The purpose of this research was to prepare a floating drug delivery system of diltiazem hydrochloride (DTZ). Floating matrix tablets of DTZ were developed to prolong gastric residence time and increase its bioavailability. Rapid gastrointestinal transit could result in incomplete drug release from the drug delivery system above the absorption zone leading to diminished efficacy of the administered dose. The tablets were prepared by direct compression technique, using polymers such as hydroxypropylmethylcellulose (HPMC, Methocel K100M CR), Compritol 888 ATO, alone or in combination and other standard excipients. Sodium bicarbonate was incorporated as a gas-generating agent. The effects of sodium bicarbonate and succinic acid on drug release profile and floating properties were investigated. A 3(2) factorial design was applied to systematically optimize the drug release profile. The amounts of Methocel K100M CR (X1) and Compritol 888 ATO (X2) were selected as independent variables. The time required for 50% (t50) and 85% (t85) drug dissolution were selected as dependent variables. The results of factorial design indicated that a high level of both Methocel K100M CR (X1) and Compritol 888 ATO (X2) favors the preparation of floating controlled release of DTZ tablets. Comparable release profiles between the commercial product and the designed system were obtained. The linear regression analysis and model fitting showed that all these formulations followed Korsmeyer and Peppas model, which had a higher value of correlation coefficient (r). While tablet hardness had little or no effect on the release kinetics and was found to be a determining factor with regards to the buoyancy of the tablets.

The use of microemulsions as drug delivery vehicle has been an exciting and attractive area of research because of its many potential and extraordinary benefits. Microemulsions offer an interesting and potentially quite powerful alternative carrier system for drug delivery because of their high solubilization capacity, transparency, thermodynamic stability, ease of preparation, and high diffusion and absorption rates when compared to solvent without the surfactant system. The oral efficacy of microemulsion has already been proved by cyclosporine formulation (Neoral), but apart from oral route, microemulsions for other routes like dermal, transdermal, ocular, vaginal, rectal, buccal, periodontal, parenteral, and nasal delivery routes have also been developed. The present review focuses on various applications of microemulsions through different above mentioned routes and also gives idea about new application of micro emulsion as oral solid dosage form, as microreactors and as blood substitute.

Applied chemistry Z 0300 Applications of Microemulsion-Based Drug Delivery System -[53 refs.]. -(JADHAV, K. R.; SHAIKH, I. M.; AMBADE, K. W.; KADAM, V. J.; Current Drug Delivery 3 (2006) 3, 267-273; Dep. Pharm., Bharati Vidyapeeth Coll. Pharm., Mumbai 400 614, India; Eng.) -Lindner 37-269

The purpose of the present study was to investigate the microemulsion formulations for topical delivery of Flurbiprofen (FP) in order to by pass its gastrointestinal adverse effects. The pseudoternary phase diagrams were developed and various microemulsion formulations were prepared using Isopropyl Myristate (IPM), Ethyl Oleate (EO) as oils, Aerosol OT as surfactant and Sorbitan Monooleate as cosurfactant. The transdermal permeability of flurbiprofen from microemulsions containing IPM and EO as two different oil phases was analyzed using Keshary-Chien diffusion cell through excised rat skin. Flurbiprofen showed higher in vitro permeation from IPM as compared to that of from EO microemulsion. Thus microemulsion containing IPM as oil phase were selected for optimization. The optimization was carried out using 2 3 factorial design. The optimized formula was then subjected to in vivo anti-inflammatory study and the performance of flurbiprofen from optimized formulation was compared with that of gel cream. Flurbiprofen from optimized microemulsion formulation was found to be more effective as compared to gel cream in inhibiting the caragenan induced rat paw edema at all time intervals. Histopathological investigation of rat skin revealed the safety of microemulsion formulation for topical use. Thus the present study indicates that, microemulsion can be a promising vehicle for the topical delivery of flurbiprofen. Methods In Vitro Inherent Flux Study of a DrugThe inherent flux of flurbiprofen was determined using the Keshary-Chien type diffusion cells. Full thickness abdominal skin of albino rats (125-150 g) was used. The dermal surface of skin was carefully cleaned to remove subcutaneous tissues and fats without damaging the epidermal surface.The Keshary-Chien diffusion cell assembly consisted of donor and receptor compartments. The diffusion cell has a capacity of 20 Formulation and Evaluation of Flurbiprofen Microemulsion