ORAL ANTIHISTAMINES REDUCE THE SIDE-EFFECTS FROM RAPID VANCOMYCIN INFUSION

Rapid infusion of vancomycin causes histamine-mediated side effects, h ypotension, and rash, known as ''red man syndrome.'' in this prospecti ve, randomized, double-blind, placebo-controlled study, we examined th e ability of oral antihistamines to attenuate three clinical end point s: rash, hypotension, and vancomycin discontinuation, and we compared these findings with those of a similar study using N antihistamines. P atients (ASA physical status I-m) who required vancomycin prophylaxis for elective arthroplasty received either oral antihistamines (diphenh ydramine less than or equal to 1 mg/kg and cimetidine less than or equ al to 4 mg/kg, n = 20) or placebo (n = 10) Ih before rapid vancomycin infusion (I g over 10 min). The vancomycin infusion was discontinued i f the mean arterial blood pressure decreased by greater than or equal to 20% or if itching was intolerable for the patient. Clinically signi ficant hypotension developed in no treated patients, compared with fiv e (50%) patients in the placebo group (P = 0.001). Rapid infusion was stopped for one treated patient (5%) and for five (50%) patients in th e placebo group (P = 0.004). Incidence (P = 0.011) and severity of ras h (P = 0.015) were also reduced in treated patients. Peak histamine le vels were increased but were similar for patients in both groups (mean +/- so, 1.9 +/- 2.5 vs 1.6 +/- 2.4 ng/mL; P = 0.75). Oral antihistami nes were as effective as IV antihistamines. Zn conclusion, oral H-1 an d H-2 antihistamine pretreatment is a practical, safe, and inexpensive option to attenuate histamine-mediated side effects associated with r apid vancomycin infusion. Implications: Clinicians often must administ er vancomycin faster than the l-h recommended time, which can cause '' red man syndrome'' trash, itching, hypotension). Our randomized, doubl e-blind, placebo-controlled study showed that oral H-1 and H-2 antihis tamine pretreatment significantly reduced the histamine-related side e ffects of rapid vancomycin infusion.