Hot-Melt Extrusion: An Emerging Technique for Solubility Enhancement of Poorly Water-Soluble Drugs.

The solubility of the drug is a significant aspect to be considered during manufacturing of pharmaceutical products. Poor aqueous solubility of drugs imparts depleted bioavailability. In this regard, several techniques are available for enhancing drug solubility or dissolution. However, only few of them are scalable and industrially applicable. Hot-melt extrusion (HME) is one such technique that has been widely used in the industry. It is a single-step, continuous manufacturing, and scalable method that has proved successful in improving the solubility of poorly soluble drugs. This review highlights the numerous pharmaceutical applications of HME, such as formulations of sterile implants, taste masking of unpleasant drugs, cocrystallization, salt formation, sustained and controlled release formulations, etc. It also describes various hydrophilic and hydrophobic carriers utilized in HME. This review also briefly discusses the recent advances in HME and gives an update on the currently available marketed products. The opportunities and challenges in future development of pharmaceutical products by HME technique are also discussed.

Formulation and development of oral dry suspension using taste masked Ornidazole particles prepared using Kollicoat(®) Smartseal 30 D.

The purpose of this work was to taste mask highly bitter active, Ornidazole by means of particle coating. The aim of the work was further extended into formulating these coated particles into an acceptable oral dosage form such as dry suspension. Ornidazole drug particles were coated using Kollicoat(®) Smartseal 30 D as a taste masking polymer. Kollicoat(®) Smartseal 30 D is a methyl methacrylate - diethylaminoethyl methacrylate copolymer (6:4). Successful taste masking was achieved for Ornidazole with both top spray and bottom spray techniques using fluid bed processor. Effective taste masking was achieved at a weight gain of 50% w/w and 40% w/w for bottom and top spray techniques respectively without having a significant effect on the release pattern. A taste masked dry suspension was prepared with around 80% w/w coated Ornidazole particles and pH was maintained around 7-8. The suspension prepared with these coated Ornidazole particles, which were maintained in the alkaline pH was found to be stable for 7 days without affecting the taste. The bitter taste intensity was evaluated using volunteers by comparison of test samples with standard solutions containing Ornidazole at various concentrations. Thus, Kollicoat(®) Smartseal 30 D was found to be an effective polymer for taste masking of a bitter active like Ornidazole. The formulation development of taste masked dry suspensions was only possible due to unique properties possessed by Kollicoat(®) Smartseal 30 D.

Designing, optimisation & characterization of sustained release matrix pellets prepared by extrusion spheronization containing mixture of proteolytic enzymes.

A method for developing sustained release multiple unit dosage form consisting of pellets of a proteolytic enzyme blend using extrusion spheronization as a process is demonstrated in this paper. Effect of Cellulose and Methacrylate based polymers and plasticizers on stability of the enzyme blend are determined. The effect of type & concentration of the sustained release polymer, spheronization rpm and plasticizer on the yield & sphericity of pellets is studied. The results indicated that the SR pellets could be formulated for this enzyme blend using both HPMC K15 and EUDRAGIT RSPO. The best rpm for spheronization turned out to be 1200 rpm. Use of plasticizer improved yield and sphericity. Triethyl citrate was better over polyethylene glycol 400 and EUDRAGIT RSPO was better over HPMC K15 with respect to yield and sphericity of pellets. The pellets could be suitably enteric coated for protection of enzyme blend in lower pH of GIT. The in vitro release profile indicated release extension could be extended up to 12 hours in intestinal condition postulating to an acceptable bioavailablity in vivo.

Evaluation of Sterculia foetida gum as controlled release excipient.

The purpose of the research was to evaluate Sterculia foetida gum as a hydrophilic matrix polymer for controlled release preparation. For evaluation as a matrix polymer; characterization of Sterculia foetida gum was done. Viscosity, pH, scanning electronmicrographs were determined. Different formulation aspects considered were: gum concentration (10-40%), particle size (75-420 microm) and type of fillers and those for dissolution studies; pH, and stirring speed were considered. Tablets prepared with Sterculia foetida gum were compared with tablets prepared with Hydroxymethylcellulose K15M. The release rate profiles were evaluated through different kinetic equations: zero-order, first-order, Higuchi, Hixon-Crowell and Korsemeyer and Peppas models. The scanning electronmicrographs showed that the gum particles were somewhat triangular. The viscosity of 1% solution was found to be 950 centipoise and pH was in range of 4-5. Suitable matrix release profile could be obtained at 40% gum concentration. Higher sustained release profiles were obtained for Sterculia foetida gum particles in size range of 76-125 microm. Notable influences were obtained for type of fillers. Significant differences were also observed with rotational speed and dissolution media pH. The in vitro release profiles indicated that tablets prepared from Sterculia foetida gum had higher retarding capacity than tablets prepared with Hydroxymethylcellulose K15M prepared tablets. The differential scanning calorimetry results indicated that there are no interactions of Sterculia foetida gum with diltiazem hydrochloride. It was observed that release of the drug followed through surface erosion and anomalous diffusion. Thus, it could be concluded that Sterculia foetida gum could be used a controlled release matrix polymer.

Sintering of wax for controlling release from pellets.

The purpose of the present study was to investigate incorporation of hydrophobic (ie, waxy) material into pellets using a thermal sintering technique and to evaluate the pellets in vitro for controlled release. Pellets prepared by extrusion-spheronization technology were formulated with a water-soluble drug, microcrystalline cellulose, and carnauba wax. Powdered carnauba wax (4%-20%) prepared by grinding or by emulsification was studied with an attempt to retard the drug release. The inclusion of ground or emulsified carnauba wax did not sustain the release of theophylline for more than 3 hours. Matrix pellets of theophylline prepared with various concentrations of carnauba wax were sintered thermally at various times and temperatures. In vitro drug release profiles indicated an increase in drug release retardation with increasing carnauba wax concentration. Pellets prepared with ground wax showed a higher standard deviation than did those prepared with emulsified wax. There was incomplete release at the end of 12 hours for pellets prepared with 20% ground or emulsified wax. The sintering temperature and duration were optimized to allow for a sustained release lasting at least 12 hours. The optimized temperature and duration were found to be 100 degrees C and 140 seconds, respectively. The sintered pellets had a higher hydrophobicity than did the unsintered pellets. Scanning electron micrographs indicated that the carnauba wax moved internally, thereby increasing the surface area of wax within the pellets.