Scientia Pharmaceutica

N. El-Enany ¹, F. Belal ¹, M. Rizk ¹

Affiliations
1 Department of Analytical Chemistry, Faculty of Pharmacy, University of Mansoura, 35516, Mansoura, EG

Abstract

A simple and sensitive kinetic spectrophotometric method was developed for the determination of isoxsuprine in pharmaceutical preparations. The method is based upon a kinetic investigation of the coupling reaction between isoxsuprine HCl and 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-CI) in borate buffer of pH 7.8 for a fixed time of 30 min. The absorbance of the yellow coloured product was measured at 395 nm. The absorbance-concentration plot was rectilinear over the range of 2-20 μg mL^-1 (r = 0.9994) with minimum detectability of 0.6 μg mL^-1 (1.75×10^-6M). The different experimental parameters affecting the development and stability of the colour were carefully studied and optimized. The determination of isoxsuprine by the fixed-concentration and rate-constant methods is also feasi

Keywords

Kinetic Determination, Isoxsuprine HCl, (NBD-CI), Pharmaceutical Preparations.

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F. Belal ¹, A. A. Al-Majed ¹, S. Julkhuf ¹

Affiliations
1 Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh-11451, SA

Abstract

The anodic behaviour of isradipine was studied using cyclic voltammetry (CV), direct current (DC_t) and differential-pulse (DPP) polarography. Isradipine exhibited well-defined anodic polarographic waves over the pH range of 4-8 in Britton-Robinson buffer (BRb). At pH 6, the analytical pH, the diffusion-current constant (Id) was 2.12 ± 0.42 (n = 4). The oxidation potential is -0.1 0 V vs. Ag/AgCI reference electrode with correlation coefficients of 0.9977 and 0.9948 in the DC_t and DPP modes, respectively. The current-concentration plots were rectilinear over the ranges 5-14 μg/ml and 2.4-12 μg/ml using the DC_t and DPP modes, respectively. The lower detection limit was 1.12 μg/ml (3.02 × 10^-6M) adopting the DPP mode. The proposed method was applied to commercial tablets and capsules, the % recoveries were 100.52 ± 1.267 and 99.4 ± 0.87 (n = 6) for the tablets and 101.3 ± 1.57 and 100.7 ± 2.10 (n = 6) for the capsules adopting both DC_t and DPP modes, respectively. The number of electrons involved in the electrode process was accomplished and a proposal of the electrode reaction was presented.

Keywords

Isradipine; Anodic Polarography; Dosage Forms.

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M Sultan ¹, H. Abdine ¹, N. Zoman ¹, F. Belal ¹

Affiliations
1 Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh-11451, SA

Abstract

A reversed-phase HPLC method with spectrophotometric detection was developed for the simultaneous determination of labetalol (LBT) and hydrochlorothiazide (HCD). The chromatographic separation was performed using a Microbondapak C₁₈ column (4.6 i.d. × 250 nm) and paracetamol as internal standard. A mobile phase consisting of 0.05 M phosphate buffer/acetonitrile of pH 4 (7:3) at a flow rate of 0.7 ml/min was used. The detection was affected spectrophotometrically at 302 nm. The working concentration range was 0.3-10 μg/ml with detection limits of 0.05 μg/ml for both drugs. The lower quantitation limit was 0.25 μg/ml in the two cases. The method was successfully applied to tablets, the % recoveries were 99.45±0.68 for LBT and 99.79±0.75 for HCD. The method was extended to the in-vitro determination in spiked human plasma. The % recoveries were 91.12±0.33 for LBT and 91.37±0.40 for HCD. The interday and intraday precision and accuracy were evaluated in plasma by calculating the % RSD (n=5) and the % error and were found to be in the ranges of 1.18-4.1% and 0.38-0.36% for both drugs, respectively.

