This study describes, for the first, the development and validation of a novel high-throughput micorwell spectrophotometric assay for determination of the quinolone antibiotic rosoxacin (ROS) in its bulk and capsules. The assay involved the reaction between ROS and sodium nitroprusside (SNP) forming a red-colored product exhibiting maximum absorption peak (λmax) at 455 nm. The reaction was carried out in 96-microwell plate and the absorbance of the colored-product was measured by microwell plate absorbance reader at 455 nm. The variables affecting the reaction were carefully investigated using the microwell format and the optimum conditions under were established. Under the optimized conditions, a linear relationship with good correlation coefficient (0.9992) was found between the absorbance of the ROS-SNP chromogen and ROS concentration in the range of 15-150 μg/mL. The limits of detection and quantification were 3.5 and 11.6 μg/mL, respectively. The assay showed high precision as the values of relative standard deviations (RSD) did not exceed 2%. The proposed assay was successfully applied to the determination of ROS in its capsules; the label claim percentages were 102.81±1.43%. The results were compared favorably with those of a reference pre-validated method. The proposed assay is practical and valuable in terms of its routine application in determination of ROS in its bulk and capsules in pharmaceutical quality control laboratories.

The kinetics and mechanism of hexacholroiridate(IV) oxidation of carboxymethyl cellulose (CMC) in aqueous solutions at a constant ionic strength of 0.1 mol dm−3 has been investigated spectrophotometrically. The experimental results showed first-order dependence in [IrCl6]2− and fractional first-order kinetics with respect to CMC concentration. An inversefractional first-order in [H+] was observed. A kinetic evidence for the formation of 1:1 intermediate complex was revealed. The reaction kinetics seems to be of considerable complexity where one chloride ion from hexacholoiridate(IV) oxidant may act as a bridging ligand between the oxidant and the substrate into the formed intermediate complex. The ionic strength was found to have a negligible influence on the reaction rates. The kinetic parameters have been evaluated, and a tentative reaction mechanism consistent with the kinetic results is discussed.

The kinetics of oxidation of tellurium(IV) by [IrCl6]2 in aqueous perchlorate solutions at a constant ionic strength of 0.1 mol dm3 have been investigated spectrophotometrically. The results showed a firstorder dependence in [IrCl6]2, fractional-first-order kinetics with respect to tellurium(IV) concentration and second-order overall kinetics. The increase in the [H+] was found to be accompanied by a decrease in the rate constants, i.e., the oxidation reaction was acid-inhibited. Kinetic evidence for the formation of a 1 : 1 intermediate binuclear complex between the two reactants has been obtained. The ionization constant of tellurium(IV) has been evaluated and found to be 1.69  103 dm3 mol1 at 25 1C. The kinetic parameters have been calculated and a tentative reaction mechanism consistent with the kinetic data is suggested.

tThe kinetics and mechanism of oxidation of alginate polysaccharide (Alg) by alkaline hexacyanoferrate(III)in basic solutions at a constant ionic strength of 1.0 mol dm−3have been investigated spectrophotomet-rically. The experimental results showed complex kinetics, where the reaction time curves of the pseudofirst-order plots were found to be of sigmoidal S-shape nature. The initial parts of the plots were relativelyfast, followed by slow-linear portions after short time periods. The oxidation rates were increased withincreasing the alkali concentration indicating that the oxidation is base-catalyzed. A kinetic evidence forformation of 1:1 intermediate complexes was revealed. The activation parameters have been evaluatedand a tentative reaction mechanism consistent with the kinetic results is suggested and discussed.

A simple and selective micellar electrokinetic chromatographic (MEKC) method has been developed for the analysis of five pharmaceutical binary mixtures containing three non-steroidal anti-inflammatory drugs (NSAIDs). The investigated mixtures were Ibuprofen (IP)–Paracetamol (PC), Ibuprofen (IP)–Chlorzoxazone (CZ), Ibuprofen (IP)–Methocarbamol (MC), Ketoprofen (KP)– Chlorzoxazone (CZ) and Diclofenac sodium (DS)–Lidocaine hydrochloride (LC). The separation was run for all mixtures using borate buffer (20 mM, pH 9) containing 15% (v/v) methanol and 100 mM sodium dodecyl sulphate (SDS) at 15 kV and the components were detected at 214 nm. Different factors affecting the electrophoretic mobility of the seven investigated drugs were studied and optimized. The method was validated according to international conference of harmonization (ICH) guidelines and United States pharmacopoeia (USP). The method was applied to the analysis of five pharmaceutical binary mixtures in their dosage forms. The results were compared with other reported high performance liquid chromatographic methods and no significant differences were observed.

The aim of the present study was to formulate lornoxicam into rectal suppositories as a new dosage form, to avoid its reported gastric irritation and to provide a rapid onset of action for children. Suppositories were prepared using fatty bases namely; witepsol H-15, suppocire AML, CM, witepsol E-75 and water soluble bases; mixtures of poly(ethylene glycol), PEGs, with different molecular weights. The prepared suppositories were investigated for their weight variation, drug content, melting point, fracture point, disintegration time and in-vitro release pattern. Moreover, aging study was performed both at room temperature and in refrigerator for 6 month. In-vivo study was also carried out in rabbits and the pharmacokinetic parameters were estimated. The prepared suppositories complied with the USP 34 pharmacopoeial requirements and PEGs-based suppositories released significantly higher amounts of lornoxicam compared with fatty bases (p0.05, ANOVA/Dunnett). Furthermore, lornixocam in selected formulations was found to be stable in both fatty and PEGs bases after the aging study. Formulation No. 5 showed a higher Cmax of 1.832±0.35 μg/ml, short tmax of 1 hr and absolute bioavailability of 80.1%. These findings suggest that lornoxicam was successfully formulated into rectal suppositories with a higher bioavailability.

