A. Chauvet et al., THERMAL-ANALYSIS AND DISSOLUTION AVAILABI LITY OF SOLID DISPERSIONS OF TOLBUTAMIDE, Journal of thermal analysis, 41(6), 1994, pp. 1253-1261
We have established the phase diagram tolbutamide (TBM)-PEG 6000 and d
etermined the eutectic composition 1/9 (w/w) in tolbutamide and meltin
g temperature 56.2-degrees-C+/-0.3; no solid solution has been found.
Negative mixing enthalpies of physical mixture (-2.5 J.g-1) and solid
dispersions coprecipitate (-3.9 J.g-1) melt (-9.9 J.g-1) for eutectic
composition involve the existence of interactions between drug and car
rier. We have determined the dissolution kinetics: amount % dissolved
(10 min) 65.87+/-0.55 (physical mixture), 78.02+/-0.02 (coprecipitate)
, 99.90+/-0.10 (melt). We have observed a good agreement between disso
lution kinetics and mixing enthalpies data.