery was given a muscle relaxant. It produced marked fall in B.P. and increase in airway resistance which were reversed with diphenhydramine. The muscle relaxant was most probably:
assistant
The correct answer is  Hypotension and bronchoconstriction (increase in airway resistance) are impoant adverse effects caused by histamine. This is confirmed to be due to histamine because of reversal with diphenhydramine. * Maximum histamine release is caused by d-tubocurarine. * Vecuronium does not cause histamine release, therefore is preferred agent in asthmatic patients.