Characterization of Solid Nifedipine-hydroxypropylmethylcellulose Films Using Visible Spectrophotometry Technique

Conventional matrix characterization by visible spectrophotometry technique required sample destruction and limited to drug content assay. This study investigated the capacity of visible spectrophotometry technique to characterize both drug content and molecular characteristics of solid nifedipine-hydroxypropylmethylcellulose films stored at 25 and 50 % relative humidities in their intact form. A significant correlation between film drug load and visible wave absorption intensity was attainable (r ≥ 0.983, p < 0.01). The visible wave absorption intensity of nifedipine in film varied with storage humidity with a rise in absorption intensity at 755nm following an increase in matrix interaction via C=C and/or C=O, and at 545, 585 and 638 nm via N-H, O-H and/or C-H moieties. Changes in polymeric domain affected the microenvironment of drug and were reflected by visible wave absorption profile of matrix. Visible spectrophotometry technique can be used to characterize drug content and as alternative detector for molecular changes of solid films.