dissolution

The purpose of the present study was to enhance the solubility and dissolution rate of a poorly water soluble drug by solid dispersion technique. Irbesartan was used as a model drug to evaluate its release characteristics from the formulations. Solid dispersions of Irbesartan with PEG 4000 and PEG 6000 were prepared by physical mixing, solvent evaporation and melting techniques in w/w ratios (drug: carrier). Characterization of the solid dispersions was carried out by Differential Scanning Calorimetry (DSC) and Fourier Transform Infra-Red spectroscopy (FTIR). The dissolution profiles of solid dispersions were compared with those of the pure drug. Solid dispersions of Irbesartan with PEG 4000 prepared by solvent evaporation technique at 1:1 ratio showed greater dissolution compared to other formulations. FTIR and DSC studies showed no significant interaction between Irbesartan and the hydrophilic carriers.

The poor aqueous solubility and dissolution rate of API is one of the main challenge in pharmaceutical development. The improvement of solubility and dissolution profiles of these lipophilic drug molecules without altering the molecular structure is a particular challenge for the successful development of pharmaceutical products. Pharmaceutical cocrystals are molecular complexes of an API and one or more cocrystal formers, which are solids at room temperature, interacting through hydrogen bonding, π-stacking or van der Waals forces. A crystalline form of the API is strongly preferred because of their relative ease of isolation, and the physico-chemical stability that the crystalline solid state affords. The vast majority of APIs occur as solids; these include, salts, polymorphs, cocrystals and hydrates/solvates. Cocrystallization as a method of obtaining new forms of Active Pharmaceutical Ingredients (APIs) with improved physicochemical properties like solubility, stability, and melting point has gained much attention in recent years and is a promising alternative to so far employed preparation of salts, hydrates, solvates and other forms. Cocrystallization improves physicochemical properties of drug without affecting their pharmacological properties. There are various methods for preparation of cocrystals like solvent evaporation, solution crystallization, antisolvent addition, kneading etc. The characterization methods includes FTIR, DSC, PXRD, NMR, Raman spectroscopy etc.

In this paper an attempt is made to prepare IPN beads of the drug by taking alginate solution in combination with a polymer (PVA/Kennel powder /Guar gum). The prepared copolymer solution is dropped in to 2% CaCl2. The beads are hardened by cross linking with a common cross-linking agent, glutaraldehyde. The beads are characterized by Fourier transform infra-red spectroscopy and scanning electron microscopy. Additionally quality control tests such as swelling index, bead water uptake, entrapment efficiency and drug release studies are performed. The extent of cross-linking is studied in terms of the size and release characteristics of the beads. Most of the formulations indicated erosion based release pattern. The size of the beads ranged from 250 to 400 µm. The entrapment efficiency of the formulation ranged from 73.6% to 94.50%.  

In the last decade, poorly soluble drugs have been an area of concern for all the researchers in the field of pharmacy. A number of researches have been carried out to enhance the solubility and dissolution properties of such drugs. This study deals with a comprehensive review of liquisolid technique carried out mainly for biopharmaceutical classification system (BCS) class II & IV drugs. These drugs are having problems of poor solubility, dissolution and thus poor bioavailability. Various studies conducted on a number of drugs so far, have been reviewed. A variety of techniques such as micronization, salt formation, complexation, solid solutions, and liquisolid technique etc. have been used to overcome such problems. It has been observed that liquisolid technique is the most promising way for solubility and dissolution enhancement of such drugs. It can be concluded that liquisolid technique results in increased solubility, dissolution and thus bioavailability.

Poor water solubility has always been one of the most fundamental problem in drug delivery. It is estimated that around 40% of drugs in the pipeline cannot be delivered through the preferred route or in some cases, at all owing to poor water solubility. Different methods available to improve solubility and dissolution include salt formation, micronization, chemical modification, pH adjustment, solid dispersion, complexation, hydrotropy, micellar solubilisation. Among these, solid dispersions have proved to be a successful strategy for enhancing aqueous solubility of drugs. The present review focus on different solid dispersion techniques used for the improvement of solubility and dissolution rate of poorly water soluble drugs, carriers used, advantages and limitations of each technique.

This study evaluated the dissolution behaviour of a novel amorphous form (Form A) and the commercially preferred crystalline form (Form I) of efavirenz. Generally, amorphous forms tend to achieve a greater extent and rate of dissolution compared to their crystalline counterparts. The results showed that the dissolution of Form A to be significantly lower than that of Form I due to agglomeration. Factors which contributed to the agglomeration behaviour of Form A include: high surface free energy, a lower degree of wetting, and the low glass transition temperature of Form A which caused the sample to convert to the rubber phase which is stickier. The agglomeration increased the relative particle size thereby reducing the exposed surface area of Form A; ultimately reducing the rate and extent of dissolution. The dissolution behaviour of Form A was found to be dependent on sample size and surfactant (SLS) concentration. Scanning Electron Microscopy (SEM) was employed to investigate surface area properties which provided information supporting the powder dissolution results. The solubility and intrinsic behaviour of the two forms were found to be comparable. Upon further investigation it was found that Form A undergoes phase mediated transformation into Form I during the solubility and dissolution experiments and that this too contributed to the apparent dissolution and solubility behaviour of Form A.  It was found the nucleation rate of Form A was potentiated by higher SLS content in the dissolution medium. Keywords: polymorph, amorph, dissolution, solubility, efavirenz.

  In the present work the approach of forced degradation study was successfully applied for the development of stability-indicating assay method for determination of Thiocolchicoside in the presence of its degradation products.  The RP-HPLC separation was carried out on Shimadzu® -HPLC 1100 series using a Phenomenex ODS 5µ C18 column (250×4.6mm) with mobile phase comprising of Acetonitrile: Phosphate Buffer (70:30) pH 3.5 v/v at flow rate of 1.0mL/min and UV detection at 260.0 nm. In stress testing a drug substance or the drug product is exposed to an environment vigorous than the normal i.e. at high temperature, high humidity over the period of time called accelerated stability conditions. The drug was subjected to Solid state analysis which includes Humidity studies (40°C/75% RH), photochemical studies (UV light and sunlight exposure) and Thermal studies to apply stress conditions. The method was validated as per ICH guidelines for accuracy, precision, linearity and range, ruggedness and robustness. The linearity of the proposed method was investigated in the range of 80-120% of label claim; the correlation coefficient for Thiocolchicoside was found to be 0.999. The proposed method was found to be simple, specific, linear and rugged and can be used for routine quality control.