Solid Dispersion Granules Research Articles

Hydroxypropyl-β-cyclodextrin-based solid dispersed granules: A prospective alternative to conventional solid dispersion

The purpose of the present study was to develop hydroxypropyl-β-cyclodextrin (HP-β-CD)-based solid dispersed granules as a superior system to solid dispersion. The solid dispersed granules and solid dispersion were compared in terms of powder property improvement, solubility increment and oral bioavailability enhancement of poorly water-soluble dexibuprofen. Solid dispersion (drug/HP-β-CD/Tween80 = 1:7:0.1, weight ratio) and solid dispersed granules (drug/HP-β-CD/Tween80/Microcrystalline cellulose = 1:7:0.1:4) were fabricated using a spray-dryer and fluid bed granulator, respectively. The HP-β-CD-based solid dispersed granules significantly improved solubility, dissolution profile and oral bioavailability of dexibuprofen compared to pure drug powder. Moreover, the solid dispersed granules maximised the oral bioavailability of dexibuprofen to the same extent as the solid dispersion. However, considerable improvements of powder and tablet properties were observed in solid dispersed granules as compared with solid dispersion. Therefore, HP-β-CD-based solid dispersed granules would be a prospective alternative to solid dispersion.

Preparation and Characterization of pH-Independent Sustained-Release Tablets Containing Hot Melt Extruded Solid Dispersions of Clarithromycin : Tablets Containing Solid Dispersions of Clarithromycin.

The limited solubility of clarithromycin (CAM), coupled with low bioavailability and rapid elimination, are major shortcomings, needed to be addressed to achieve optimum therapeutic goals. Therefore, sustained-release (SR) tablets containing solid dispersion (SD) granules of CAM were prepared in this study. Initially, SD granules of CAM were prepared by hot melt extrusion (HME) technique using Kollidon VA64 as a hydrophilic carrier. The saturation solubility of SD showed almost 4.5-fold increase as compared to pure CAM in pH 6.8 medium. In vitro drug dissolution data indicated a substantial increase in the dissolution of SD as compared to that of pure CAM. The thermal stability of drug, carrier, and SD at elevated HME temperatures was evident from the results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Powder X-ray diffraction (PXRD) data and scanning electron microscope (SEM) images revealed a decrease in the crystallinity and the uniform dispersion of drug, respectively. Moreover, Fourier transformed infrared spectroscopy (FT-IR) data confirmed the formation of hydrogen bond between the carbonyl group of drug and the hydroxyl group of carrier. SD loaded sustained-release (SD-SR) matrix tablets were prepared with hydrophobic polymers (Eudragit RS100 and Eudragit RL100). The pH-independent swelling and permeability of both polymers were responsible for the sustained drug release from SD-SR tablets. Pharmacokinetic (PK) studies suggested a 3.4-fold increase in the relative bioavailability of SD-SR tablets as compared to that of pure CAM.

Physical stability and release properties of lumefantrine amorphous solid dispersion granules prepared by a simple solvent evaporation approach

Amorphous solid dispersions (ASDs) of lumefantrine, which has low aqueous solubility, have been shown to improve bioavailability relative to crystalline formulations. Herein, the crystallization tendency and release properties of a variety of lumefantrine ASD granules, formed on a blend of microcrystalline cellulose and anhydrous lactose, prepared using a simple solvent evaporation method, were evaluated. Several polymers, a majority of which contained acidic moieties, and different drug loadings were assessed. Crystallinity as a function of time following exposure to stress storage conditions of 40 °C and 75% relative humidity was monitored for the various dispersions. Release testing was performed and ASD characteristics were further evaluated using infrared and X-ray photoelectron spectroscopy (XPS). A large difference in stability to crystallization was observed between the various ASDs, most notably depending on polymer chemistry. This could be largely rationalized based on the extent of drug-polymer interactions, specifically the degree of lumefantrine-polymer salt formation, which could be readily assessed with XPS spectroscopy. Lumefantrine release from the ASDs also varied considerably, whereby the best polymer for promoting physical stability did not lead to the highest extent of drug release. Several formulations led to concentrations above the amorphous solubility of lumefantrine, with the formation of nano-sized drug-rich aggregates. A balance between the ability of a given polymer to promote physical stability and drug release may need to be sought.

