Estimation of available epinephrine dose in expired and discolored autoinjectors via quantitative smartphone imaging

• Published in: Analytical and bioanalytical chemistry 2020-05, Vol.412 (12), p.2785-2793
• Main Authors: Saleheen, Amirus, Campbell, Bill M., Prosser, Rebecca A., Baker, Christopher A.
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Anaphylaxis; Anaphylaxis - drug therapy; Biochemistry; Cameras; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Color; Colorimetry; Correlation; Diagnostic Imaging - methods; Discoloration; Drug Stability; Drug Storage - standards; Epinephrine; Epinephrine - administration & dosage; Epinephrine - analysis; First aid; First aid in illness and injury; Food Science; Humans; Image filters; Industry standards; Injections, Intramuscular; Laboratory Medicine; Medical equipment; Monitoring/Environmental Analysis; Patient compliance; Pharmaceutical industry; Research Paper; Self Administration - instrumentation; Self Administration - methods; Smart phones; Smartphone - instrumentation; Smartphones; Spectrophotometry; Storage conditions
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-020-02505-y

Epinephrine autoinjectors (EAIs) are important first aid medications for treating anaphylaxis. A 10-fold price increase over the past 12 years and evidence that expired EAIs may still contain significant doses of available epinephrine have motivated interest in the efficacy of expired EAIs as treatments of last resort. Degradation of expired EAIs, which can be caused by improper storage conditions, results in various degrees of discoloration of the epinephrine solution. Previous studies have determined that significant epinephrine remains available in expired EAIs, but these have only considered EAIs that show no discoloration. Here, we investigate the potential for colorimetric estimation of available epinephrine dose based on the degree of discoloration in expired EAIs. The correlation of available epinephrine dose and time since expiration date was poor ( r  = − 0.37), as determined by an industry standard UHPLC protocol. Visible absorbance of the samples integrated across the range 430–475 nm correlated well with available epinephrine dose ( r  = − 0.71). This wavelength corresponds to the blue channel of a typical smartphone camera Bayer filter. Smartphone camera images of the EAI solutions in various illumination conditions were analyzed to assign color indices representing the degree of discoloration. Color index of the samples showed similar correlation (| r | > 0.7) with available epinephrine dose as that of visible spectrophotometry. Smartphone imaging colorimetry is proposed as a potential point-of-use epinephrine dose estimator for expired and degraded EAIs. Graphical abstract