Coupling of Physical and Chromatographic Separation for Analyzing Cream Containing Miconazole, Mometasone Furoate and Gentamicin Sulphate.

High-performance liquid chromatographic method was developed, validated and applied for miconazole, mometasone and gentamicin in Momenta® cream. Physical separation was applied using two extraction procedures due to different solubility of the three components. First, a methanolic extract of the cream contained miconazole and mometasone was chromatographed on ODS-3 Inertsil C18 column (150 × 4.6, 5 µm) using acetonitrile: water (80:20, v/v) as a mobile phase, flow rate 1.5 mL·min-1, scanned at 230 nm, showing tR 2.817 and 6.808 min for mometasone and miconazole, respectively. Second, an aqueous extract of the cream containing gentamicin was derivatized with o-phthalaldehyde in order to enhance the gentamicin UV detection and subjected to ion pairing chromatography on Inertsil ODS-3 C18 column (150 × 4.6, 5 µm), using methanol: 0.025 M heptane sulphonic acid: glacial acetic acid (75:20:5, by volume) as a mobile phase, flow rate 0.8 mL·min-1, scanned at 330 nm where the three active gentamicin isomers were separated at tR 11.7, 15.6 and 18.3 min. Suitability of this method for quantitative estimation of the drugs was proved by validation according to ICH guidelines. The method was selective, precise and accurate so could be used for analysis of cream formulation in QC labs.

Monitoring of Clotrimazole Degradation Pathway in Presence of its Co-formulated Drug.

Two stability-indicating chromatographic methods for the determination of clotrimazole and its two acid induced degradation products, with dexamethasone acetate without prior separation. First method depends on RP-HPLC utilizing ODS-3 Inertsil C18 column. Mobile phase consists of acetonitrile:phosphate buffer (pH 6.0) in ratio (65:35, v/v) with flow rate 1.5 mL/min and UV-detection at 220 nm. Linearity range 1.0-75.0 µg/mL for clotrimazole and 2.0-75.0 µg/mL for dexamethasone with mean percentage recovery of 99.49 ± 1.10 for CLT and 99.60 ± 1.06 for DA. Second method depends on HP-TLC. Developing system is composed of chloroform:ethyl acetate in the ratio of (5:3.5, v/v), scanned at 220 nm. Linearity range 1.0-12.0 µg/band for clotrimazole and 1.0-20.0 µg/band for dexamethasone with mean R% of 99.33 ± 0.76 for clotrimazole and 99.77 ± 0.99 for dexamethasone. Conditions and parameters affecting the separation of the cited components without interference of the degradation products are tested and optimized. Suitability of the methods for quantization of the drugs concentrations is proven by validation as instructed from the ICH. Validation results and statistical treatment of the data demonstrate reliability of these methods. Kinetics of acid degradation process of clotrimazole are investigated by the proposed HPLC method and the order rate constant, half life and shelf life are computed.