Abstract
Solid dispersion has shown to be a promising formulation strategy to enhance dissolution for hydrophobic drugs. However, solid dispersions are often thermodynamically unstable, there is a continuous interest in studying their stabilities. In this study, attenuated total reflectance Fourier transform infrared (ATR-FTIR) was used to compare the amount of crystalline nifedipine formed in different formula of poly(ethylene glycol) (PEG)–nifedipine solid dispersions when exposed at various relative humidities (RHs) for 2 h at 40◦C. The ratio of the crystalline nifedipine band and an internal reference band in the out of plane (C–H) region has been used to indicate the relative degree of drug crystallisation in a sample. A band ratio of ∼0.05 and 0.5 was respectively indicative of a fully amorphous or crystallised drug in the formula. Results show that increasing the RH generally increases the amount of crystalline nifedipine. Formulations with low (5%, w/w) nifedipine concentration in higher molecular weight PEG were found to be better at resisting crystallisation. Deliquescence of the 10% nifedipine in PEG 4000 was observed at 77% and 100% RH with a reduction in crystalline nifedipine. All 5% (w/w) nifedipine samples were stable at RH below 77%. Crystallisation of nifedipine occurred at all RH when drug loading was increased to 10% (w/w).
| Original language | English |
|---|---|
| Pages (from-to) | 280-284 |
| Number of pages | 5 |
| Journal | Journal of Pharmaceutical Sciences |
| Volume | 104 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Jan 2015 |