Percolation theory is a statistical theory applied to explain behaviour of disordered systems. It considers a system to be composed of an infinite lattice. Random site, random bond and site-bond percolation types are commonly observed. The article explains the concept of percolation theory and types. Leuenberger started the application of this concept in the field of pharmacy. Its applications in powder technology, sustained release matrix systems and emulsions are discussed. The percolation theory will be an important tool in the design of dosage forms.

The field of protected particulates with longer circulation period in vivo is reviewed. Long circulating pharmaceutical carriers are the fastest growing field in the pharmaceutical research, today. Then uptake of particles by reticuloendothelial system poses problem in delivering the drug or active molecule to the appropriate site for a required period of time. This review discusses the possibility of using poly (ethylene glycol) and poly (ethylene oxide) as a coat to prolong the circulation half-life of the microparticulate system in vivo.

Ketorolac tromethamine ocuserts were prepared using different polymers such as HPMC, PVP, MC and EC at various concentrations. The in vitro release of the drug from the formulations was studied using commercial semi permeable membrane. The physico chemical parameters of ocuserts were evaluated. A zero order release formulation 3 (Drug reservoir with 3% HPMC and 4% EC as rate controlling membrane) was subjected to in vivo studies. The expected zero order release for one day was observed in formulation 3 (Drug reservoir with 4% HPMC and 3% EC as rate controlling membrane).

Dispersible tablets of nimesulide (DTN) were formulated using natural substances as disintegrants such as Plantago ovata seed husk, Cassia tora (Sickle senna) and Cassia nodosa in different concentrations. Formulations were evaluated for the standards of dispersible tablets and were compared with marketed products. It was observed that all the formulations were acceptable with the reasonable limits of standards required for dispersible tablets. The study revealed that natural gums used as disintegrants were effective in low (5%) concentration.

Studies on possible antiperoxidative property of glutathione (GLU) and α-tocopherol (TOC) on lipid peroxidation (LP) induced by norethindrone (NE), an antifertility drug, were carried out using goat liver homogenate as the lipid source. The study was aimed at exploring possible potential of the antioxidants to reduce druginduced toxicity that may be mediated through free radical mechan1sm. The degree of peroxidation was quantitated by thiobarbituric acid reactive substance (TEARS) content. The present study revealed that both GLU and TOC could significantly suppress NE-induced lipid peroxidation. Considering lipid peroxidation as a toxicity mediating process, the findings are interesting and provide a scope for further extensive studies on the antioxidants with an aim to increase therapeutic index of the drug.

Dilution method was employed to determine the effect of petroleum ether extract (40-60O) chloroform and methanolic extract of dried leaves of Acalypha indica Linn (Euphorbiaceae) against fungi (Candida albicans) and bacteria (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhosa, Bacillus substilis, Klebsiella pneumoniae). Except the petroleum ether extract, all the extracts exhibited a prominent antimicrobial activity. The methanolic extract was further fractionated into acetone soluble and insoluble parts. Both the parts exhibited prominent antimicrobial activity. The acetone insoluble part exhibited MIC of 0.0040 mg/ml against Staphylococcus aureus and both acetone soluble and insoluble parts exhibited MIC of 0.05 mg/ml against Salmonella typhosa.

The methanolic extract of the rhizome of Aristolochia albida afford aristolochic acid-1 and aristoloside (aristolochic acid-O-glucoside), along with other already isolated compounds. Their structures were characterised by spectroscopic analysis.

The ethanolic extract of the aerial parts of Tephrosia purpurea administered orally at doses of 50,100 and 200 mg/kg, significantly reduced an elevated WBC count in response to antigen challenge in sensitized mice. The extract also significantly inhibited eosinophil infiltration without any significant change in the mononuclear cell popu1ation. The extract failed to alter neutrophil adhesion to nylon fibres. However, it produced a significant inhibitory activity on enzyme lipoxygenase at concentrations of 100 and 200 μg/ml. The inhibitory effect of ethanolic extract of T. purpurea on late-phase allergy could be attributed to the inhibition of leukotriene synthesis.

Thermosensitlve liposomes prepared from synthetic lipids such as dipaltmitoyl phosphatidyl chollne (DPPC), distearoyl phosphatidyl choline (DSPC) and cholesterol (CH) have been tried for local drug release in response to hyperthermia for achieving tumor drug targeting. Herein we report the use of natural lipid, soyabean lipid (SPC) and cholesterol (CH) to prepare thermosensitive liposomes. When liposomes are prepared by reverse evaporation method, It was found that most of the particles are multilamellar small vesicles. In vitro dialysis method was used to study the behavior of the liposomes made from different ratios of SPC and CH after the anticancer drug [2,4 (1H, 3H)-pyrimidine] (5-FU) fluorouracil was entrapped. From the result, it was found that, when the ratio of SPC and cH is proper (8:1), the liposomes made from them release most of the entrapped drug at 40o and the differential scanning calorimetry (DSC) showed that the liquid crystalline transition temperature (Tm) of the liposomes is about 40° too.

The information generated from three dimensional hypothetical receptor surface models built around template molecules has been used to produce highly predictive quantitative structure-activity relationship (QSAR) models for two series of benzimidazole derivatives with antiinflammatory activity. Molecule/receptor model interaction energies on thousands of points on the receptor surface served as input for the calculation of a QSAR relationship. Both electrostatic and van der Waals interaction energies have been used. A genetic algorithm has been used to search significant models. The QSAR models are significant comparable to those produced from using conventional physicochemical descriptors. The receptor surface models generated using high resolution computer graphics are visually intuitive and can be used for activity prediction of new candidate structures.

