solid dispersion

In pharmaceutical industry the major problem of dosage form development is low aqueous solubility. In present review the particle engineering concept and solubility, permeability approaches design and method used in improvement of particle size. The different methods are used in particle engineering like supercritical fluid technology, controlled precipitation, and mechanical technique, evaporation precipitation to aqueous solution, freezing technique, and sonication technology etc. discussed. The improvements of aqueous solubility need to be formulation development for dosage form very essential. The BCS class II drugs modified to soluble form for need of bioavailability of drugs. The solid dispersion method with a different carrier improves the solubility.

There are various techniques to control the release rate of the drugs, among which controlling dissolution rate is most popular due to its success and low cost. The use of sustained release dosage forms is increasing in treatment of acute and chronic diseases as they maintain the concentration of drug in plasma above minimum effective concentration and below the minimum toxic level for extended period of time. Thus, sustained drug delivery results in optimum drug therapy with reduced frequency of dosing and side effects. The objectives of the present investigation were to prepare granules of aceclofenac with different polymers and polymer blends by solid dispersion technique and investigate the different tablet evaluation parameters. Solid dispersions were prepared by solvent evaporation technique by using different polymers (Hydroxypropyl methyl cellulose - K4M, Ethyl cellulose, and Eudragit RS-100).Solid state and drug polymer interactions were studied by Fourier transform infra red spectroscopy, Differential scanning calorimetry, X-ray powder diffraction. The pharmaceutical performance was studied by in-vitro dissolution experiments.  Studies for the kinetics of the drug release from tablets showed a good fit to zero order kinetics indicating better controlled release of the drug. Significant effect was observed with polymer, concentration of polymer mixture on similarity factor. In stability study there was no significant change in the tablet properties after exposure to 40 ± 2 0C and 75 ± 5% RH for a period of 3 months.

Enhancement of the solubility, dissolution and bioavailability of the drugs is the challenging task for the research sector. As many of the solubility enhancement techniques are available to achieve the desired goal, but the older techniques don’t show the expected results for solubility enhancement and bioavailability as well, and they are unstable also some time.  But today the scenario is different because the novel techniques of solubility enhancement are available, such as hydrotropy, supercritical fluid process, sonocrystallisation, inclusion complex system, spray drying, microwave assisted techniques, etc. this novel techniques have the ability to give the reproducible results for solubility enhancement in pharmaceutical product development.  present review article deals with the different techniques for the solubility enhancement of the poorly soluble drug candidates.

Tablet is the most popular dosage form of all existing dosage forms , but in some cases due to the large size of dosage forms, in case of uncooperative, pediatric and dysphasia patients, it may create  problems, to overcome this , a new form of dosage form is developed, which is known as fast dissolving tablets or mouth dissolving tablets. These dosage forms are also used to attain instant higher concentration of drug in body for immediate actions. Gliclazide is an oral antihyperglycemic agent used for the treatment of non-insulin-dependent diabetes mellitus (NIDDM). Fenugreek seed powder was added to this formuation because of  its various pharmacological benefits as well as its self disintegrating property. Mouth dissolving tablets were prepared using direct compression method .Formulations were optimized to develop tablets having minimum possible disintegration time. Tablets were evaluated for hardness, weight variation, friability, wetting time, disintegration time and stability. The main objective of the present research is formulation and evaluation  of mouth dissolving tablets of gliclazide which is an antidiabetic drug ,containing fenugreek seed powder as disintegrating agent.

A drug should be present in dissolved or solublized state before producing its therapeutic effect however in current market more than 40% drugs are poorly soluble in water. Such drugs exhibit poor dissolution rate and slow absorption throughout the gastrointestinal tract which leads to irregular bioavailability. Thus various techniques has been adopted for solubility and dissolution enhancement of poor water soluble drugs thereby bioavailability. Solubility plays an important role in achieving the desired plasma drug concentration. In this review article various techniques like solid dispersion, SLNs, SEDDS, dried emulsion were discussed for solubility and dissolution rate improvement of BCS class II anti hyperlipidemic drug Simvastatin. Amongst various method described in this review, solid dispersion was found to be most used technique by researcher as it provide ease in preparation and efficiency in terms of resolving the solubility and dissolution problems associated with Simvastatin.

  The aim of the present work was to improve the solubility and dissolution rate of simvastatin, a drug used for the treatment of hyperlipidemia. Simvastatin is a selective competitive inhibitor of HMG CoA reductase. However its absolute bioavailability is 5 %. To increase the solubility of drug solid dispersion was prepared. Solid dispersion preliminary solubility analysis was carried out for the selection of carriers and solid dispersion was prepared with PEG 4000 and PVP-K30. These solid dispersions were analyzed for the solubility and In-vitro dissolution profile, solid dispersion of drug with PEG 4000 had shown enhanced solubility with improved dissolution rate. Further FTIR, X-Ray studies were carried out. Solid dispersion prepared with PEG 4000 in 1:5 ratio shows the presence of amorphous form confirmed by the characterization study .The study also shows the that dissolution rate of Simvastatin can be enhanced to considerable extent by solid dispersion technique with PEG4000. Key words: Hyperlipidemia, solid dispersion, PEG4000, PVP-K30.