Preparation and Evaluation of Controlled-Release Solid Dispersion Granules Containing a Poorly Water-Soluble Drug, Hydrated Silicon Dioxide, and Polyvinylpyrrolidone

Preparation and Evaluation of Controlled-Release Solid Dispersion Granules Containing a Poorly Water-Soluble Drug, Hydrated Silicon Dioxide, and Polyvinylpyrrolidone

Characterization of Amorphous Solid Dispersion of Pharmaceutical Compound with pH-Dependent Solubility Prepared by Continuous-Spray Granulator.

A continuous-spray granulator (CTS-SGR) is a one-step granulation technology capable of using solutions or suspensions. The present research objectives were, (1) to reduce the manufacturing operations for solid dosage formulations, (2) to make amorphous solid dispersion (ASD) granules without pre-preparation of amorphous solids of active pharmaceutical ingredients (API), and (3) to characterize the obtained SGR granules by comprehensive pharmaceutical analysis. Rebamipide (RBM), a biopharmaceutical classification system class IV drug, that has low solubility or permeability in the stomach, was selected as a model compound. Five kind of granules with different concentrations of polyvinylpyrrolidone/vinyl acetate copolymer (PVP-VA) were prepared using a one-step SGR process. All of the SGR granules could be produced in amorphous or ASD form and their thermodynamic stability was very high because of high glass transition temperatures (>178 °C). They were unstable in 20 °C/75%RH; however, their stability was improved according to the proportion of polymer. The carboxy group of RBM was ionized in the granules and interactions appeared between RBM and PVP-VA, with the formation of an ASD confirmed and the solubility was enhanced compared with bulk RBM crystals. The SGR methodology has the possibility of contributing to process development in the pharmaceutical industry.

Early formulation development of CKD-519, a new CETP inhibitor, for phase 1 clinical study based on in vitro and in vivo evaluation

CKD-519, a potent cholesteryl ester transfer protein (CETP) inhibitor, is a clinical candidate being developed for the treatment of dyslipidemia. It is considered a Biopharmaceutical Classification System II compound with low solubility and high permeability. The objective of this study was to develop early formulations focusing on the dissolution rate of the compound to achieve dose-dependent exposure. High performance formulation strategies including solid dispersion (SD) and a self-microemulsifying drug delivery system (SMEDDS) were investigated and their in vivo and in vitro correlations were also evaluated in monkeys along with dose optimization in human volunteers. The SD granules were prepared in a fluid bed granulator using microcrystalline cellulose and mannitol as carriers. Poloxamer 407 and Eudragit E PO were each found to be a suitable solubilizing agent and polymer for the improvement of the CKD-519 dissolution rate. Pharmacokinetic studies in monkeys showed that the SD tablets exhibited better absorption than the SMEDDS in a dose-dependent manner from 1.5 mg to 100 mg. The mannitol-based SD tablet formulations were bioequivalent. However, pharmacokinetics studies in humans showed that the dose was saturable above 100 mg of CKD-519. This study was performed to determine how to develop early formulations for clinical studies and to identify rational formulation development strategies for CKD-519 to establish the pharmaceutical proof-of-concept in humans.

