Preparation and evaluation of microspheres of xyloglucan and its thiolated xyloglucan derivative.

Xyloglucan is a natural polymer reported to possess mucoadhesive properties. To enhance the mucoadhesion potential, xyloglucan was thiolated with cysteine. The microspheres of xyloglucan were prepared using a biocompatible crosslinker sodium trimetaphosphate and it was optimized for formulation variables, namely polymer concentration, internal:external phase ratio and stirring speed using a Box-Behnken experimental design. The formulation was also optimized for performance parameters like entrapment, t80 and % mucoadhesion. The microspheres were characterized by Fourier transform infrared spectroscopy, DSC and SEM for the optimum formula and then were reproduced by replacing the xyloglucan with thiomer. The microspheres formed showed entrapment efficiency of about 80%, t80 of about 400min and % mucoadhesion of 60% while same for thiomer were 90%, 500min and 80% respectively. In oral glucose tolerance test protocol the thiomer microspheres showed significant reduction in blood glucose levels. Thus thiolated xyloglucan offers a better polymer for multiparticulate drug delivery.

Development and comparative evaluation of in vitro, in vivo properties of novel controlled release compositions of paroxetine hydrochloride hemihydrate as against Geomatrix™ platform technology.

The objective of this study is to develop, in vitro and in vivo evaluation of novel approaches for controlled release of paroxetine hydrochloride hemihydrate (PHH) in comparison to patented formulation PAXIL CR(®) tablets of GlaxoSmithKline (Geomatrix™ technology). In one of the approaches, hydrophilic core matrix tablets containing 85% of the dose were prepared and further coated with methacrylic acid copolymer to delay the release. An immediate release coating of 15% was given as top coat. The tablets were further optionally coated using ethyl cellulose. In the second approach, hydrophobic matrix core tablets containing metharylic acid copolymer were prepared. In the third approach, PHH was granulated with enteric polymer and further hydrophobic matrix core tablets were prepared. The effect of polymer concentration, level of enteric coating on drug release was evaluated by in vitro dissolution study by varying dissolution apparatus and the rotation speeds. It was found that increase in concentration of high viscosity hydroxypropylmethylcellulose (HPMC) resulted in reduction of the release rate. The drug release was observed to be dependent on the level of enteric coating and ethyl cellulose coating, being slower at increased coating. The release mechanism of PHH followed zero-order shifting to dissolution dependent by the increase of HPMC content. The formulation was stable without change in drug release rate. In vivo study in human volunteers confirmed the similarity between test and innovator formulations. In conclusion, HPMC-based matrix tablets, which were further coated using methacrylic acid copolymer, were found to be suitable for the formulation of single layer-controlled release PHH.

Development and in vivo evaluation of novel monolithic controlled release compositions of galantamine hydrobromide as against reservoir technology.

The objective of this study is to develop and in vivo evaluation of novel monolithic matrix mini tablets approach to control the release of galantamine hydrobromide (GAH) in comparison with desired release profile to the Innovator formulation Razadyne(®) ER capsules. The direct compression method was employed for preparation of matrix mini tablets as against reservoir multiparticulate pellets of innovator formulation. The matrix swellings, dissolution similarity, mean dissolution time and dissolution efficiency of formulations were evaluated. It was found that increase in the concentration of high viscosity hydroxypropylcellulose (HPC) results reduction in release rate. The drug release was shown to be pH dependent with faster rate at lower pH. The release of GAH followed first order shifting to dissolution dependent by increase of HPC content. The formulation showed stability of drug release. In vivo prediction was done by Wagner-Nelson method. Prediction errors were estimated for Cmax and area under curve (AUC) and found to be not exceeding 15%. In vivo study in human volunteers confirmed the similarity between test and innovator formulations and pharmacokinetic values were comparable between actual and predicted. These results suggest that novel monolithic matrix approach could be suitable technique to formulate controlled release GAH.

Synthesis and characterization of a cysteine xyloglucan conjugate as mucoadhesive polymer

The aim of this study was to improve the mucoadhesive potential of xyloglucan polymer by the covalent attachment of cysteine as thiol moiety. The parent polymer xyloglucan was chemically modified by introducing sulphydryl bearing compound L-cysteine HCl. Different batches of xyloglucan-cysteine conjugates were prepared at varying reaction pH (2-6) and evaluated for optimum thiol incorporation, disulphide group content, swelling behavior, rheological properties and mucoadhesive properties. The obtained conjugates characterized in vitro by quantification of immobilized thiol groups; showed maximum thiol incorporation on xyloglucan (7.67 ± 0.14 %) at pH 5. The disulphide group content was found maximum (2.83 ± 0.12) at pH 6. The water uptake at end of 4 h was 5.0 for xyloglucan and was found to decrease in thiolated derivatives with increase in thiolation. Mucoadhesion studies revealed that mucoadhesion of xyloglucan-cysteine conjugate increased more than twice compared to the unmodified polymer. The viscosity of thiomer was more than that of xyloglucan because of formation of disulphide bonds.

