Stability indicating RP-HPLC method for simultaneous determination of gatifloxacin and dexamethasone in binary combination

Abstract In this study, conditions were optimized for development of a simple RP-HPLC method for simultaneous analysis of gatifloxacin and dexamethasone in different matrices like pharmaceuticals, human serum and urine. Good separation of gatifloxacin and dexamethasone from the induced degradation products was accomplished using C8 as stationary phase; 0.02 M phosphate buffer (pH 3.0) and methanol (42:58 v/v) as mobile phase. The concentration was measured with DAD at 270 nm. Linearity was observed in the range of 0.000040-0.000280 mol/L for gatifloxacin (r2≥0.999) and 0.000013-0.000091 mol/L for dexamethasone (r2≥0.999). Both the analyte peaks were completely separated from the peaks of induced degradation products as indicated by the peak purity index (≥0.9999 for both analytes). The optimized method is recommended to be used for concurrent analysis of gatifloxacin and dexamethasone in different matrices.

Simultaneous RP-HPLC determination of sparfloxacin and dexamethasone in pharmaceutical formulations

The present study describes the development and subsequent validation of simple and accurate stability indicating RP-HPLC method for the determination of sparfloxacin and dexamethasone in pharmaceutical formulations in the presence of their stress-induced degradation products. Both the drugs and their stress-induced degradation products were separated within 10 minutes using C8 column and mixture of methanol and 0.02 M phosphate buffer pH 3.0 (60:40 v/v, respectively) as mobile phase at 270 nm using diode array detector. Regression analysis showed linearity in the range of 15-105 µg/mL for sparfloxacin and 5-35 µg/mL for dexamethasone. All the analytes were adequately resolved with acceptable tailing. Peak purity of the two drugs was also greater than 0.9999, showing no co-elution peaks. The developed method was applied for simultaneous determination of sparfloxacin and dexamethasone in pharmaceutical formulations for stability studies.

O presente estudo descreve o desenvolvimento e a subsequente validação de indicador de estabilidade simples e acurada por RP-HPLC para a determinação de esparfloxacino e dexametasona em formulações farmacêuticas na presença de produtos de degradação induzidos por estresse. Tanto os fármacos quanto os produtos de degradação induzidos pelo estresse foram separados em 10 minutos, utilizando coluna C8 e mistura de methanol e tampão fosfato 0,02 M, pH 3,0 (60:40 v/v, respectivamente) como fase móvel e detector de arranjo de diodo a 270 nm, A análise de regressão mostrou linearidade na faixa de 15-105 µg/mL para esparfloxacino e 5-35 µg/mL para a dexametsona. Todos os analitos foram resolvidos adequadamente com tailing aceitável. O pico de pureza dos dois foi maior que 0.9999, não mostrando picos de co-eluição. O método desenvolvido foi aplicado para a determinação simultânea de esparfloxacino e dexametasona em formulações farmacêuticas e para estudos de estabilidade.

Stability indicating HPLC method for the simultaneous determination of moxifloxacin and prednisolone in pharmaceutical formulations.

BACKGROUND: A simple, specific, and fast stability indicating reverse phase liquid chromatographic method was established for instantaneous determination of moxifloxacin and prednisolone in bulk drugs and pharmaceutical formulations. RESULTS: Optimum chromatographic separations among the moxifloxacin, prednisolone and stress-induced degradation products were achieved within 10 minutes by use of BDS Hypersil C8 column (250 X 4.6 mm, 5 µm) as stationary phase with mobile phase consisted of a mixture of phosphate buffer (18 mM) containing 0.1% (v/v) triethylamine, at pH 2.8 (adjusted with dilute phosphoric acid) and methanol (38:62 v/v) at a flow rate of 1.5 mL min-1. Detection was performed at 254 nm using diode array detector. The method was validated in accordance with ICH guidelines. Response was a linear function of concentrations over the range of 20-80 µg mL-1 for moxifloxacin (r2 ≥ 0.998) and 40-160 µg mL-1 for prednisolone (r2 ≥ 0.998). The method was resulted in good separation of both the analytes and degradation products with acceptable tailing and resolution. The peak purity index for both the analytes after all types of stress conditions was ≥ 0.9999 indicated a complete separation of both the analyte peaks from degradation products. The method can therefore, be regarded as stabilityindicating. CONCLUSIONS: The developed method can be applied successfully for simultaneous determination of moxifloxacin and prednisolone in pharmaceutical formulations and their stability studies.