Mesoporous Pravastatin Solid Dispersion Granules Incorporable Into Orally Disintegrating Tablets

Herein, we aimed to prepare porous granules of pravastatin and evaluate their applicability to orally disintegrating tablets (ODTs). Pravastatin solid dispersion granules (PSDGs-A) were prepared by dispersing pravastatin sodium in D-mannitol (the dispersion medium) in the presence of ammonium bicarbonate (the sublimation agent) using a spray-drying process. The PSDGs-A were round, irregularly shaped, mesoporous agglomerates with appropriate particle size, bulk density, and flowability for the tableting process. The mesopore formation in PSDGs-A resulted from the complete sublimation of ammonium bicarbonate during spray-drying and resulted in a notably high surface area. When the PSDGs-A were blended with ODT excipients and then directly compressed into ODTs (PSDGs-A-ODTs), they were readily incorporated into ODTs without tableting problems and had desirable ODT characteristics. They demonstrated rapid disintegration times because of the fast water uptake of mesoporous PSDGs-A caused by their high surface area. This rapid disintegration of PSDGs-A-ODTs was reflected also by their quick initial dissolution. The mesoporous PSDGs-A prepared with ammonium bicarbonate using the spray-drying process can be used to develop pravastatin ODTs. This spray-dried, mannitol-based solid dispersion of drugs using sublimation solids is a potential formulation technology for ODT product development.

ENHANCEMENT OF SOLUBILITY AND DISSOLUTION OF IBUPROFEN BY SOLID DISPERSION TECHNIQUE AND FORMULATION OF SUSTAINED RELEASE TABLETS CONTAINING THE OPTIMISED BATCH OF SOLID DISPERSION

Objective: The present study was aimed to enhance the solubility of poorly water soluble drug Ibuprofen using solid dispersion technique and to develop sustained release tablets containing solid dispersion granules of the optimized batch. Ibuprofen is a non-steroidal anti-inflammatory drug (NSAID) with analgesic, antipyretic, and anti-inflammatory propertiesMethods: Solid dispersions of Ibuprofen were prepared by using PEG 20000 and Poloxamer 407 in different weight ratios by fusion and solvent evaporation method. Drug-carrier physical mixtures were also prepared. Solid dispersions were characterized by saturation solubility, drug content, in vitro dissolution, FTIR and DSC analysis. Solid dispersion formulation, SDF9 (PEG 20000 and Poloxamer 407, 1:3:3) prepared by solvent evaporation method was considered as the optimized batch. Sustained release tablets containing the solid dispersion granules of the optimized batch were prepared by direct compression method using HPMC K100M at three concentrations (10%, 14%, 18% w/w). The prepared formulations were evaluated for hardness, thickness, weight variation, friability, in vitro dissolution studies and release kinetics modelling.Results: Solid dispersion formulation, SDF9showed 95.09% drug release in 60 min and considered as the optimized batch. Tablet formulation, FT3 (HPMC K100M 18% w/w) showed 96% drug release for 12 h.Conclusion: Solid dispersions of ibuprofen using a combination of PEG 20000 and poloxamer 407 by solvent evaporation method may result in higher aqueous solubility of the drug. Also sustained release tablets containing solid dispersion granules of ibuprofen, using HPMC K100M may be a promising approach to extend the release rate of the drug from the solid dispersion for 12 h.

Development of extended-release solid dispersion granules of tacrolimus: evaluation of release mechanism and human oral bioavailability

We aimed to prepare a once-daily modified-release oral formulation of tacrolimus by utilizing an extended-release granules (ERG). Extended-release granules were prepared using ethylcellulose (EC), hydroxypropylmethylcellulose (HPMC) and lactose via a solvent evaporation method with ethanol. Physicochemical and biopharmaceutical studies were performed to determine the formulation with optimum release profile of tacrolimus from ERG. Tacrolimus existed in an amorphous state in ERG. Tacrolimus release from ERG was attenuated by EC and facilitated by lactose, suggesting that drug release kinetics could adequately be regulated by these components. Those release profiles were consistent with Higuchi's equation, suggesting a diffusion-type release mechanism. Smooth surface of ERG changed to the structure with pores after the release test, likely derived from the dissolution of HPMC and lactose. But ERG structure formed by EC was still maintained after the release test, leading to the longer maintenance of diffusion-type release. Two ERG formulations selected by blood concentration simulation successfully provided long-term retention of tacrolimus in blood in a human absorption study. We successfully developed the formulation exhibiting a significant reduction in Cmax , the longer mean residence time and AUC close to that of an immediate-release tacrolimus formulation, being preferred from the viewpoint of safe and effective immunosuppressant pharmacotherapy.

