Introduction

Although adherence to inhaled medication is critical to treatment efficiency, ?50% do not adhere to their treatment (even in patients with severe asthma) or make critical errors in using the devices. Hair analysis could be a tool for therapeutic monitoring as hair concentrations reflect chronic exposure, which can be assessed from month to month using segmental analysis.

Aims and objectives

To provide proof-of-concept for monitoring inhaled drug exposure in asthma patients by measuring drugs in hair.

Methods

Prospective, open, interventional study in a university hospital (CorticHair, NCT03691961, Foch Hospital, France). Adult patients with controlled severe asthma receiving budesonide/formoterol were enrolled. Asthma control, lung function and adherence were recorded. Hair samples were taken after 4 months and cut in four 1 cm-segments from the root.

Results

Hair samples were available for 21/22 patients (20 women; median age 53 years; 600 [200-1600] µg/d budesonide (median [min-max])). Budesonide and formoterol were detected in samples from 18 and 13 patients, respectively. The concentrations were 6.4 [0.8-51.4] pg/mg for budesonide and 0.8 [0.1-13.1] pg/mg for formoterol. Budesonide concentration correlated with prescribed (r = 0.27, p = 0.024) and self-reported (r = 0.33, p = 0.006) inhaled doses but not formoterol. The coefficient of variation between the 4 hair segments was 21% [4-45] for budesonide and 38% [12-64] for formoterol.

Conclusions

These results confirm the feasibility of measuring budesonide and formoterol in the hair and suggest a relationship between drug exposure and hair concentrations. This may be of interest in difficult-to-treat severe asthma.