Effect of hydrophilic polymers on the solubility and dissolution enhancement of rivaroxaban/beta-cyclodextrin inclusion complexes.

BCS class II drugs exhibit low aqueous solubility and high permeability. Such drugs often have an incomplete or erratic absorption profile. This study aimed to predict the effects of ß-cyclodextrin (ßCD) and different hydrophilic polymers (poloxamer 188 (PXM-188), polyvinyl pyrrolidone (PVP) and soluplus (SOLO)) on the saturated solubility and dissolution profile of hydrophobic model drug rivaroxaban (RIV). Binary inclusion complex with ßCD were prepared by kneading and solvent evaporation method, at drug to cyclodextrin weight molar ratios of 1:1, 1:2, and 1:4. Saturated solubility of the hydrophobic model moiety was evaluated with ßCD to explore the increment in saturated solubility. Dissolution test was carried out to assess the drug release from the produced binary inclusion complex in the aqueous medium. Solid state analysis was performed using Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Scanning electron microscopy (SEM) techniques. When compared to pure drug, the binary complex (Drug: ßCD at molar ratio of 1:2 w/w) demonstrated the best performance in terms of enhanced solubility and drug release. Furthermore, ternary inclusion complex was prepared with hydrophilic polymers SOLO, PVP K-30 and PXM-188 at 0.5%,1%,2.5%,5% and 10% w/w to optimized binary formulation RIV:ßCD (1:2) prepared by kneading (KN) and solvent evaporation (S.E) method. The findings demonstrated that among ternary formulations (1:2 Drug: ßCD: SOLO 10% S.E) manifested greatest improvement in saturated solubility and dissolution rate. Results of solubility enhancement and improvement in dissolution profile of model drug by ternary inclusion complexation were also supported by FTIR, DSC, XRD, and SEM analysis. So, it can be concluded that the ternary inclusion systems were more effective compared to the binary combinations in improving solubility as well as dissolution of hydrophobic model drug rivaroxaban.

Prediction of CYP-mediated silybin A-losartan pharmacokinetic interactions using physiological based pharmacokinetic modeling.

The concomitant use of herbal products and synthetic drugs necessitates the assessment of their interaction potentials. The herbal hepatoprotective medicine, silybin A inhibits cytochrome P450 (CYP) 2C9 and 3A4 enzymes, thus, may interact with the drugs that are substrates of CYP2C9 and 3A4, such as losartan. The three most prominent genotypes, expressed by CYP2C9 are the CYP2C9*1/*1, CYP2C9*1/*2 and CYP2C9*1/*3. This study aimed to assess silybin A-losartan interaction in different CYP2C9 genotypes using physiological-based pharmacokinetic (PBPK) model approach. The individual PBPK models for silybin A and losartan were developed using PK-Sim®. Losartan pharmacokinetics was predicted with or without co-administration of silybin A in individuals of different CYP2C9 genotypes to find herbal-drug interaction. The predicted drug plasma curves and pharmacokinetic parameters were optimized using parameter identification tool and were compared with reported pharmacokinetic parameters from the published clinical studies for model validation. The silybin-losartan interactions were predicted by change in area under the curve (AUC) and peak systemic concentration (Cmax). The co-treatment of silybin A, 420 mg/24 h (140 mg/8 h) with losartan 50 mg/24 h, exhibited a genotype-dependent change in the losartan's AUC and Cmax. In CYP 2C9*1/*1 genotype, AUC and Cmax of losartan were increased 1.16 and 1.37 folds, respectively falling in a range stipulated for negligible interaction. Increase in AUC and Cmax by 0.873 and 0.294 folds, respectively in CYP2C9*1/*3 after co-administration of silybin A exhibited a minor interaction with losartan. However, in individuals with CYP2C9*1/*2 genotype, the losartan's AUC and Cmax were decreased by 0.01 folds, manifesting a moderate interaction. Hence, in CYP2C9*1/*1 and CYP2C9*1/*3 genotypes, silybin A is a weak CYP inhibitor for losartan while in CYP2C9*1/*2 genotype, the co-administration of silybin consequents into a moderate pharmacokinetic interaction with losartan.

Effect of Hydrophilic Polymers on Complexation Efficiency of Cyclodextrins in Enhancing Solubility and Release of Diflunisal.