Novel tablet formulation of amorphous indomethacin using wet granulation with a high-speed mixer granulator combined with porous calcium silicate

Solid dispersion techniques are useful for improving the dissolution of poorly water-soluble drugs. This study aimed to produce and evaluate solid dispersion tablets improving the solubility and oral bioavailability of a poorly water-soluble indomethacin (IND) by wet granulation method with a high-speed mixer granulator combined with porous calcium silicate (PCS). A low density of PCS is a major disadvantage which is a bulky volume and scattering. So, it is necessary to prepare a high density PCS granule. Our system is very simple. At first, IND ethanol solution was added to PCS in a high-speed mixer granulator. After mixing, the granulation started the addition of the binder water solution to the PCS/IND mixture. The solid dispersion granules were obtained after drying the mixture. The dissolution rates of IND from PCS tablets were markedly enhanced compared with the dissolution rate of the pure drug. IND did not recrystallize in granules prepared using water and this formulation provided superior bioavailability in rats. Our amorphous solid dispersions have been successfully employed to enhance both solubility and oral bioavailability of IND. Though the use of PCS, it may be possible to maximize the bioavailability benefit of amorphous solid dispersions administered as tablet dosage forms.

Preparation and Evaluation of Solid Dispersion Tablets by a Simple and Manufacturable Wet Granulation Method Using Porous Calcium Silicate.

The aim of this study was to prepare and evaluate solid dispersion tablets containing a poorly water-soluble drug using porous calcium silicate (PCS) by a wet granulation method. Nifedipine (NIF) was used as the model poorly water-soluble drug. Solid dispersion tablets were prepared with the wet granulation method using ethanol and water by a high-speed mixer granulator. The binder and disintegrant were selected from 7 and 4 candidates, respectively. The dissolution test was conducted using the JP 16 paddle method. The oral absorption of NIF was studied in fasted rats. Xylitol and crospovidone were selected as the binder and disintegrant, respectively. The dissolution rates of NIF from solid dispersion formulations were markedly enhanced compared with NIF powder and physical mixtures. Powder X-ray diffraction (PXRD) confirmed the reduced crystallinity of NIF in the solid dispersion formulations. Fourier transform infrared (FT-IR) showed the physical interaction between NIF and PCS in the solid dispersion formulations. NIF is present in an amorphous state in granules prepared by the wet granulation method using water. The area under the plasma concentration-time curve (AUC) and peak concentration (C(max)) values of NIF after dosing rats with the solid dispersion granules were significantly greater than those after dosing with NIF powder. The solid dispersion formulations of NIF prepared with PCS using the wet granulation method exhibited accelerated dissolution rates and superior oral bioavailability. This method is very simple, and may be applicable to the development of other poorly water-soluble drugs.

Hibiscus Rosa-Sinesis Leaves Polysaccharide as Solubility Enhancing Agent for Poorly Soluble Drug

