The matrix tablets of cinnarizine and nimodipine were prepared with varying ratio of Carbopol- 971P and co-excipients of varying hydrophilicity (i.e. dicalcium phosphate and spray dried lactose) by direct compression and wet granulation using alcoholic mucilage. The prepared tablets were evaluated for weight variation, hardness and friability. The influence of concentration of the matrix forming material and co-excipients on the release rate of the drug was studied. The release rate of Cinnarizine (more soluble drug) from tablets followed diffusion controlled mechanism whereas for nimodipine (less soluble drug), the drug release followed case-II or super case- II transport mechanism based on Korsmeyer- Peppas equation. The results indicated that the drug release from matrix tablets was increases with increase in hydrophilicity of drug and coexcipients. The release of drug also increased with thermal treatment and decreasing polymer concentration.

The objective of present study was to develop colon targeted drug delivery using bacterially triggered approach through oral route. Valdecoxib (COX-2 inhibitor) was chosen as a model drug in order to target it to colon which may prove useful in inflammatory bowel disease and related disorders. Matrix tablets of Valdecoxib were prepared by wet granulation technique utilizing different ratio of Guar gum and Sodium starch glycholate. The prepared matrix tablets were evaluated for uniformity of weight, uniformity of content, hardness and in vitro dissolution study in simulated gastric and intestinal fluid (Phosphate Buffer pH-1.2, pH-6.8 and pH-7.4), followed by Dissolution study in bio-relevant dissolution media Phosphate Buffer (pH-6.8) containing rat caecal content. The results revealed that the formulated batch had released lesser quantity of drug at pH 1.2 and pH 7.4 in 2 hors whereas in biorelevent dissolution media containing rat caecal content it released significantly higher amount of drug which was also significantly higher than the dissolution media of same pH without caecal content (microflora) and it was concluded that guar gum can be used as a potential carrier for targeting drugs to colon.

Ibuprofen (IBU) suffers from the general side effects of NSAIDs owing to local and systemic action. The study aimed to retard the adverse effects of gastrointestinal origin. A macromolecular prodrug of IBU was synthesized by coupling the drug to 2-hydroxypropyl methacrylate (HEMA) to get a monomeric drug conjugate which was then polymerized to get polymeric prodrug. Purified synthesized prodrug was characterized by m.p, TLC, UV, FTIR, NMR and MS. The prodrug was evaluated for its in-vitro drug release behavior in buffers of pH 1.2 and 7.4 mimicking the upper and lower GIT respectively. The results showed that the drug release from the polymeric backbone takes place in a sustained manner over a period of 12 h and the amount of drug released was comparatively higher at pH 7.4 indicating that the drug release should takes place predominantly at the alkaline environment of the lower GIT rather than at the acidic environment of the upper GIT. The in-vivo release studies in rabbits after oral administration of IBU conjugate revealed sustained release characteristics within the prodrug treated animals. This study suggested that after oral administration, the drug –polymer conjugate can release IBU for prolonged periods and predominantly in the lower GIT in a site specific manner, thus reducing the direct contact of the drug to the gastric mucosa and hence the GIT complications.

Clinical studies of lisinopril delivery through iontophoresis are highly desired for better controls over transdermal drug flux. Therefore, investigations were carried out to ascertain the relative importance of the various factor for iontophoretic transport using an ionizable drug lisinopril, which has four pKa values 2.4, 4.0 (for amino group) and 6.7, 7.0 (for carboxylic group). Ionization of lisinopril varies with pH, hence rate and extent of transport across the skin can be enhanced, controlled and manipulated by the application of factors like anodal and cathodal current at varied pH of donor solution and current densities. To determine these parameters, experiments were performed and data were collected at 3.0, 4.0 and 7.4 pH using 4 mg/ml drug concentration and 0.1 mA/cm2 current density for 10 hours. After establishing the pH for optimum transport of drug, effect of current density (0.1, 0.2, 0.3 and 0.4 mA/cm2) on the transport of drug (keeping drug concentration constant) were investigated. Passive diffusion of lisinopril was maximal at pH 3.0, when unionized form of drug was 45%. Anodal iontophoresis was most effective (significant result, p < 0.05) in transport of drug across skin as compared to cathodal iontophoresis at pH 3.0. While at pH 4.0, cathodal iontophoretic transport of lisinopril across rat skin was highly effective (Student‘t’ test, p < 0.05) compared to anodal iontophoresis. The effect of current density on steady state flux of lisinopril during cathodal iontophoresis at 7.4 pH was 1.33 ± 1.12 and 24.8 ± 3.1 µg/cm2/h at 0.0 under passive diffusion and 4 mA/cm2, respectively. Thus, flux was enhanced nearly 18.6 times during anodal iontophoresis as compared to passive diffusion. For cathodal flux at pH 3.0 on similar iontophoretic treatment showed enhancement nearly 4 times.