Mechanism of increased dissolution of diazepam and temazepam from polyethylene glycol 6000 solid dispersions

Verheyen, Steven; Blaton, N. M.; Kinget, Renaat; Mooter, Guy Van den

doi:10.1016/s0378-5173(02)00532-x

Cited by 132 publications

(86 citation statements)

References 23 publications

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“…Samples with good dissolution have poor solubility after 24 hours and vice versa. This phenomenon could be attributed to the negative nature of Gibbs free energy changes and spontaneity of the process (12,14). Therefore, all the modified crystal forms of piroxicam with good dissolution have low solubility after 24 hours due to the transformation to a stable form with low solubility, except for piroxicam crystallized from acetone/benzene using method I. Piroxicam is almost insoluble in water and hence remains floating on the surface of the dissolution medium due to poor contact with the medium thereby resulting in a poor dissolution profile.…”

Section: Solubility and Dissolution Studiesmentioning

confidence: 99%

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Crystal modifications and dissolution rate of piroxicam

Lyn¹,

Sze²,

Rajendran³

et al. 2011

Acta Pharmaceutica

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Crystal modifications and dissolution rate of piroxicam Piroxicam is a nonsteroidal anti-inflammatory drug with low aqueous solubility which exhibits polymorphism. The present study was carried out to develop polymorphs of piroxicam with enhanced solubility and dissolution rate by the crystal modification technique using different solvent mixtures prepared with PEG 4000 and PVP K30. Physicochemical characteristics of the modified crystal forms of piroxicam were investigated by X-ray powder diffractometry, FT-IR spectrophotometry and differential scanning calorimetry. Dissolution and solubility profiles of each modified crystal form were studied and compared with pure piroxicam. Solvent evaporation method (method I) produced both needle and cubic shaped crystals. Slow crystallization from ethanol with addition of PEG 4000 or PVP K30 at room temperature (method II) produced cubic crystal forms. Needle forms produced by method I improved dissolution but not solubility. Cubic crystals produced by method I had a dissolution profile similar to that of untreated piroxicam but showed better solubility than untreated piroxicam. Cubic shaped crystals produced by method II showed improved dissolution, without a significant change in solubility. Based on the XRPD results, modified piroxicam crystals obtained by method I from acetone/benzene were cube shaped, which correlates well with the FTIR spectrum; modified needle forms obtained from ethanol/methanol and ethanol/acetone showed a slight shift of FTIR peak that may be attributed to differences in the internal structure or conformation.

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Section: Solubility and Dissolution Studiesmentioning

confidence: 99%

“…Crystallization process is also affected by the choice of additives (4,8,11,12). Addition of PEG 4000 and PVP K30 during recrystallization influenced the dissolution rate.…”

Section: Solubility and Dissolution Studiesmentioning

confidence: 99%

Crystal modifications and dissolution rate of piroxicam

Lyn¹,

Sze²,

Rajendran³

et al. 2011

Acta Pharmaceutica

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“…22 The preparation and storage conditions of the solid dispersions play a critical role, as changes may alter the dissolution characteristics of the active ingredients over time. [35][36][37][38][39][40][41] Drugs dispersed in the amorphous phase are expected to be more soluble than the crystalline or polymorphic forms. However, amorphous drugs are less stable and more sensitive to physical alterations during storage.…”

Section: Characterization Of Solid Dispersionsmentioning

confidence: 99%

Characterization of the distribution, polymorphism, and stability of nimodipine in its solid dispersions in polyethylene glycol by micro-Raman spectroscopy and powder x-ray diffraction

Docoslis

Huszarik

Papageorgiou

et al. 2007

AAPS J

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In the present study, a series of solid dispersions of the drug nimodipine using polyethylene glycol as carrier were prepared following the hot-melt method. Micro-Raman spectroscopy in conjunction with X-ray powder diffractometry was used for the characterization of the solid structure, including spatial distribution, physical state, and presence of polymorphs, as well as storage stability of nimodipine in its solid formulations. The effect of storage time on drug stability was investigated by examination of the samples 6 months and 18 months after preparation. Confocal microRaman mapping performed on the samples showed that the drug was not uniformly distributed on a microscopic level. The presence of crystals of nimodipine with sizes varying between one and several micrometers was detected, and the crystal size seemed to increase with overall drug content. In samples examined 6 months after preparation it was found that the crystals existed mainly as the racemic compound, whereas after 18 months of storage mainly crystal conglomerates were observed.

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“…In solid dispersion, the hydrophilic polymers that have been widely used as carriers are polyvinylpyrrolidone (PVP) and polyethylenoglycol (PEG), owing to their low cost, high solubility in water, and capacity to form dispersions in an amorphous state (8,9).…”

Section: Introductionmentioning

confidence: 99%

Solid Dispersions of Imidazolidinedione by PEG and PVP Polymers with Potential Antischistosomal Activities

Guedes¹,

Oliveira²,

Hernandes³

et al. 2011

AAPS PharmSciTech

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Abstract. Solid dispersions have been used as a strategy to improve the solubility, dissolution rate, and bioavailability of poor water-soluble drugs. The increase of the dissolution rate presented by (5Z)-3-(4-chloro-benzyl)-5-(4-nitro-benzylidene)-imidazolidine-2,4-dione (LPSF/FZ4) from the solid dispersions is related to the existence of intermolecular interactions of hydrogen bond type (>N-H ... O<) between the amide group (>N-H) of the LPSF/FZ4 and the ether group (-O-) of the polyethyleneglycol polymer, or the carbonyl (C=O) of the polyvinylpyrrolidone polymer (PVP). The intensity of these interactions is directly reflected in the morphology acquired by LPSF/FZ4 in these systems, where a new solid phase, in the form of amorphous aggregates of irregular size, was identified through scanning electron microscopy and confirmed in the characterizations achieved using X-ray diffraction and thermal analysis of DSC. The solid dispersions with the polymer PVP, in higher concentrations, were revealed to be the best option to be used in the formulations of LPSF/FZ4 in both theoretical and experimental studies.

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Mechanism of increased dissolution of diazepam and temazepam from polyethylene glycol 6000 solid dispersions

Cited by 132 publications

References 23 publications

Crystal modifications and dissolution rate of piroxicam

Crystal modifications and dissolution rate of piroxicam

Characterization of the distribution, polymorphism, and stability of nimodipine in its solid dispersions in polyethylene glycol by micro-Raman spectroscopy and powder x-ray diffraction

Solid Dispersions of Imidazolidinedione by PEG and PVP Polymers with Potential Antischistosomal Activities

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