<prompt> A person with violent behavior and agitation was dia-gnosed to have Schizophrenia and was receiving haloperi!dol. Following this he developed rigidity and inability to move his eyes. Which of the following drugs should be added to his treatment intravenously for this condition?DiazepamResperidonePromethazineHaloperidol  <response>: Ans: C. PromethazineRef: Harrison I9e p2624, 18e p3544; Katzung I 3e p500-501, I2e p495.This case suggestive of acate muscular dystonia in schizophrenia patient.Due to rigidity inabilily to move eyes after haloperidol use.Treatment:IM anticholinergic benztropine.IVIM antihistaminic diphenhydramine hydrochloride - Relieves symptoms.Promethazine 25-50 mg IV or IM - used less frequently but readily available.Acute Muscular Dystonia:Features:Bizarre muscle spasms, mostly involving linguo-facial muscles-grinacing, toicollis, locked jaw.Occurs within few hours of single dose or at most in first week of therapy.More common in children below 10 years in girls, paicularly after parenteral administration.Treatment:Central anticholinergic, promethazineo or hydroryzine. 