The effects of three hydrophilic polymers, namely, carboxymethyl cellulose sodium (CMC-Na), polyvinyl alcohol (PVA) and poloxamer-188 (PXM-188) on the solubility and dissolution of diflunisal (DIF) in complexation with ß-cyclodextrin (ßCD) or hydroxypropyl ß-cyclodextrin (HPßCD), were investigated. The kneading method was used at different drug to cyclodextrin weight ratios. Increases in solubility and drug release were observed with the DIF/ßCD and DIF/HPßCD complexes. The addition of hydrophilic polymers at 2.5, 5.0 and 10.0% w/w markedly improved the complexation and solubilizing efficiency of ßCD and HPßCD. Fourier-transform infrared (FTIR) showed that DIF was successfully included into the cyclodextrin cavity. Differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) confirmed stronger drug amorphization and entrapment in the molecular cage of cyclodextrins. The addition of PVA, CMC-Na or PXM-188 reduced further the intensity of the DIF endothermic peak. Most of the sharp and intense peaks of DIF disappeared with the addition of hydrophilic polymers. In conclusion, PXM-188 at a weight ratio of 10.0% w/w was the best candidate in enhancing the solubility, stability and release of DIF.

Binary inclusion complexes of diflunisal with ß-cyclodextrin and hydroxypropyl-ß-cyclodextrin: Preparation and characterization.

Low aqueous solubility and bioavailability is the limiting factor to achieve desired therapeutic efficacy for variety of new and existing drug moieties. The goal of the present study was to explore the effects of ß-cyclodextrin (ßCD) and hydroxypropyl-ß-cyclodextrin (HPßCD) on the solubility and dissolution profile of diflunisal (DIF) prepared by using two different methods (physical mixing and solvent evaporation) at DIF-cyclodextrins weight ratios of 1:1, 1:2 and 1:4. The phase solubility studies demonstrated that DIF solubility increased proportionally with an increase in ßCD and HPßCD concentration. The inclusion complexes were subjected to characterization of scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). Solvent evaporation yielded higher DIF solubility than physical mixing method. HPßCD-DIF inclusion complexes yielded higher dissolution profile than ßCD complexes when prepared under same experimental design. FTIR, DSC and XRD confirmed the successful inclusion of DIF into cyclodextrin (ßCD/HPßCD) by both preparation methods with enhanced water solubility and drug release in comparison with pure drug.

Stability indicating RP-HPLC method of dexibuprofen in nanocream formulation: Identification and quantification.

A stability indicating reverse phase-HPLC method was designed for determination of dexibuprofen in drug solution and in nanocream formulation. Chromatographic conditions were optimized simply by adjusting the content and different compositions of reverse phase associated with mobile phases. Different parameters like specificity, limit of quantification (LOQ), limit of detection, linearity, range, system suitability, precision and accuracy were determined. Stability studies of dexibuprofen in nanocream were taken under the stressed situations of alkali, acid, oxidation process, UV and heat degradation. Tailing factor and % RSD were found >2000 and <2% respectively. The method was identified linear over the range of 0.2-1.6mg/ml having co-efficient of correlation 0.9995. Intra-day and inter- day precision and accuracy values for dexibuprofen were < 0.6% and <1.1032 and < 0.3% and 1.10% respectively. Stability studies showed that dexibuprofen was stable in nanocream against alkali, acid, oxidation, UV light and heat. The developed validated method was precise and accurate for the evaluation of dexibuprofen in solution as well as in nanocream formulation.

Decompressive hemicraniectomy in supra-tentorial malignant infarcts.

BACKGROUND: Decompressive hemicraniectomy not only reduces the intracranial pressure but has been demonstrated to increase survival and decrease the morbidity in patients with supratentorial malignant brain infarcts (STMBI). The aim of this study was to assess the efficacy of surgical decompression to decrease the mortality and morbidity in patients with STMBI refractory to medical therapy and to compare the results with those of the medically managed patients. METHODS: All the 24 consecutive patients with clinical and radiological diagnosis of STMBI, refractory to medical management in 2 years, were included. Option of surgical decompression after explaining the outcome, risk and benefits of the procedure was given to the attendants/relatives of all patients who were fulfilling the inclusion criteria. The patient group, whose attendants/relatives were not willing to undergo surgery, were subjected to the same medical therapy and they were taken as the "control group." RESULTS: Supratentorial malignant infarcts were more common in the age group of 41-60 years. Mean age of presentation was 42.16 ± 16.2 years and the mean GCS on admission was 7.83 ± 2.1. Mortality was 16.7% in the surgically and 25.0% in the medically managed group. Patients operated early (<48 h), age ≤60 years, midline shift <5 mm and size of infarct less than 2/3(rd) of the vascular territory involved showed good prognosis. The functional outcome revealed by modified Rankin Score (mRS) and Glasgow Outcome Score (GOS) was better in surgically managed patients. Results of the Zung Self-Rating Depression Score were better in surgically managed patients at 1 year. Barthal Index in the surgically managed group showed statistically significant results. CONCLUSIONS: Decompressive hemicraniectomy with duroplasty if performed early in STMBI not only decreases the mortality but also increases the functional outcome when compared with patients who were managed conservatively with medical therapy only.