Background: Analysis of drug concentrations in biological fluids is required in clinical
sciences for various purposes. Among other biological samples, exhaled breath condensate (EBC) is
a potential sample for follow up of drug concentrations.
Methods: A dispersive liquid-liquid microextraction (DLLME) procedure followed by a validated
liquid chromatography method was employed for the determination of budesonide (BDS) in EBC
samples collected using a homemade setup. EBC is a non-invasive biological sample with possible
applications for monitoring drug concentrations. The proposed analytical method is validated according
to the FDA guidelines using EBC-spiked samples. Its applicability is tested on EBC samples collected
from healthy volunteers receiving a single puff of BDS.
Results: The best DLLME conditions involved the use of methanol (1 mL) as a disperser solvent,
chloroform (200 μL) as an extraction solvent, and centrifugation rate of 3500 rpm for 5 minutes. The
method was validated over a concentration range of 21-210 μg·L-1 in EBC. Inter- and intra-day precisions
were less than 10% where the acceptable levels are less than 20%. The validated method was
successfully applied for the determination of BDS in EBC samples.
Conclusion: The findings of this study indicate that the developed method can be used for the extraction
and quantification of BDS in EBC samples using a low cost method.