O objetivo deste estudo foi melhorar o potencial mucoadesivo do polímero xiloglicano pela ligação covalente de cisteína como unidade de tiol. O polímero xiloglicano foi quimicamente modificado pela introdução de cloridrato de cisteína como grupo contendo sulfidrila. Prepararam-se diferentes lotes de conjugados cisteína-xiloglicano em pH variando de 2 a 6, avaliando-se a incorporação ótima de tiol, o conteúdo de dissulfeto, o comportamento de inchamento, as propriedades reológicas e mucoadesivas. Os conjugados obtidos foram caracterizados in vitro pela quantificação de grupos tiol, mostrando máxima incorporação na xiloglicana (7.67 ± 0.14 %) em pH 5. O conteúdo de grupos dissulfeto foi máximo (2.83 ± 0.12) em pH 6. O índice de inchamento em % no fim de 4 h foi 83.87 para o xiloglicano e diminuiu para os derivados tiolados. O conteúdo foi mínimo para TH2 (78.26), aumentou pouco até TH5 (83.33) e diminuiu, posteriormente, para TH6 (80.13). Os estudos de mucoadesão revelaram que o conjugado xiloglicano-cisteína aumentou mais que duas vezes comparativamente ao polímero não modificado. A viscosidade do tiômero foi maior do que a do xiloglicano devido à formação das ligações dissulfeto.

Controlled release reservoir mini tablets approach for controlling the drug release of Galantamine Hydrobromide.

The objective of this study is to explore and investigate the reservoir mini tablets approach to control the release of Galantamine Hydrobromide in comparison to desired release profile to the Innovator formulation Razadyne ER capsules as disclosed in US Patent 7,160,559 which is granted to Janseen Pharmaceutica NV. The core mini tablets were prepared using the direct compression and wet granulation methods. These core mini tablets were further coated with Galantamine Hydrobromide in two different portions; 70% as controlled release and 30% as immediate release and then filled in empty hard gelatin capsule shells. The dissolution profiles of each formulation were compared to those of Razadyne ER capsules and the mean dissolution time (MDT), dissolution efficiency (DE%) and dissolution similarity (f2 factor) were calculated. It was observed that core formulation plays an important role in controlling the drug release as well as maintaining pH independent drug release profile. The release mechanism of GAH from reservoir mini tablet formulation follows Higuchi and first order. These results imply that controlled release reservoir mini tablets which further filled into empty hard gelatin capsule shells can be a suitable method to formulate controlled release Galantamine hydrobromide.

Study on mechanism for amorphous drug stabilization using gelucire 50/13.

Methods of preparation and application of amorphous form are well established but it is equally important to note that devitrification of amorphous drugs has limited their applications. Present study was performed to investigate mechanism for amorphous drug stabilization using Gelucire in comparison with polyvinylpyrrolidone (PVP). Etoricoxib and celecoxib were taken as model drugs for this study, as etoricoxib has only proton accepting site for hydrogen bonding in comparison with celecoxib, which has both proton accepting and donating site. Solid dispersion of celecoxib with polyvinylpyrrolidone and Gelucire was prepared by spray drying and melt-granulation technique respectively. X-ray powder diffractometry and differential scanning calorimetry were used to study the physical state of the drug. Dissolution studies were performed to differentiate dissolution performance. Stability study samples were evaluated for physical state of the drug and dissolution performance. An IR study in correlation with molecular modeling was carried out to study the mechanism for stabilization. Dissolution of melt-granulation of amorphous celecoxib was improved significantly as compared to amorphous celecoxib and Celecoxib-PVP solid dispersion. Melt-granulation with lipid seemed to be more dominant than amorphization of drug for improving dissolution. Stability data revealed that PVP was significantly advantageous for amorphous form stabilization whereas Gelucire failed in case of Celecoxib. In contrast to this, our previous study revealed the stabilization ability of Gelucire for amorphous etoricoxib. Molecular modeling and IR studies revealed that H-bonding was predominant mechanism for stabilization. Out of two proposed mechanism for amorphous drug stabilization by lipids, H-bonding ability is more dominant than immobilization of molecule in lipid matrix.

Application of polyglycolized glycerides in protection of amorphous form of etoricoxib during compression.

