Volume 63 (2013): Issue 1 (March 2013)

In the present work, interaction of the strategic starting material, methyl 2-isothiocyanatobenzoate (1), with sulfa drugs resulted in the formation of methyl 2-[3-(4-(N-substituted sulfamoyl)phenyl)thioureido] benzoates 2-5, which upon reaction with hydrazine hydrate afforded N-amino derivatives 6-9. Triazoloquinazoline derivatives 10-18 were obtained via reaction of compounds 6-8 with aromatic aldehydes. Also, the reaction of compound 8 with formic acid gave the corresponding triazoloquinazoline derivative 19. Triazinoquinazoline derivatives 22, 23 were obtained via reaction of N-amino derivatives 6 or 8 with ethyl chloroacetate. Interaction of 6 with diethyloxalate yielded triazoloquinazoline 26. The synthesized compounds were screened for their in vitro antimicrobial activities and some of them exhibited promising antibacterial activity compared to ampicillin as positive control. Compounds that revealed significant activity are able to satisfy effectively the proposed pharmacophore geometry.

In the present study, a series of benzothiazol derivatives 3a-l containing pyrazolo[3,4-d]pyrimidine moiety at the second position were synthesized and characterized by analytical and spectral data. The compounds were tested for their in vitro antimicrobial activity. Compounds 1-(1,3-benzothiazol-2- yl)-3-methyl-4-phenyl-1H-pyrazolo[3,4-d]pyrimidine (3a), 1- (1,3-benzothiazol-2-yl)-4-(4-chlorophenyl)-3-methyl-1H-pyrazolo[ 3,4-d]pyrimidine (3d) and 1-(1,3-benzothiazol-2-yl)- 3-methyl-4-substituted phenyl-1H-pyrazolo[3,4-d]pyrimidines (3h-j) showed significant inhibitory activity against P. aeruginosa whereas compounds 1-(1,3-benzothiazol-2-yl)-4- (2-chlorophenyl)-3-methyl-1H-pyrazolo[3,4-d]pyrimidine (3b), 2-[1-(1,3-benzothiazol-2-yl)-3-methyl-1H-pyrazolo[3,4-d]pyrimidin- 4-yl]phenol (3e), 1-(1,3-benzothiazol-2-yl)-4-(3,4-dimethoxyphenyl)- 3-methyl-1H-pyrazolo[3,4-d]pyrimidine (3h), 4-[1-(1,3-benzothiazol-2-yl)-3-methyl-1H-pyrazolo[3,4-d]pyri midin-4-yl]-N,N-dimethylaniline (3j) and 1-(1,3-benzothiazol- 2-yl)-3-methyl-4-[2-phenylvinyl]-1H-pyrazolo[3,4-d]pyrimidine (3k) were found to be active against C. albicans. Some of these synthesized compounds were evaluated for their in vivo acute toxicity, analgesic, anti-inflammatory, and ulcerogenic actions. The tested compound 4-[1-(1,3-benzothiazol- 2-yl)-3-methyl-1H-pyrazolo[3,4-d]pyrimidin-4-yl]-N, N-dimethylaniline (3j) exhibited maximum analgesic and anti-inflammatory activities. Compounds 1-(1,3-benzothiazol- -2-yl)-3-methyl-4-(3-nitrophenyl)-1H-pyrazolo[3,4-d]pyrimidine (3i) and 3j showed a significant gastrointestinal protection compared to the standard drug diclofenac sodium.

The aim of the present study was to develop and characterize coated chitosan-alginate beads containing cefaclor as a controlled release delivery system. Coated cefaclor beads were prepared by solvent evaporation techniques. Beads were found to be intact and spherical in shape. Their size range was 1.05 to 2.06. The loading efficiency showed maximum value when the concentration of cefaclor, chitosan and PEG 400 was 10 % (m/V), 0.5 % (m/V) and 2 % (V/V), respectively. Best retardation of cefaclor release from chitosan-alginate beads was achieved by coating with 15 % of shellac in formula F19. A significant antimicrobial activity (p < 0.05) against Staphylococcus aureus and Klebsiella pneumoniae was observed for formula F19 compared to the standard antibiotic disc. Furthermore, the simulated plasma profile showed the superiority of F19 in sustaining drug release for more than 12 h. Therefore, shellac coated chitosan-alginate beads could be considered a successful controlled release oral cefaclor dosage form.