The main purpose of this research was to use hydrophilic Hibiscus Rosa-sinesis (HRS) dry leaves mucilage as functionality solubility enhancing agent for the design and development of solid dispersion of the drug Telmisartan (TS) to formulate tablets and to study its in vitro quality control tests. The mucilage was extracted, isolated, purified and prepared solid dispersions with different ratio of drug: mucilage (1:0.5, 1:1.0, 1:1.5, 1:2.0 and 1:2.5) using solvent evaporation method and another. Two formulations were prepared using drug: mucilage ratio of 1:1.0 as co-grinding method (GM) and physical mixture (PM). The solubility study showed a significant enhancement in the aqueous solubility of the drug where the solubility rate was increased with the increment in ratio of the mucilage. The formulation giving the best solubility enhancement of Telmisartan in aqueous media was in the order of SD > GM > PM > API. Then, the dispersions were compressed into tablets where it passed the precompression and post-compression evaluation parameters. Swelling index increased as the amount of mucilage added to each formulation (SD1 to SD3). Nevertheless as the amount of mucilage is increased for formulation SD4 and SD5 (1:2.0 and 1:2.5 ratio of drug: mucilage) the swelling index were decreased. The in-vitro dissolution study revealed that there is marked decrease in the dissolution rate of Telmisartan for all the solid dispersion containing tablets when compared to Telmisartan API tablets. This proves with the increase in mucilage ratio, the drug release from the solid dispersion tablet got retarded because of the formation of highly viscous barrier layer at the interface of the tablet and dissolution medium. In conclusion, the solubility of the drug has been greatly enhanced by the solid dispersion technique incorporating HRS mucilage using solvent evaporation method. Therefore, it is suggested that the drug Telmisartan can be converted to solid dispersion using Hibiscus Rosa-sinesis dry leaves mucilage as solubility enhancing agent and the solid dispersion granules can be filled in capsules as a dosage form.

Development of sustained release tablets containing solid dispersions of baclofen

Sustained release tablets containing solid dispersions granules of a poorly water soluble drug were prepared to investigate the controlled release of the drug. Baclofen was chosen because of its poor water solubility and short elimination half-life. Poloxamer 188 and PEG 6000 were used as solid dispersion carrier. Free flowing solid dispersion granules were prepared by adsorbing the melt of the drug and carriers onto the surface of an adsorbent, Carbopol 934P followed by direct compression with HPMC K4M and HPMC K100 to obtain an solid dispersion loaded sustained release tablets. FTIR studies confirmed that the compatibility of drug and carriers. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) revealed partially amorphous structures of the drug in solid dispersion granules. The solid dispersion granules dissolved completely within 30 min, which was much faster than that of pure drug baclofen. The sustained release of baclofen from the solid dispersion containing tablet was achieved for 2 h in gastric fluid (pH 1.2) and for up to 10 h in intestinal fluid (pH 6.8). A combination of solid dispersion techniques using adsorption and sustained release concepts is a promising approach to control the release rate of poorly water-soluble drugs. Keywords: Solid dispersion; baclofen; sustained release; adsorbent.

Enhanced oral bioavailability of paclitaxel by solid dispersion granulation

The main objective of this study was to develop novel orally administrable tablets containing solid dispersion granules (SDG) of amorphous paclitaxel (PTX) prepared by fluid bed technology, and to evaluate its in vitro dissolution and in vivo pharmacokinetics (PK) in beagle dogs. The SDG were prepared using optimized composition by fluid bed technology, and characterized for solid-state properties. The release study of SDG tablet (SDG-T) in simulated gastric fluid showed a rapid release of PTX, reaching maximum dissolution within 20 min. Finally, the PK profile of SDG-T and a reference formulation Oraxol™ (oral solution formulation used in Phase I clinical study) at a dose of 60 mg orally with co-administration of P-gp inhibitor HM38101, and Taxol® at a dose of 10 mg intravenously (i.v.) was investigated in beagle dogs. The mean absolute BA% of PTX following SDG-T and Oraxol™ solution was 8.23 and 6.22% in comparison to i.v. administration of Taxol®. The relative BA% of PTX from SDG-T in comparison to Oraxol™ solution was 132.25% at a dose of 60 mg following oral administration. In conclusion, we have successfully prepared PTX tablets with solid dispersion granules (SDG) of amorphous PTX using fluid bed technology that could provide plasma PTX concentration in the range of 10–150 ng/mL for a period of 24 h following oral administration in dogs with a P-gp inhibitor. Hence, this could be a promising formulation for PTX oral delivery and could be used in our intended clinical studies following pre-clinical efficacy studies.

