OBJECTIVE: To study the toleration of various infusate concentrations
of single intravenous doses of azithromycin. DESIGN: Randomized, doubl
e-blind, two-treatment, two-period, crossover. SETTING: Clinical pharm
acology unit. PARTICIPANTS: Twenty-four healthy men aged 19-41 years.
STUDY DESIGN: All subjects were initially randomized to receive single
1-hour intravenous infusions of azithromycin 1 g at infusate concentr
ations of 1, 2, or 5 mg/mL (n = 6 each) compared with placebo (n = 6).
Subjects who were randomized to receive 1 mg/mL concentrations were s
ubsequently administered 5 mg/mL concentrations at least 2 weeks later
, those given 2 mg/mL were crossed over to 4 mg/mL, and those in the 5
-mg/mL group were crossed over to 1 mg/mL concentrations. MAIN OUTCOME
MEASURES: Subjects recorded intravenous infusion toleration using vis
ual analog scales ranging from 0 (no signs or symptoms) to 10 (poor to
leration) for erythema, pain, swelling, and tenderness. Vascular Doppl
er recordings were obtained during and after infusion cephalad to the
infusion site. RESULTS: Infusion site reactions increased in incidence
and severity with infusion concentrations of 4 and 5 mg/mL; the most
frequent reactions were tenderness and erythema. There were no apparen
t trends in Doppler readings. CONCLUSIONS: Single doses of azithromyci
n 1 g at infusate concentrations up to 2 mg/mL were well tolerated whe
n administered over 1 hour to healthy men.