2,5-Dichloro-N-(4-meth-oxy-phen-yl)benzensulfonamide.

In the title compound, C(13)H(11)Cl(2)NO(3)S, the dihedral angle between the benzene rings is 74.37 (3)°. In the crystal, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into chains along the b axis.

L-Ascorbate, a strong inducer of L-dopa (3,4-dihydroxy-L-phenylalanine) production from pre-grown mycelia of Aspergillus oryzae NRRL-1560.

The inductive effect of L-ascorbate on the microbiological production of L-dopa (3,4-dihydroxy-L-phenylalanine) from Aspergillus oryzae NRRL-1560 was investigated. All biochemical reactions were performed aerobically using mould mycelia as a source of enzyme tyrosinase and acetate buffer (pH 3.0) as an extractant. L-Tyrosine as a substrate was added at a level of 2.5 mg/ml. Maximal L-dopa production (1.876 mg/ml) was achieved when L-ascorbate (5.0 mg/ml) was added 6 min after the initiation of the biochemical reaction at 50 degrees C, consuming 2.144 mg/ml L-tyrosine. The performance of fuzzy-logic control of the reaction was found to be highly promising for improvement of the substrate conversion rate (~80%). After optimizing the reaction conditions, particularly the addition of L-ascorbate, an increase in L-dopa yield of 22.96% was achieved compared with the control (without ascorbate addition) when the process variables, namely buffer pH, L-tyrosine concentration and reaction temperature, were further identified using a two-factorial Plackett-Burman design.

N-(4-Hydroxy-phen-yl)benzene-sulfon-amide.

The title compound, C(12)H(11)NO(3)S, synthesized by the reaction of benzene sulfonyl chloride with para-amino-phenol, is of inter-est as a precursor to biologically active sulfur-containing heterocyclic compounds. The structure is stabilized by N-H⋯O and O-H⋯O hydrogen bonds.

Hexaaqua-chromium(III) pyridine-2,4,6-tricarboxyl-ate dihydrate.

The chromium(III) atom in the title salt, [Cr(H(2)O)(6)](C(8)H(2)NO(6))·2H(2)O, has an octa-hedral coordination geometry. In the crystal, the cation, anion and uncoordinated water mol-ecules, both of which are disordered over two positions in a 1:1 ratio, are linked by O-H⋯O hydrogen bonds.

N-(4-Meth-oxy-phen-yl)-4-methyl-benzene-sulfonamide.

In the title compound, C(14)H(15)NO(3)S, the dihedral angle between the aromatic rings is 59.39 (14)° and the C-S-N-C torsion angle is -71.4 (2)°. In the crystal, a supra-molecular chain running along the b axis with a C(4) graph set is formed via N-H⋯O hydrogen bonds.

2,4,6-Trimethyl-pyridinium nitrate.

In the title compound, C(8)H(12)N(+)·NO(3) (-), the cation lies on a mirror plane and the N and one C atom lie on a twofold axis. In the crystal, the anions and cations are linked by N-H⋯O inter-actions along the b axis and a short N-O⋯π contact [3.2899 (5) Å] also occurs.

2-(4-Methyl-benzene-sulfonamido)-2-phenyl-acetic acid.

In the title compound, C(15)H(15)NO(4)S, the dihedral angle between the phenyl and benzene rings is 46.0 (3)° and a weak intra-molecular N-H⋯O inter-action is present. The crystal structure is stabilized by inter-molecular O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds.

7-Benzene-sulfonamido-3-ethenyl-8-oxo-5-thia-1-aza-bicyclo-[4.2.0]oct-2-ene-2-carboxylic acid methanol solvate.

In the title compound, C(15)H(14)N(2)O(5)S(2)·CH(4)O, the six-membered ring fused to the ß-lactam unit adopts a twisted conformation. In the crystal structure, the component mol-ecules are linked into a three-dimensional framework through inter-molecular N-H⋯S, N-H⋯O and O-H⋯O hydrogen bonds and C-H⋯O contacts.