Improved bioavailability and antiasthmatic efficacy of poorly soluble curcumin-solid dispersion granules obtained using fluid bed granulation

The intestinal absorption and antiasthmatic efficacy of poorly water-soluble curcumin (CUR), which has low solubility and permeability, was increased by fabricating solid dispersion granules (SDGs). The SDG containing CUR (SDG-CUR) was prepared by dispersing CUR in excess Cremophor RH40 as a solubilizer and Ryoto sugar ester L-1695 as an absorption enhancer using fluid bed granulation. We evaluated the physicochemical properties such as crystallinity and dissolution, pharmacokinetics, and antiasthmatic efficacy of SDG-CUR. Our results showed that CUR was molecularly dispersed, and the dissolution of SDG-CUR was significantly higher than that of native CUR. In addition, the blood concentration of SDG-CUR in rats was much higher than that of native CUR. Compared to CUR, SDG-CUR showed a 9.1- and 13.1-fold increase in area under the plasma concentration-time curve (AUC) and maximum plasma concentration (Cmax), respectively. Further, SDG-CUR effectively alleviated airway hyperresponsiveness and levels of T-helper 2 cytokines (interleukin-4, interleukin-5, and interleukin-13) in a murine model of asthma. In conclusion, our results suggest that the SDGs could be considered as a potential oral formulation to enhance the absorption and efficacy of CUR.

Formulation and pharmacokinetic evaluation of once-daily sustained-released system of nifedipine with solid dispersion and coating techniques

A novel sustained-release system was developed for poorly water-soluble drugs by applying solid dispersion (SD) technique to improve the solubility. The SD systems composed of polyvinyl pyrrolidone and stearic acid could not control the release of nifedipine. When the above SD granules were coated with ethylcellolulose (EC10, 45 and 100cp), the dissolution rate extended from 16 to 20 h. When the concentration of EC100cp was increased to 4-6 %, the sustained-release formulation F7 and F8 prepared with 4 % EC100cp and 6 % EC100cp, respectively, could control the drug release in a better manner, namely, they could control drug release in the initial hours with a high cumulative amount of drug at 24 h. The mechanism of drug release from F7 and F8 was diffusion coupled with erosion. When immediate-release capsules was orally administered to rabbits, its absorption was very rapid with a short elimination half-life, while a prolonged maintenance of the plasma drug level up to 24 h was obtained for F7 and F8. Furthermore, the oral bioavailability of F7 and F8 was significantly improved. The results suggested that this novel sustained-release system would be a promising system to improve the solubility and sustain the absorption of poorly water-soluble drugs.

Preparation and characterization of pH-independent sustained release tablet containing solid dispersion granules of a poorly water-soluble drug

Sustained release (SR) tablets containing solid dispersions (SD) granules of a poorly water-soluble drug were prepared to investigate the controlled pH-independent release of the drug. Losartan potassium (LST), an anti-hypertensive agent was chosen as a model drug because of its pH-dependent solubility and short elimination half-life. Poloxamer 188 was used as an SD carrier. A free-flowing SD granule was prepared by adsorbing the melt of the drug and poloxamer 188 onto the surface of an adsorbent, Aerosil 300 (fumed silicon dioxide), followed by direct compression with polyethylene oxide (PEO, 5 × 10 6) to obtain an SD-loaded SR (SD-SR) matrix tablet. Differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) revealed partially amorphous structures of the drug in the SD granules. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) images indicated adsorption of SD granules onto the surface of the adsorbent. The SD granules dissolved completely within 10 min, a dissolution rate much higher than that of pure LST. Moreover, pH-independent sustained release of LST from the SD-SR tablet was achieved for 2 h in gastric fluid (pH 1.2) and for 10 h in intestinal fluid (pH 6.8). A combination of SD techniques using surface adsorption and SR concepts is a promising approach to control the release rate of poorly water-soluble drugs in a pH-independent manner.

