Aerosolized pentamidine prophylaxis for PCP has been recommended in immunosuppressed children who cannot tolerate trimethoprim-sulfamethoxazole. During 6 months of prophylaxis, plasma was obtained at "peak" (end of inhalation), .5 hr following the completion of inhalation, and at "trough." The age, height and weight (mean +/- SD; minimum and maximum) were 7.3 +/- 2.9, 2.8, and 11 yrs.; 118 +/- 22.7, 77.5, and 141 cm; and 21.4 7.3, 10.9, and 28.9 kg. 300 mg of aerosolized pentamidine range 12.9 to 27.5 mg/kg) was administered via Respirgard II nebulizer in 6 of the patients; a fitted mask was used in the 7th. The trough concentrations were zero in all patients except one who had previously received intravenous pentamidine. On a weight basis, the dose was 3-6 times that used in adults. However, the peak plasma concentration, 3.9 +/- 6.8 ng/ml (mean SD; n = 34), did not differ (p > .05) from that observed in our adult historical controls (5.2 +/- 6.3 ng/ml; n = 291), and accumulation did not occur. Whether this unexpectedly low systemic absorption is due to differences in the mechanics of the inhalation or other factors is unknown. We conclude that the systemic toxicity of aerosolized pentamidine in children is likely to be low, as it is in adults.

*Pentamidine/PHARMACOKINETICS *Pneumonia, Pneumocystis carinii/PREVENTION & CONTROL

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