Thirteen new derivatives of 1,2,4-triazole were synthesized and characterised by elemental analysis, 1H NMR, l3C NMR and IR spectra. Three of these compounds were screened for their antitumor activities using cell lines derived from human solid tumors.

Different transdermal nimesulide gels were prepared using various gel bases, with an objective to formulate suitable transdermal formulation of nimesulide. The polymers selected were sodium alginate, HPMC, NA CMC and methyl cellulose. In vitro release studies of the prepared formulation were performed using dialysis membrane and results indicated that sodium alginate gel showed better release. In vivo antiinflammatory activity was studied in carrageenan-induced rat paw oedema and analgesic activity was studied in acetic acid-induced writhes in rats. Among the prepared formulations, sodium alginate gel showed better antiinflammatory and analgesic activity. Sodium alginate gel found to be more stable when stability study was performed. Sodium alginate gel containing nimesulide was found to be better in all aspects compared to other gel formulations and this was comparable to the marketed gel.

Targeted drug delivery is an effective means in cancer chemotherapy. Nanoparticulation is one of the useful means for targeted drug delivery. In the present investigation a broad spectrum anticancer drug methotrexate is nanoparticulated in a foreign protein bovine serum albumin. The particle size distribution was measured using a transmission electron microscope. Two sets of nanoparticles were prepared by varying Protein: drug ratio. The pattern of drug release from the nanoparticles were observed in pH 7.4 at 37o. A non-fickian type of release was observed from both sets.

Rifampicin and isoniazid (INH) in combination were formulated into liposomes for utilization as a delivery system for optimum therapeutic use in tuberculosis. A modified lipid layer hydration method was employed to prepare liposomes. The formulated liposomes were characterized for size distribution, drug loading and in vitrodrug release studies. The liposomes prepared were in the size range 3.3 to 26.4 mm the mean diameter being 8.64mm. Entrapment efficiencies of 32.06% and 72.42% were obtained for INH and rifampicin in the liposomes respectively. In vitro release study on liposomes indicated 53.42% release for isoniazid and 35.99% for rifampicin. Stability study was carried out at different temperatures and it was found to be stable. In vivo antibacterial activity was determined by agar plate method in albino rats following the administration of liposomal formulation in comparison with drug alone and control. The liposornal drugs exhibited larger zone of inhibition as compared to the free drugs. Thus, it is evident from this study that liposomes could be promising delivery systems for rifampicin and INH with prolonged drug release profiles and better therapeutic effect.

A series of anti-inflammatory 5-phenyl-3H-imidazo(4,5-c) (1,8) naphthyridin-4-(5H)-ones was subjected to quantitative structure activity relationship (QSAR) analysis. The QSAR study showed that the oral antiinflammatory activity, as determined in the carrageenan induced rat paw edema method was highly correlated with thermodynamic (MR) and electronic (Cedensity and Ncharge) parameters. The analysis suggests that lipophilic substituents at third position on the nitrogen atom which increase double bond conjugation within the molecule will enhance the biological activity.

A few 2-phenyl benzopyranones (substituted flavanones) were isolated from the available sources or synthesized by simple base catalyzed condensation of appropriate aryl aldehydes and substituted 2'-hydroxy acetophenones. The effect of these substituted flavanones on contraction evoked by oxytocin, on rat uterus was studied. Of the isolated/synthesized compounds, naringenin showed maximum inhibition of oxytocin-induced contraction of rat uterus.

The ethylacetate extract of flowers of the plant Striga senegalensis Benth after defatting with n-hexane yielded a yellow coloured crystalline compound (from methanol), mp. 350°, characterized as apigenin (4`, 5,7-trihydroxyflavone, C15H10O5) on the basis of spectral analysis (UV, IR, NMR and Mass.).

From the roots of Withania somnifera two new sterols, namely 3-epi-β-sitosterol and 20(21)-dehydrocampesterol, have been isolated along with β-sitosterol and campesterol. The structures of the new phytoconstituents have been established as stigmasta-5-en-3α-ol and (24R)-ergost-5,20(21)-dien-3β-ol.

Quantitative structure-protein binding relationships (QSPBR) have been derived for six non-steroidal antiinflammatory drugs (NSAIDs). Ninety eight topological indices (TIs) for six NSAlDs used in this study were calculated using software Polly 2.3. Variables having statistically significant correlations with association constants were considered to be predictors of the model. Linear relationships between association constants and relevant variables derived using multiple linear regression analysis, were useful in predicting drug binding affinity. The association constants were found to be functions of the degree of complexity (Io), path connectivity indices ( 1X and 3X) and the number of paths, P9. Thus, size and shape of the drug molecule plays an important role in the binding of NSAIDs to serum albumin.

The release of rifampicin from a matrix compressed from a physical mixture of rifampicin, guar gum and sodium lauryl sulfate was investigated. When sodium lauryl sulfate was incorporated in the matrix, the release of rifampicin was found to be linearly related to the square root of time, however, the release depended on the concentration of the sodium lauryl sulfate. As the concentration of sodium lauryl sulfate Increased upto 15%, the release progressively slowed to a minimum, which could be due to the formation of a poorly soluble complex. As the concentration increased further, the release increased as the complex was micellarly solubilized.