Estimation of dissolution rate of salicylamide in complexing media using a theoretical diffusion model

Physicochemical characterization and dissolution properties of meloxicam-cyclodextrin binary systems

The objective of the work is physicochemical characterization of meloxicam (ME)-cyclodextrin (CD) binary systems both in solution and solid states and to improve the dissolution properties of meloxicam via complexation with alpha-, beta- and gamma-cyclodextrins. Detection of inclusion complexation was done in solution state by means of phase solubility analysis, mass spectrometry and 1H nuclear magnetic resonance (NMR) studies, and in solid state using differential scanning calorimetry (DSC), powder X-ray diffractometry, and in vitro dissolution studies. Phase solubility, mass spectrometry and 1H NMR studies in solution state revealed 1:1M complexation of meloxicam with all CDs. A true inclusion of ME with gamma-CD at 1:1 and 1:2M in solid state was confirmed by DSC, powder XRD and scanning electron microscopy (SEM) studies. Dissolution properties of ME-CDs binary systems were superior when compared to pure ME.

Physicochemical characterization and dissolution properties of nimesulide-cyclodextrin binary systems

The objective of this work is physicochemical characterization of nimesulide-cyclodextrin binary systems both in solution and solid state and to improve the dissolution properties of nimesulide (N) via complexation with alpha-, beta, and gamma-cyclodextrins (CDs). Detection of inclusion complexation was done in solution by means of phase solubility analysis, mass spectrometry, and 1H nuclear magnetic resonance (1H-NMR) spectroscopic studies, and in solid state using differential scanning calorimetry (DSC), powder x-ray diffractometry (X-RD), scanning electron microscopy (SEM), and in vitro dissolution studies. Phase solubility, mass spectrometry and 1H-NMR studies in solution revealed 1:1 M complexation of N with all CDs. A true inclusion of N with beta-CD at 1:2 M in solid state was confirmed by DSC, powder X-RD and SEM studies. Dissolution properties of N-CD binary systems were superior when compared to pure N.

Improvement of the in vitro dissolution of praziquantel by complexation with alpha-, beta- and gamma-cyclodextrins

Although praziquantel (PZQ) is the primary drug of choice in the treatment of schistosomiasis, its poor solubility has restricted its delivery via the oral route. In spite of its poor solubility, PZQ is well absorbed across the gastrointestinal tract, but large doses are required to achieve adequate concentrations at the target sites. Improving the solubility would enable the parenteral route to be used, thereby avoiding significant first pass metabolism. The aqueous solubility of PZQ was improved by forming inclusion complexes with alpha-, beta- and gamma-cyclodextrins (CDs). These complexes were assessed and confirmed by solubility analysis, Fourier transform infrared analysis, elemental analysis, differential scanning calorimetry and mass spectrometry. Dissolution of PZQ from the alpha-, beta- and gamma-CD complexes was 2.6-, 5- and 8-fold greater, respectively, than that of the pure drug. However, only the beta-complex had a stability constant in the optimum range for pharmaceutical use, suggesting that the preferred complex for further development would be a water-soluble beta-CD derivative.

The effect of protein on the dissolution of phenytoin

Ultrafiltration of a continuous flow system was used to follow the dissolution of phenytoin powder in buffered solutions of pH 1, 4 and 7.4. The presence of either human serum albumin (HSA) or casein caused changes in both the absolute solubility and the dissolution rate. Normal protein binding cannot be responsible for the effects noted. It would seem likely that within the diffusion layer a higher degree of protein binding occurs than is possible in the bulk aqueous solution. The drug solubilized in this way is then released in solution in a form that is at least metastable with respect to phenytoin in normal solution. The effect of protein on phenytoin dissolution may well affect the bioavailability of the drug.

Inclusion complexation of prostaglandin F2 alpha with gamma-cyclodextrin in solution and solid phases

A solid complex of prostaglandin F2 alpha (dinoprost) with gamma-cyclodextrin in a molar ratio of 1:1 was obtained on the basis of the BS-type phase solubility diagram. The mode of interaction in the solid state was studied by powder X-ray diffractometry, thermal analysis, and carbon-13 cross polarization/magic angle spinning nuclear magnetic resonance (13C-CP/MAS-NMR) spectrometry. The X-ray diffraction and NMR data suggested that prostaglandin F2 alpha is included in the cylindrical channels formed by coaxial alignment of gamma-cyclodextrin molecules to give a channel type structure. Dissolution and thermal behaviors of the prostaglandin F2 alpha-gamma-cyclodextrin complex were examined and compared with the drug itself. The result indicated that the gamma-cyclodextrin complex may have great utility as a rapidly dissolving form of prostaglandin F2 alpha with improved thermal stability.