Polymorphic transition and stability problems during amorphous drug formulation are the major limiting factors in pharmaceutical technology. The purpose of the study was to evaluate the ability of polyglycolized glycerides (Gelucire) in protection of amorphous form of drug during compression and shelf life with lower proportion. Amorphous etoricoxib (AET) was prepared by spray drying technique. Tablets of AET and melt granules of AET (MG-AET) with Gelucire 50/13 were prepared. Tablets parameters like hardness, disintegration and content uniformity were evaluated. Tablets were evaluated immediately after compression and on storage for 3 months at ambient conditions to determine degree of transformation using X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and dissolution profiles. Spray drying yielded the amorphous etoricoxib. Content uniformity in the tablet was in between 95 to 105%. Other parameters like disintegration and hardness were well within the limits. The results showed significant difference in the degree of crystallinity between AET tablet and MG-AET tablet. MG-AET tablet showed absence of crystallinity after 3 months storage. The reason could be formation of hydrogen bonding between the Gelucire and AET. Also Gelucire can be tableted very easily under low pressure and showed elastic recovery. Gelucire yielded a soft embedding during tableting, which prevented the polymorphic transformation. Polyglycolized glycerides (Gelucire 50/13) are able to protect amorphous etoricoxib during compression. As excipient required is low, it became possible to prepare tablet formulation as compared to other excipient like polyvinylpyrrolidon (PVP).

Development of spray-dried co-precipitate of amorphous celecoxib containing storage and compression stabilizers.

The purpose of this study was to obtain an amorphous system with minimum unit operations that will prevent recrystallization of amorphous drugs since preparation, during processing (compression) and further storage. Amorphous celecoxib, solid dispersion (SD) of celecoxib with polyvinyl pyrrollidone (PVP) and co-precipitate with PVP and carrageenan (CAR) in different ratios were prepared by the spray drying technique and compressed into tablets. Saturation solubility and dissolution studies were performed to differentiate performance after processing. Differential scanning calorimetry and X-ray powder difraction revealed the amorphous form of celecoxib, whereas infrared spectroscopy revealed hydrogen bonding between celecoxib and PVP. The dissolution profile of the solid dispersion and co-precipitate improved compared to celecoxib and amorphous celecoxib. Amorphous celecoxib was not stable on storage whereas the solid dispersion and co-precipitate powders were stable for 3 months. Tablets of the solid dispersion of celecoxib with PVP and physical mixture with PVP and carrageenan showed better resistance to recrystallization than amorphous celecoxib during compression but recrystallized on storage. However, tablets of co-precipitate with PVP and carageenan showed no evidence of crystallinity during stability studies with comparable dissolution profiles. This extraordinary stability of spray-dried co-precipitate tablets may be attributed to the cushioning action provided by the viscoelastic polymer CAR and hydrogen bonding interaction between celecoxib and PVP. The present study demonstrates the synergistic effect of combining two types of stabilizers, PVP and CAR, on the stability of amorphous drug during compression and storage as compared to their effect when used alone.

Evaluation of a drug with wax-like properties as a melt binder.

The study investigates ibuprofen with wax-like properties as a multifunctional agent (as an active component and as a melt binder). Binding efficiency was compared with granules prepared by wet granulation using polyvinylpyrollidone (PVP K-30) as a binder for micromeritic, physical and mechanical properties such as angle of repose, particle size distribution Carr's index, Hausner's ratio, crushing strength, percentage fines, Heckel plot study and tensile strength. To check the binder distribution during melt granulation, the content uniformity was determined. To check changes in the physical state of ibuprofen, XRPD, DSC and FTIR studies were carried out. The present study underlines the fact that ibuprofen may be adopted as a binder in ibuprofen formulations using the melt granulation technique.

Stabilization and improved in vivo performance of amorphous etoricoxib using Gelucire 50/13.

PURPOSE: Amorphous drugs have gained importance because of their advantageous biopharmaceutical properties; however, their stabilization remains a challenge. The purpose of this work was to stabilize the amorphous form of etoricoxib (ET) by using a low excipient/drug ratio to improve drug dissolution and thus bioavailability. METHODS: The effect of Gelucire and polyvinylpyrrolidone (PVP) on stabilization and bioavailability of amorphous etoricoxib (AET) was studied. X-ray powder diffractometry, differential scanning calorimetry, and scanning electron microscopy were used to study the physical state of the drug. Dissolution studies were performed for melt granules of AET with Gelucire 50/13 (MG-AET) and solid dispersion with PVP (SDP) to differentiate dissolution performance. A stability study on samples was conducted for 3 months to evaluate the physical state of the drug and its dissolution in the formulation. The in vivo performance of the optimized and stable formulation of ET was evaluated in rat. RESULTS: Dissolution of MG-AET was significantly improved as compared to AET and SDP. Both factors, amorphization of drug and melt granulation with lipid, seemed to be important for improving dissolution. Stability data revealed that MG-AET was significantly advantageous for AET stabilization, whereas PVP was not. The amount of Gelucire required for the stabilization of one part of AET was 0.5 part (by weight), whereas even 1.5 part (by weight) of PVP failed to elicit the same result. The superior in vivo performance of MG-AET has been attributed to the altered physiochemical properties of AET and the presence of lipid in the system. CONCLUSION: Gelucire can stabilize AET and improve its biopharmaceutical performance at a low excipient/drug ratio and may provide a better alternative to conventional stabilizers such as PVP.