Influence of fulvic acid and hydroxy propyl-β-cyclodextrin on aspirin degradation

Abstract

Objective: The degradation of aspirin (ASA) was investigated to reveal information about the influence of complexation with fulvic acid (FA), as a new complexing agent and compared with hydroxy propyl-β-cyclodextrin complex. Materials and methods: ASA was complexed with FA in the molar ratio 1:0.5, 1:1, and 1:2 by different methods through lyophilization, solvent evaporation, and spray drying. Spray-dried (1:1) ASA–hydroxy propyl-β-cyclodextrin complex was prepared and compared with optimized complex of FA. All the complexes and ASA alone were packaged in well-labeled sealed polythene-lined aluminum pouches and stored in stability chamber at 40 ± 2°C and 75 ± 5% relative humidity for 120 days. Samples were analyzed for salicylic acid content at 0, 30, 60, 90, and 120 days. Results: Overall 4.31% salicylic acid was formed in 1:1 ASA–FA spray-dried complex, which was optimized stable complex among other complexes of FA prepared by different methods in different molar ratios. However, 2.35% salicylic acid was measured with 1:1 spray-dried ASA–hydroxy propyl-β-cyclodextrin complex. Stability of ASA increased more when complexed with hydroxy propyl-β-cyclodextrin as compared to FA. Conclusions: A novel complexing agent in the form of FA was investigated to increase the stability of ASA. A marked improvement in stability of ASA was observed when complexed with hydroxy propyl-β-cyclodextrin (1:1) by spray drying as compared to 1:1 spray-dried ASA–FA complex.