SYSTEMIC CONCENTRATIONS OF SALBUTAMOL AND HFA-134A AFTER INHALATION OF SALBUTAMOL SULFATE IN A CHLOROFLUOROCARBON-FREE SYSTEM

The objective of this study was to determine if salbutamol was absorbe d from a new salbutamol sulfate chlorofluorocarbon (CFC)-free metered- dose inhaler (MDI). Measurement of HFA-134a, the CFC-free propellant, was included to provide proof of delivery of this MDI. Eight healthy m en received two inhalations (90 mu g salbutamol base equivalents per i nhalation ex adapter) from the CFC-free inhaler (MDI A) in period 1 an d from a reference CFC inhaler (MDI V) in period 2. Eight postdose sam ples were collected for the determination of salbutamol serum levels o ver a 4-h period, Salbutamol levels were not quantifiable in most samp les, Four subjects given MDI A and two given MDI V had a few transient salbutamol levels, which occurred in the first hour after dosing, wit hin a narrow range of 1-2 ng/ml and close to the lower limit of detect ion (1 ng/ml). No pharmacokinetic analyses were possible. Blood sample s were also collected after MDI A for propellant quantitation. HFA-134 a levels were seen in all subjects, verifying absorption, We conclude that the transient salbutamol serum levels can be attributed to the tw o-inhalation dose and not to either propellant system.