The reaction of cyclopentanone with cyanoacetylhydrazine gave 2-cyano-2-cyclopentylideneacetohydrazide (1). Treatment of compound 1 with elemental sulphur in the presence of triethylamine afforded 2-amino-5,6-dihydro- -4H-cyclopenta[b]thiophene-3-carbohydrazide (2), which in-turn formed the corresponding intermediate diazonium salt. The latter was coupled with either ethyl cyanoacetate or ethyl acetoacetate to form 2-cyano-2-(3-(hydrazinecarbonyl)- 5,6-dihydro-4H-cyclopenta[b]thiophen-2-yl)hydrazono) acetate (3) and ethyl 2-(2-(3-(hydrazinecarbonyl)-5,6-dihydro- 4H-cyclopenta[b]thiophen-2-yl)hydrazono)-3-oxobutanoate (4), respectively. On the other hand, the reaction of compound 1 with either benzaldehyde or acetophenone afforded N’-benzylidene-2-cyano-2-cyclopentylideneacetohydrazide (7) and 2-cyano-2-(2-cyclopentylidene)phenylacetohydrazide (10), respectively. Moreover, compound 1 was used to synthesize 2-cyano-2-cyclopentylidene- N'-(arylthiazol-2(3H)-ylidene)acetohydrazides (6a,b), 2-(2-benzylidenecyclopentylidene)-2-cyanoacetohydrazide (8), 2-amino-N'-benzylidene-5,6-dihydro-4H- -cyclopenta[b]thiophene-3-carbohydrazide (9), 2-cyano- -2-(2-(2-phenylhydrazono)cyclopentylidene)acetohydrazide (11), N'-(1-chloropropan-2-ylidene)-2-cyano-2-cyclopentylideneacetohydrazide (12), and 2-cyclopentylidene-3- -(3,5-disubstituted-1H-pyrazol-1-yl)-3-oxopropanenitriles (13a,b) through its reaction with the respective reagents. Antitumor evaluation of the newly synthesized compounds against the three human tumor cells lines, namely, breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS cancer (SF-268) showed that some of the described compounds exhibited higher inhibitory effects towards the three tumor cell lines than the reference compound doxorubicin.

The aim of this study was to evaluate stability characteristics and kinetics behavior of abamectin (ABM) as a 1 % (m/V) topical veterinary solution. During the study, samples stressed at 55 and 70 °C were regularly analyzed for several parameters over 8 weeks on a chromatographic (HPLC) system, using a Prodigy C18, 250 x 4.6 mm, 5-μm, column eluting with 15 : 34 : 51 (V/V/V) water/methanol/ acetonitrile as mobile phase. The HPLC method was validated for precision, accuracy, linearity and specificity, and was found to be stability indicating. The results showed that degradation of ABM followed first-order kinetics and data on loss in kobs (s-1) and half life (t1/2, days) demonstrated ABM showing the maximum stability in glycerol formal. The degradation behavior of ABM varies from solvent to solvent. The effect of added alkali on pH change and loss of ABM was studied and found to be unique for all solvents and very distinct from typical hydrolysis degradation. The present study may serve as a platform to design and develop topical non-aqueous solutions of ABM for veterinary use given no such comprehensive efforts have been published to date on the stability profile of ABM in non-aqueous solvents.

Fenofibrate lipospheres were prepared by the melt dispersion technique. Critical parameters influencing particle size and entrapment efficiency were optimized by applying the L9 Taguchi experimental design. Entrapment efficiency of up to 87 % was obtained for the optimized formulation on increasing olive oil up to 30 % in the lipid carrier. Particle size analysis by microscopy and SEM revealed narrow particle size distribution and formation of discrete lipospheres of superior morphology. In vitro dissolution data best fitted the Higuchi model, indicating diffusion controlled release from porous lipid matrices. Prolonged release was obtained from stearic acid-olive oil lipospheres compared to cetyl alcohol-olive oil lipospheres due to the relatively hydrophobic matrix formed by stearic acid. Lipid lowering studies in Triton induced hyperlipidemia rat model demonstrated higher lipid lowering ability for fenofibrate lipospheres compared to the commercial product and plain drug.

