Age dependent systemic exposure to inhaled salbutamol

AIMS: To determine the effect of age on systemic exposure to inhaled salbutamol in children.

METHODS: Fifty-eight asthmatic children, aged 3-16 years, inhaled 400 microg of salbutamol from a pressurized metered dose inhaler with spacer. The 20 min serum profile was analyzed.

RESULTS: Prescribing a dose on a microg kg(-1) basis caused reduced systemic exposure in young children (Y) compared with older children (O) (C(max-microg kg(-1)-adjusted) Y : O ratio (95%CI) = 0.55 (0.47, 0.65)) whereas a fixed nominal dose irrespective of age caused increased exposure in young children (C(max) Y : O ratio (95%CI) = 1.7 (1.3, 2.2)).

CONCLUSIONS: For similar systemic exposure, dosing should be adjusted to age or size but not on a fixed microg kg(-1) basis, which may lead to unnecessary suboptimal dosing.