Age dependent systemic exposure to inhaled salbutamol

What is already known about this subject • There is only scant evidence on how to adjust the dose of inhaled drugs in children. • Salbutamol delivered via a pressurized metered dose inhaler (pMDI) with spacer is one of the most commonly used anti‐asthmatic treatments in children but the effect of age on systemic exposure following this treatment has not previously been investigated. What this study adds • The present study shows that prescribing salbutamol from a pMDI with spacer as a fixed dose kg−1 causes reduced exposure in young children with a corresponding risk of unnecessary suboptimal dosing. • On the other hand a fixed absolute dose causes some over‐dosing in young children. • The study underlines that research into the dosage regimens of aerosol treatment for children is needed to assure evidence based optimal treatment. 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 µg of salbutamol from a pressurized metered dose inhaler with spacer. The 20 min serum profile was analyzed. Results Prescribing a dose on a µg kg−1 basis caused reduced systemic exposure in young children (Y) compared with older children (O) ( 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 (Cmax 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 µg kg−1 basis, which may lead to unnecessary suboptimal dosing.