The objective of the study was to prepare mefenamic acid (MA) sustained release matrix pellets and investigate the formulation parameters affecting pellet attributes and drug release in vitro. Amixer torque rheometer (MTR) was used to characterize the rheological properties of wet mass used in pellet formulation. Mefenamic acid pellets were prepared by extrusion/spheronization techniques using microcrystalline cellulose (MCC) in combination with lactose as pellet forming agents and water as the binding liquid. Also, the prepared pellets were characterized for their particle size and in vitro drug dissolution. The results revealed that the increase in lactose weight ratio to MCC resulted in a significant reduction of both maximum torque and binder ratios, while the addition of 2 % (m/m) polyvinyl pyrolidone (PVP) to MCC-lactose influenced only the mean torque rather than the wetting liquid (water). Particle size ranged from 945 to 1089 mm and had small span values (0.56-0.67). Furthermore, an inverse relation was observed between the rheological character of pellet wet masses (expressed by peak torque) and in vitro release rate. Increasing MAloading from 2.5 to 5 and 10 % was accompanied by a decrease in dissolution rates. In conclusion, properties of MA matrix pellets could be successfully monitored by controlling the wet mass characteristics by measuring torque.

Polysaccharide mucilage derived from the seeds of Plantago major L. (family Plantaginaceae) was investigated for use in matrix formulations containing propranolol hydrochloride. HPMC K4M and tragacanth were used as standards for comparison. The hardness, tensile strength, and friability of tablets increased as the concentration of mucilage increased, indicating good compactibility of mucilage powders. The rate of release of propranolol hydrochloride from P. major mucilage matrices was mainly controlled by the drug/mucilage ratio. Formulations containing P. major mucilage were found to exhibit a release rate comparable to HPMC containing matrices at a lower drug/polymer ratio (drug/HPMC 2:1). These results demonstrated that P. major mucilage is a better release retardant compared to tragacanth at an equivalent content. The results of kinetic analysis showed that in F3 (containing 1:2 drug/mucilage) the highest correlation coefficient was achieved with the zero order model. The swelling and erosion studies revealed that as the proportion of mucilage in tablets was increased, there was a corresponding increase in percent swelling and a decrease in percent erosion of tablets. The DSC and FT-IR studies showed that no formation of complex between the drug and mucilage or changes in crystallinity of the drug had occurred.

Percolation theory has been applied to study the drug release behaviour in multicomponent inert matrices containing ethylcellulose as a matrix forming polymer. Global influence of major formulation factors such as polymer viscosity, polymer particle size, drug and filler solubility and porosity of the tablets in drug release kinetics has been studied for the first time. Batches containing three viscosity grades of Ethocel™, microcrystalline cellulose (MCC) and lactose as fillers, a lubricant and flow aid mixture and three drugs with different solubility have been manufactured. For some batches, compression pressure was varied in order to obtain matrices with five levels of initial porosity. The behaviour of inert matrices was explained based on the percolation ranges of the main components of the formulation. The effect of the porosity percolation threshold was observed and the existence of a tricoherent drug-polymer-filler system is hypothesized.

In this study, an attempt was made to deliver pantoprazole in a sustained manner using delayed release tablets. The tablets were prepared by the wet granulation method using HPMC, cassava starch and polyvinyl pyrrolidine as polymers, Avicel PH 102 (MCC) as filler and potato starch as binder. The prepared tablets were evaluated for hardness, mass variation, friability and drug content uniformity, and the results were found to comply with official standards. The prepared tablets were coated using an enteric coating polymer such as cellulose acetate phthalate, Eudragit L100 and drug coat L100 by the dip coating method. The in vitro release was studied using pH 1.2 acidic buffer and pH 6.8 phosphate buffer and the study revealed that the prepared tablets were able to sustain drug release into the intestine. The anti-ulcer activity was evaluated by a water immersion stress induced ulcer model. The enteric coated pantoprazole tablets significantly reduced ulcer formation.