Stability-enhanced solid dispersion formulation of amorphous raloxifene hydrochloride

To develop a stabilized formulation of amorphous raloxifene hydrochloride (RXF), solid dispersion granules (SDG) of amorphous RXF were prepared by fluidized bed granulation with non-pareil beads, compressed and filmcoated to produce solid dispersion tablets (SDT). Polymorphic changes in RXF were inhibited by SDG formulation. Drug content, impurity, and dissolution profile of SDT revealed that the SDT meets the acceptance criteria, and the content of RXF was maintained over 95% for 5 months at accelerated conditions of 40 °C and 75% R.H. In comparative dissolution study of reference tablet (Evista®) and SDT, the similarity factor (f2) provided evidence for similar dissolution profiles between two formulations. Therefore, we suggest the usefulness of SDT for the development of generic pharmaceuticals containing amorphous RXF.

Design, Optimization, Preparation and Evaluation of Dispersion Granules of Valsartan and Formulation into Tablets

The objective of the present work undertaken was to enhance the solubility and dissolution rate of valsartan a poorly water soluble antihypertensive, by preparation of solid dispersion granules which would additionally allow easy compression into tablets. The dispersion granules were prepared using a hot melt granulation technique which involved preparation of a homogenous dispersion of valsartan in gelucire-50/13 melt, followed by its adsorption on to the surface of aeroperl-300pharma, an inert adsorbent. A two-factor, three-level (32) statistical design was implemented to quantitate the influence of gelucire-50/13 and aeroperl-300pharma on the dissolution profile and flow properties of the dispersion granules, where gelucire-50/13 and aeroperl-300pharma were chosen as independent variables, while dissolution and flow properties were chosen as dependent variables. The dispersion granules were characterized for their in-vitro dissolution rate and flow properties. An appropriate statistical model was arrived at and a significantly enhanced dissolution rate and flow properties were exhibited with the optimized formulation. The formulation was further characterized by FTIR, DSC, XRD and SEM analysis. FTIR spectrum revealed some drug excipient interactions. DSC and XRD data indicated the retention of amorphous form of valsartan. SEM confirmed the homogeneity and surface adsorption of the gelucire-50/13 melt on aeroperl-300pharma leading to enhanced surface area and thus dissolution rate. The tablets of optimized dispersion granules were formulated and evaluated. The in-vitro dissolution rate of these tablets was significantly better in comparison with marketed formulation. In conclusion the statistical model enabled us to understand the effects of formulation variables on the dispersion granules of valsartan.

Development of novel sustained-release system, disintegration-controlled matrix tablet (DCMT) with solid dispersion granules of nilvadipine (II): In vivo evaluation

A novel sustained-release (SR) system, disintegration-controlled matrix tablet (DCMT), was developed for poorly water-soluble drugs. DCMT, consisting of wax and solid dispersion (SD) granules containing a disintegrant, could control the release of nilvadipine (NiD), a model compound, by its disintegration. In the present study, two DCMTs (DCMT-1 and DCMT-2) with different release rates of NiD were orally administered to beagle dogs, and in vivo absorption of NiD from DCMTs was compared with that from immediate-release (IR) tablets. DCMTs successfully sustained the absorption of NiD longer than IR tablets, while they did not decrease the bioavailability of NiD. DCMT-2, providing the slower release of NiD than DCMT-1, prolonged the absorption longer than DCMT-1. In vivo absorption profiles of NiD from DCMTs were significantly correlated with in vitro release profiles, suggesting that the release property from DCMTs would maintain regardless of the change in physiological condition through the gastrointestinal tract. Furthermore, the food intake did not affect the absorption of NiD after oral administration of DCMT-2. The present results strongly indicate that the DCMT system would be a promising SR system, which could improve the solubility and sustain the absorption of poorly water-soluble drugs.