Secnidazole, a high dose antiprotozoal agent unstable at gastric pH was used as a model compound for deposition onto the adsorbent carriers by two methods namely solvent deposition and physical mixing for duodenal delivery. The drug/adsorbent systems were evaluated for pharmacotechnical properties and characterized by FT-IR, DSC, XRD, SEM and in vitro dissolution testing to investigate the influence of carriers and methods of preparation on in vitro drug release. The solvent deposited secnidazole adsorbates (F4-F6) with high drug loading capacity and better control on dissolution at all time points were subjected to modified release by encapsulating in formaldehyde treated PVP K40 coated capsules. The optimized formulation was able to maintain zero order release with a maximum release of 95.91% at the end of 8 h in contrast to marketed formulation that gave a burst release of 67.89% within 2.5 hours followed by a non zero order release of 87.89% at the end of fifth hour. Thus a formulation of secnidazole accurel adsorbates could be developed that when suitably designed provided controlled duodenal delivery.

A macromolecular prodrug of didanosine (ddI) for oral administration was synthesized and evaluated for in-vitro drug release profile. Didanosine was first coupled to 2-hydroxy ethyl methacrylate (HEMA) through a succinic spacer to form HEMA-Suc-ddI monomeric conjugate which was subsequently polymerized to yield Poly(HEMA-Suc-ddI) conjugate. The structures of the synthesized compounds were characterized by FT-IR, Mass and 1H-NMR spectroscopy. The prodrug was subjected for in-vitro drug release studies in buffers of pH 1.2 and 7.4 mimicking the upper and lower GIT. The results showed that the drug release from the polymeric backbone takes place in a sustained manner over a period of 24 h and the amount of drug released was comparatively higher at pH 7.4 indicating that the drug release takes place predominantly at the alkaline environment of the lower GIT rather than at the acidic environment of the upper GIT. This pH dependent sustained drug release behavior of the prodrug may be capable of reducing the dose limiting toxicities by maintaining the plasma drug level within the therapeutic range and increasing t1/2 of ddI. Moreover, the bioavailability of the drug should be improved as the prodrug releases ddI predominantly in the alkaline environment which will reduce the degradation of ddI in the stomach acid.

The present investigation deals with the formulation of fast disintegrating tablets of Meloxicam that disintegrate in the oral cavity upon contact with saliva and there by improve therapeutic efficacy. Meloxicam is a newer selective COX-1 inhibitor. The tablets were prepared by wet granulation procedure. The influence of superdisintegrants, crosspovidone, croscaremellose sodium on disintegration time, wetting time and water absorption ratio were studied. Tablets were evaluated for weight and thickness variation, disintegration time, drug content, in vitro dissolution, wetting time and water absorption ratio. The in vitro disintegration time of the best fast disintegrating tablets was found to be 18 sec. Tablets containing crospovidone exhibit quick disintegration time than tablets containing croscaremellose sodium. The fast disintegrating tablets of Meloxicam with shorter disintegration time, acceptable taste and sufficient hardness could be prepared using crospovidone and other excipients at optimum concentration

Felodipine which is used in the present study is a dihydropyridine derivative, that is chemically described as ethyl methyl-4-(2, 3-dichlorophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate, widely accepted for its excellent antihypertensive and anti-anginal properties since it is calcium antagonist compound (calcium channel blocker). Felodipine is practically insoluble in water and its dissolution rate is limited by its physicochemical properties. In the present study fast disintegrating tablets of felodipine were prepared by adopting vacuum drying technique to study the effect of different subliming agents with various concentrations on disintegrating time. The powder blend was examined for the pre-compressional parameters. The prepared formulations were evaluated for post-compressional analysis for the parameters like hardness, friability, thickness, wetting time, water absorption ratio, weight variation, in-vitro disintegration time, in- vitro dispersion time, in-vitro dissolution study. Drug compatibility with excipients was checked by FTIR studies. The results obtained showed that quantity of ammonium bicarbonate, urea and menthol significantly affect the response variables (P> 0.05). No chemical interaction between drug and excipients was confirmed by FTIR studies. Stability studies carried out as per ICH guidelines for three months and results revealed that upon storage disintegration time of tablets decreased significantly (P> 0.05). The results concluded that fast disintegrating tablets of felodipine showing enhanced dissolution rate with increasing the concentrations of subliming agents. Among all the formulations A3 and M3 shows the improved dissolution rate which lead to improved bioavailability and effective
therapy by using vacuum drying technique.

Taste is most important organoleptic aspects about the acceptance of oral drugs. Bitter and unpalatable taste is a major problem of certain drugs in formulations. In market, there are numbers of pharmaceutical preparations available in which actives are bitter in taste. The improved palatability in these products has prompted the development of numerous formulations, which improved performance and acceptability. The bitterness of preparation also leads to patient incompliance. So masking of bitterness becomes essential and done by masking the bitter taste of drugs by either decreasing its oral solubility on ingestion or decreasing the amount of drug particles exposed to taste buds thereby reducing the perception of bitter taste. Methods commonly used for taste masking involves various physical and chemical method that prevent the interaction of taste bud with drugs and are based on coatings, solid dispersion system and ion exchange resin, entrapment method and masking of taste buds etc. Taste masking of bitter drugs become necessity in case of oral administration and selection of technology depends upon the bitterness of drugs and their compatibility with taste masking agents that does not affect the bioavailability of drug