Celecoxib (4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]-benzenesulfonamide, is a specific cyclooxygenase-2 (COX-2) inhibitor with no inhibition of cyclooxygenase-1 at therapeutic doses. It is being used successfully for the treatment of rheumatoid arthritis, osteoarthritis, acute pain, familial adenomatous polyposis and primary dysmenorrhea. 1,2) Celecoxib also demonstrated significant chemopreventive activity in colon carcinogenesis, ultraviolet B radiation (UVB) induced skin cancer and breast cancer. [3][4][5] Celecoxib is weakly acidic (pK a is 11.1) and hydrophobic (Log P is 3.5) and its low aqueous solubility (3-7 mg/ml) contributes to high variability in absorption after oral administration. 6)The molecule exists in three polymorphic forms and its solid-state interconversion between the forms at ordinary temperatures has not been observed. It is isolated as agglomerates of long needle-shaped crystals, which exhibit cohesiveness, low bulk density and compressibility, and poor flow properties that impart complications in it's processing into solid dosage forms.7) According to biopharmaceutical classification system, celecoxib is classified as a low solubility and high permeability drug. 6) Therefore, the particle size of celecoxib influences the content uniformity, dissolution and bioavailability of the product. The t max of celecoxib is about three hours after oral administration. Rapid onset of action is necessary to provide fast pain relief in the treatment of acute pain. Therefore, it is necessary to enhance the aqueous solubility and dissolution rate of celecoxib to obtain faster onset of action, to minimize the variability in absorption and improve its overall oral bioavailability. This can be achieved by formulating the drug in lipid-based systems.Among the lipid-based systems, self-microemulsifying drug delivery system (SMEDDS) is a promising technology to improve the rate and extent of the absorption of poorly water-soluble drugs. [8][9][10][11][12][13][14][15] The clinical usefulness of the SMEDDS is evident from the commercially available formulations containing cyclosporin A, ritonavir and Saquinavir. 16,17) SMEDDS are comprised of mixture of drug, oil, surfactant(s) and/or co-solvents which form fine oil in water and/or water in oil microemulsions upon dilution with aqueous medium or in vivo administration. SMEDDS enhances the bioavailability of poorly water-soluble drugs through solubilization in the excipient matrix or interface and dispersion in the gastrointestinal tract. Relatively small size of the dispersed oil droplets in nanometer range and very high surface area to volume ratio are advantages of the microemulsion. These characteristics result in faster drug release from microemulsion in a reproducible manner, which can be designed further to make the release characteristics independent of the gastro intestinal physiology and the fed/fasted state of the patient. 8,[18][19][20] In this study, we have developed an optimized formulation using a self-microemulsifying system in...

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Three types of alkaloidal constituents, viz., beta-phenethylamines, quinazolines and carboxylated tryptamines, in addition to choline and betaine have been isolated from Sida acuta Burm., S. humilis Willd., S. rhombifolia L., and S. spinosa L. and characterized by their physical and spectral properties, and by chemical transformations. The qualitative and quantitative variations in the alkaloidal constituents of roots and aerial portions at different stages of growth were also noted. Elaboration of the quinazoline alkaloids seems to be a characteristic feature of this genus. The favourable combination of sympathomimetic amines and vasicinone in these species would account for their major therapeutic uses in the Indian system of medicine.

The purpose of this research was to prepare a pseudolatex transdermal delivery system for terbutaline sulfate and to evaluate the effect of pH and organic ester penetration enhancers on permeation kinetics of terbutaline sulfate through mice abdominal skin and human cadaver skin. An increase in the permeation flux by increasing pH was observed. The distribution coefficient of terbutaline sulfate between 1-octanol and buffers of different pH values was also pH-dependent. Furthermore, the change of the permeability coefficient with pH correlated well with the distribution coefficient by a 2-degree polynomial equation. The permeation profile and related kinetic parameters of terbutaline sulfate was determined in presence of 3 estertype permeation enhancers incorporated in the films, viz methyl laureate, isopropyl lanolate, and isopropyl myristate. Among the 3, the more pronounced enhancing effect was obtained with isopropyl myristate, regarding the permeation flux, permeability coefficient, and diffusion coefficient. This was attributed to solubility parameter of isopropyl myristate being closer to the solubility parameter of human skin, and such a pronounced enhancing effect was probably caused by its passage across the skin barrier through the lipid pathway.