COMPARATIVE ABSORPTION OF INHALED AND INTRAMUSCULARLY ADMINISTERED ATROPINE

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Abstract
The inhalation of atropine sulfate was investigated in a randomized, 4-period, rising-dose study. Atropine sulfate 2, 4, and 6 mg by inhalation, and atropine free base 1.67 mg (equivalent to 2.0 mg atropine sulfate) by intramuscular (IM) injection were given to 8 healthy, nonsmoking subjects. Serum atropine sulfate concentrations were monitored during an 8-h period by radioimmunoassay. Mean serum concentrations and area under the serum concentration-versus-time-curves (AUC) increased as the inhaled dose increased. Peak concentrations (mean .+-. SD) were 11.5 .+-. 3.4, 16.4 .+-. 6.2, and 18.0 .+-. 3.1 ng/ml for the 2, 4, and 6 mg doses, and 11.7 .+-. 2.5 ng/ml for the IM dose. The time to peak concentration for each dose was similar (mean, 0.8 to 1.9 h). The AUC ratio of the 2-mg inhaled and IM doses was 1.11 .+-. 0.41. The observed bronchodilating, anticholinergic, and other pharmacologic effects were seem after all dose concentrations and were typical of atropine. This study showed that inhalation is an efficient way to administer atropine sulfate for systemic use.