The aim of this study was to develop liposomal-based (LBGF) and micro-emulsion-based (MBGF) gel formulations of croconazole to compare their topical delivery potential. Conventional gels were also prepared using various polymers such as sodium carboxymethyl cellulose (SCMC), Poloxamer 407, Carbopol 971P and chitosan. The in vitro release of croconazole from conventional gel formulations, LBGF and MBGF were carried out using cellophane membrane as permeation membrane. However, in vitro skin permeations studies of all formulations were carried out using rat skin. The results of the drug release/skin permeation studies indicated that the highest release was obtained from SCMC followed by chitosan, Poloxamer 407 and finally Carbopol 971P gel. Therefore, liposomes and micro-emulsions were loaded on Carbopol 971P gel. The drug release and skin permeation of croconazole from different LBGF and MBGF showed that MBGF had superior release/permeation than LBGF. MBGF having ethanol as co-surfactant showed higher release/permeation of drug than MBGF-containing propylene glycol. The analysis of data according to different kinetic models indicated that the release of drug from different LBGF and MBGF followed the Higuchi model. The antimicrobial activity of the different LBGF and MBGF of croconazole was carried out by measuring the inhibition zone (mm) and compared by the effect of miconazole cream as control. The different LBGF and MBGF showed an excellent activity against different species of fungi as compared with miconazole cream. Overall, these results indicated that developed LBGF and MBGF could have great potential for topical delivery of croconazole.

The aim of this study was to develop liposomal-based (LBGF) and micro-emulsion-based (MBGF) gel formulations of croconazole to compare their topical delivery potential. Conventional gels were also prepared using various polymers such as sodium carboxymethyl cellulose (SCMC), Poloxamer 407, Carbopol 971P and chitosan. The in vitro release of croconazole from conventional gel formulations, LBGF and MBGF were carried out using cellophane membrane as permeation membrane. However, in vitro skin permeations studies of all formulations were carried out using rat skin. The results of the drug release/skin permeation studies indicated that the highest release was obtained from SCMC followed by chitosan, Poloxamer 407 and finally Carbopol 971P gel. Therefore, liposomes and micro-emulsions were loaded on Carbopol 971P gel. The drug release and skin permeation of croconazole from different LBGF and MBGF showed that MBGF had superior release/permeation than LBGF. MBGF having ethanol as co-surfactant showed higher release/permeation of drug than MBGF-containing propylene glycol. The analysis of data according to different kinetic models indicated that the release of drug from different LBGF and MBGF followed the Higuchi model. The antimicrobial activity of the different LBGF and MBGF of croconazole was carried out by measuring the inhibition zone (mm) and compared by the effect of miconazole cream as control. The different LBGF and MBGF showed an excellent activity against different species of fungi as compared with miconazole cream. Overall, these results indicated that developed LBGF and MBGF could have great potential for topical delivery of croconazole.

The aim of this study was to measure and correlate the temperature dependent solubility data of tadalafil (TDL) in water, ethanol, propylene glycol (PG), polyethylene glycol-400 (PEG-400), and Transcutol from (298.15 to 333.15) K at atmospheric pressure using the shake flask method. The experimental solubilities were regressed by Apelblat equation with a relative deviation in the range of (1.20 to 5.74) % in all solvents investigated at (298.15 to 333.15) K. The root mean square deviation between experimental and calculated solubility was observed less than 1.10 in all solvents investigated. The correlation coefficients in water, ethanol, PG, PEG-400, and Transcutol were observed in the range of 0.997 to 0.999. The solubility of TDL was found to be increased with an increase in temperature in all solvents investigated. The mole fraction solubility of TDL was found to be higher in PEG-400 (1.86•10−2 at 298.15 K) and Transcutol (8.76•10−3 at 298.15 K) as compared to water (5.74•10−7 at 298.15 K), ethanol (1.77• 10−4 at 298.15 K) and PG (4.1•10−4 at 298.15 K).

The aim of this study was to measure and correlate the temperature dependent solubility data of tadalafil (TDL) in water, ethanol, propylene glycol (PG), polyethylene glycol-400 (PEG-400), and Transcutol from (298.15 to 333.15) K at atmospheric pressure using the shake flask method. The experimental solubilities were regressed by Apelblat equation with a relative deviation in the range of (1.20 to 5.74) % in all solvents investigated at (298.15 to 333.15) K. The root mean square deviation between experimental and calculated solubility was observed less than 1.10 in all solvents investigated. The correlation coefficients in water, ethanol, PG, PEG-400, and Transcutol were observed in the range of 0.997 to 0.999. The solubility of TDL was found to be increased with an increase in temperature in all solvents investigated. The mole fraction solubility of TDL was found to be higher in PEG-400 (1.86•10−2 at 298.15 K) and Transcutol (8.76•10−3 at 298.15 K) as compared to water (5.74•10−7 at 298.15 K), ethanol (1.77• 10−4 at 298.15 K) and PG (4.1•10−4 at 298.15 K).