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M. Rizk ¹, F. Belal ¹, F. Ibrahim ¹, S. Ahmed ¹, Z. A. Sheribah ¹

Affiliations
1 Department of Analytical Chemistry, Faculty of Pharmacy, University of Mansoura, Mansoura, 35516, EG

Abstract

A derivative UV-spectrophotometric method was developed for the analysis of two halogenated 8-hydroxyquinoline derivatives; iodochlorohyroxyquin (I) (Clioquinol) and di-iodohydroxyquin (II) (iodoquinol). The proposed method depends on the formation of Pd II-ligand complexes in methanol-acetonitrile mixture, which exhibits an UV-spectra with an appreciable value of ε. Zero order (⁰D), first order (¹D) and fourth order (⁴D) derivative measurements were applied for the quantitative analysis of the drugs. A linear correlation was established between absorbance and concentration for the ⁰D mode in the range 2-14 μg ml^-1 and 2-18 μg ml^-1 for (I) and (II) with average % recoveries of 99.83 ± 1.04 and 99.9 ± 10.64 respectively. Also a linear correlation was obtained between the trough of the peak and concentration for ¹D mode in the range of 0.16-0.8 μgml^-1 for both drugs with average % recoveries of 100.23 ± 1.04 and 100.18 ± 1.14 for (I) and (II) respectively. Besides, the ¹D mode was successfully applied for the analysis of binary mixture containing both (II) and metronidazole (III) in tablet formulations. The average % recoveries were 99.42 ± 0.358 and 98.81 ± 0.973 for (II) and (III) respectively. In the ⁴D mode, a linear correlation was attained between the amplitude of the peak and concentration in the range 0.1-0.8 μg ml^-1 for (I) and (II), with average % recoveries of 99.6 ± 0.84 and 100.06 ± 0.98. The limit of detection (LOD) was 2.1ng ml^-1 and 2.3ng ml^-1 for (I) and (II) respectively. The suggested method was successfully applied for accurate, sensitive and selective analysis of the studied drugs in bulk and single or combined dosage forms with average % recoveries of 99.74 ± 0.480-99.84 ± 0.515 and 99.44 ± 0.71-100.58 ± 1.06 for (¹D) and (⁴D) respectively. The results obtained were favorably compared to those given by a reference method.

Keywords

Derivative Spectrophotometry, Halogenated 8-hydroxyquinolines, Pd (II)-complexes, Clioquinol, Iodoquinol, Dosage Forms.

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M. Rizk ¹, F. Belal ¹, F. Ibrahim ¹, S. M. Ahmed ¹, N. M. El-Enany ¹

Affiliations
1 Department of Analytical, Chemistry, Faculty of Pharmacy, University of Mansoura, Mansoura, 35516, EG

Abstract

An accurate simple and selective kinetic procedure for the determination of certain 4-quinolones namely, norfloxacin (I), ofloxacin (II), enrofloxacin (III), fleroxacin (IV), ciprofloxacin (V) and pefloxacin (VI) is described. The procedure is based on reacting the studied compounds in acidic media (0.1 M HCL) with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in presence of cerium (IV) ammonium sulphate as an oxidant at room temperature for a fixed time of 20 min. For (I), (III), 12 min for (II) and 30 min for IV , V and VI, then the absorbance of the reaction product is measured at 630 nm. The concentration of the studied compounds is computed using the corresponding calibration curve equation for the fixed-time method. The absorbance-concentrations plot is rectilinear over the range 20-100 ug·ml^-1 for (I), 2-20 ug·ml^-1 for (II), 10-74 ug·ml^-1 for (III), 10-60 ug.ml^-1 for IV, 10-50 ug·ml^-1 for IV and 8-40 ug·ml^-1 for VI. The determination of the studied compounds by the fixed-concentration and rate constant methods is feasible with the calibration equation obtained, but the fixed-time method proved to be more applicable. The procedure was applied successfully to commercial tablets and ampoules and the results obtained were compared statistically with the reference methods.

Keywords

Kinetic Determination; 4-Quinolone Antibiotics; 3-Methyl-2-Benzothiazolinone Hydrazone HCL (MBTH); Ce. (IV); Pharmaceutical Analysis.

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