TY - JOUR
T1 - The effect of egg albumin on the crystalline properties of carbamazepine in sustained release hydrophilic matrix tablets and in aqueous solutions
AU - Katzhendler, Ifat
AU - Azoury, Reuven
AU - Friedman, Michael
PY - 2000/4/3
Y1 - 2000/4/3
N2 - The influence of egg albumin (EA) on the crystal habit properties of carbamazepine (CBZ) in aqueous solutions, solid-state, and in sustained release matrix tablets was investigated using differential scanning calorimetry (DSC), hot-stage microscopy (HSM), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and contact angle goniometer (CAG). The results suggest that in solid-state mixtures, EA affected the polymorphic transitions of CBZ from the β to the α form. In hydrated matrix tablets and aqueous solutions, EA influenced the conversion rate of CBZ to the dihydrate form depending on EA concentration. It was found that increasing EA concentration enhanced CBZ dihydrate aggregation, an effect that leads to the formation of crystals with high mechanical strength and decrease of CBZ solubility. Possible mechanisms, which explain crystal growth and aggregation, as well as alteration of CBZ polymorphic transitions in the solid-state, gel layer, and in aqueous solution were suggested. In the gel layer of hydrated tablets the kinetics of CBZ transformation to the dihydrate form, crystal growth and aggregation were influenced by various processes: matrix hydration, erosion mechanism and the formation of metastable conditions, which favor aggregation and growth. The release kinetics of CBZ from the matrix highly correlated with the crystalline and morphological changes occurring in the matrix. (C) 2000 Elsevier Science B.V.
AB - The influence of egg albumin (EA) on the crystal habit properties of carbamazepine (CBZ) in aqueous solutions, solid-state, and in sustained release matrix tablets was investigated using differential scanning calorimetry (DSC), hot-stage microscopy (HSM), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and contact angle goniometer (CAG). The results suggest that in solid-state mixtures, EA affected the polymorphic transitions of CBZ from the β to the α form. In hydrated matrix tablets and aqueous solutions, EA influenced the conversion rate of CBZ to the dihydrate form depending on EA concentration. It was found that increasing EA concentration enhanced CBZ dihydrate aggregation, an effect that leads to the formation of crystals with high mechanical strength and decrease of CBZ solubility. Possible mechanisms, which explain crystal growth and aggregation, as well as alteration of CBZ polymorphic transitions in the solid-state, gel layer, and in aqueous solution were suggested. In the gel layer of hydrated tablets the kinetics of CBZ transformation to the dihydrate form, crystal growth and aggregation were influenced by various processes: matrix hydration, erosion mechanism and the formation of metastable conditions, which favor aggregation and growth. The release kinetics of CBZ from the matrix highly correlated with the crystalline and morphological changes occurring in the matrix. (C) 2000 Elsevier Science B.V.
KW - Carbamazepine
KW - Carbamazepine dihydrate
KW - Crystallinity
KW - Differential scanning calorimetry
KW - Egg albumin
KW - Polymorphism
KW - Scanning electron microscopy
KW - Sustained release
KW - X-ray diffraction
UR - http://www.scopus.com/inward/record.url?scp=0033997474&partnerID=8YFLogxK
U2 - 10.1016/S0168-3659(99)00124-8
DO - 10.1016/S0168-3659(99)00124-8
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C2 - 10699292
AN - SCOPUS:0033997474
SN - 0168-3659
VL - 65
SP - 331
EP - 343
JO - Journal of Controlled Release
JF - Journal of Controlled Release
IS - 3
ER -