Sustained release tablet of theophylline by hot melt wax coating technology

Coating is one of the effective method used for sustaining the release of dosage form. There are various hydrophilic and hydrophilic polymers which are use to sustain the drug release. Waxes are one of the material which can be use to coat the drug in order to control the release. Coating with waxes can be achieved by dissolving it in suitable solvent or by hot melt wax coating. Hot melt coating technique defined as the application of fine layer of coating material in molten state over the substrate. Hot melt coating technique is widely used to coat granules, pellets and tablets in order to sustained the drug release, mask the bitter taste of drug, improve stability etc. Hot melt wax coatings have various advantages over wax solution coating. Toxicity of the organic solvent residues and the influence of environmental protection are major problems associated with solvent coating. The main goal of this study was to study the effect of different coating technique i.e. pan spray method and pan pour method on release pattern of theophylline and also to study the effect of different pore former like sodium laurel sulphate (SLS) and hydroxyl propyl methyl cellulose (HPMC) on release pattern. It was found that pan spray technique is the best technique to control the release due to uniform film formation, while pan pour method showed variation in release of drug from same batch this was due to non uniform coating of tablets and very low coating efficiency. If we compare the effect of pore former it was found that release of drug can be controlled by using suitable concentration of pore former while faster release was seen when SLS was used as a pore former in lower concentration than HPMC.

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Formulation, development and evaluation of patient friendly dosage forms of metformin, Part-III: Soluble effervescent tablets

Metformin hydrochloride is an orally administered antihyperglycemic agent, used in the management of non-insulin-dependant (type-2) diabetes mellitus. Difficulty in swallowing (dysphagia) is common among all age groups, especially in elderly and pediatrics. Unfortunately, a high percentage of patients suffering from type-2 diabetes are elderly people showing dysphagia. The above problem becomes even more severe due to high dose (500-1000 mg) and need for daily intake of metformin. Thus, the above titled work was undertaken to provide patient friendly dosage form. Not only metformin is poorly compressible (Carr’s index 37), but effervescent ingredients are also poorly compressible so, method of wet granulation was used for preparation of tablets using absolute alcohol as binder. Metformin effervescent tablets were prepared using citric acid (CA), tartaric acid (TA), and treated sodium bicarbonate (heating at 120°C for 30 min), glycine, talc, sucralose, and mango flavor. Controlled heating of sodium bicarbonate formed a sheath or desiccant skin of sodium carbonate on bicarbonate nucleus leading to surface passivation which prevents onset effervescent reaction in presence of moisture leading to stability. Of all combinations, CA and TA in the molar ratio 1:2 was found to be most stable as higher amount of least hygroscopic TA protects hygroscopic CA from the attack of moisture. Also, it was found that using treated sodium bicarbonate in stoichiometric ratio gave substantially stable effervescent tablets on short term stability study (room temperature and humidity and 75% relative humidity (RH) and room temperature) as sodium carbonate preferentially absorbs moisture. All the ingredients selected were water soluble.

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Formulation, development and evaluation of patient friendly dosage forms of metformin, Part-II: Oral soft gel

Dionvenience of administration and patient compliance are gaining significant importance in the design of dosage forms. Metformin hydrochloride is an orally administered antihyperglycemic agent, used in the management of non-insulin-dependant (type-2) diabetes mellitus. Difficulty in swallowing (dysphagia) is common among all age groups, especially in elderly and pediatrics. Unfortunately, a high percentage of patients suffering from type-2 diabetes are elderly people showing dysphagia. Persons suffering from dysphagia may get choked when they consume liquid formulation, thus to alleviate such problem liquid formulation of high viscosity was prepared. Formulation of oral soft gel batches of metformin was carried out using hydrophilic polymer gellan gum at concentrations ranging from 0.2-0.4% w/v and sodium citrate at two different concentrations (0.3% and 0.5%). The prepared batches were evaluated for appearance, viscosity, pH, drug content, syneresis, in vitro drug release, and taste masking. The batch with 0.4% w/v gellan gum and 0.5% sodium citrate not only showed 85% drug release at 15 min, but all the desired organoleptic properties. The taste masking was carried out using nonnutritive sugar and flavors. The optimized batch showed substantial stability when subjected to short term stability study (0-8°C and Room temperature). The problem of dose measurement by patients was outweighed as oral medicated gels are to be packed in unit dose container.

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Formulation, development and evaluation of patient friendly dosage forms of metformin, Part-I: Orally disintegrating tablets

Metformin hydrochloride is an orally administered antihyperglycemic agent, used in the management of non-insulin-dependant (type-2) diabetes mellitus. Difficulty in swallowing (dysphagia) is common among all age groups, especially in elderly and pediatrics. Unfortunately, a high percentage of patients suffering from type-2 diabetes are elderly people showing dysphagia. In this study, orally disintegrating tablets were prepared using direct compression and wet granulation method. First, the tablets of metformin were prepared using starch RX1500 and microcrystalline cellulose by direct compression. The tablets showed erosion behavior rather than disintegration. Then lactose was incorporated which created pores to cause burst release of drug. But these tablets did not give good mouth feel. Thus, Pearlitol SD 200 (spray dried mannitol) was used to prepare tablets by wet granulation (10% polyvinylpyrrolidone in Isopropyl alcohol as binder). The optimized batches of tablets (LMCT3 and MP13) not only exhibited desired mouth feel but also disintegration time, in vitro dispersion time, water absorption ratio, and in vitro drug release. All the batches contained 15% starch 1500 and 4% of croscarmellose sodium. The optimized batches prepared by direct compression and wet granulation showed 85% drug release at 4 min and 8 min, respectively. The strong saline and slight bitter taste of the drug was masked using nonnutritive sweetener and flavor.

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A New Approach: Enhancement of solubility of Rofecoxib

The present study is aimed at improving the dissolution of poorly soluble drug, rofecoxib. Rofecoxib, being a drug, basic in nature shows a better solubility in acidic environment. Hence, an attempt was made to provide an acidic microenvironment around the drug molecules by incorporating various freely soluble acidic substances. Addition of such additives provides a dual effect of not only providing an acidic microenvironment but also imparts solubilizing effects due to the free water-soluble nature of the additives used. In the present work, β-cyclodextrin (β-CD) complexes of rofecoxib were prepared and solubilizing additives such as citric acid and ascorbic acid were incorporated in various proportions. Dissolution studies were performed in both HCl buffer (pH 1.2) and phosphate buffer (pH 7.4). The results have shown an enhanced dissolution rate of rofecoxib in both media from beta-cyclodextrin. complex, and a further enhancement of dissolution was found in presence of ascorbic acid as well as citric acid. Differential scanning calorimetery (DSC) and infrared spectroscopy (IR) spectral studies performed on the solid complexes have shown that there is no interaction of the drug with β-CD and the additives. Hence, β-CD enhances the solubility of rofecoxib, and by creating an acidic microenvironment around the drug molecules, solubility of rofecoxib can be enhanced further, which in turn will enhance the absorption of rofecoxib and produce a better pharmacological activity.

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