New approach for simultaneous analysis of commonly used antigout drugs by HPLC/UV method; Application in pharmaceutical and biological analysis

Therapeutic drug monitoring of six contraindicated/co-administered drugs by simple and green RP-HPLC-PDA; application to spiked human plasma

Therapeutic drug monitoring is an important clinical testing of the drugs to monitor their concentrations in plasma in order to guarantee their optimal impact, and to avoid any side effects resulting from drug-drug interactions. A green reversed-phase high-performance liquid chromatographic method using a photodiode array detector (RP-HPLC-PDA) was developed for the simultaneous determination of three carbapenem antibiotics (Imipenem, ertapenem, and meropenem) with the co-formulated drug (cilastatin) and contraindicated drugs (probenecid and warfarin) in spiked human plasma. The separation was achieved at 25 °C using a gradient elution of a mixture of mobile phase A: methanol and mobile phase B: phosphate buffer (pH 3.0). The photodiode array detector was adjusted at 220 nm. Bioanalytical method validation was carried out as per the FDA guidelines, and the method showed good linearity ranges for the six drugs that included their Cmax levels along with low limits of quantification. Based on the results, the method was found to be accurate and precise; with high % recovery and good % RSD, respectively. The method was successfully applied to spiked human plasma, signifying a good potential to be implemented in future TDM studies of these drugs when co-administered together.

A stable and highly luminescent 3D Eu(III)-organic framework for the detection of colchicine in aqueous environment

The metal-organic framework materials have an important application as sensors. In this work, a microporous three-dimensional (3D) Eu(III)-organic framework (Eu-MOF), [Eu₂(3,5-bct)(phen)₂(ox)₂(H₂O)]·H₂O, was constructed from 3,5-bis(3'-carboxyphenyl)-1,2,4-triazole (3,5-H₂bct), oxalate (ox) and 1,10-phenanthroline (phen) as a luminescent sensor. The free volume was found to be 15.7% per unit volume ignoring the free water molecules. The Eu-MOF showed bright red light due to the emission at 622 nm (⁵D₀ → ⁷F₂ transition) of the Eu(III) with high quantum yield (QY, 52.51%). The Eu-MOF exerted high luminescence stability in common organic solvents as well as aqueous solutions within a wide pH range from 4 to 11. Based on the luminescent Eu-MOF, the sensing behavior for colchicine in the aqueous environment was studied. Highly selective and sensitive detection (LOD = 2.43 × 10^-5 mol L^-1) of colchicine was observed by the Eu-MOF even in the presence of potential interfering components. The sensing mechanism for colchicine was investigated by experimental and theoretical results. It is worth noting that a film (Film@Eu-MOF) prepared by loading Eu-MOF showed intense characteristic red light emission under UV light. The luminescence color changed immediately from red to colorless when the Film@Eu-MOF came in contact with colchicine. Highly sensitive and rapid detection of colchicine in wastewater was achieved using this Film@Eu-MOF, which could be identified by the naked eye. The experimental results suggest that the synthesized Eu-MOF has potential application as a luminescent sensing material for pollutants in the environmental system.

Stability-Indicating Chromatographic Methods for the Simultaneous Determination of Probenecid and Colchicine in Their Combined Tablet

Two stability-indicating chromatographic methods have been established and validated for concurrent determination of probenecid (PRO), colchicine (COL) along with the degradation product of colchicine (COL deg). PRO and COL were exposed to a stress stability study, which includes acidic, alkaline, oxidative, photolytic and thermal degradations. Chromatographic methods included the use of thin layer chromatography (TLC-densitometry) and high performance liquid chromatography (HPLC). In the first method, separation was achieved by using aluminum TLC plates that were precoated with silica gel G.F254 as the stationary phase and ethyl acetate-methanol-33%ammonia (8:1:1, by volume) as a mobile phase. The obtained chromatograms were scanned at 254 nm. The second method was based on HPLC using a RP- C18 column with isocratic elution. Good separation was obtained through a mobile phase comprised of phosphate buffer pH 5-acetonitrile (70:30, v/v) at a flow rate of 1.0 mL min-1 and ultraviolet detection at 254 nm. Different parameters affecting efficiency of the two methods were studied accurately for optimum separation of the three cited components. The suggested methods were validated according to the International Conference on Harmonization (ICH) guidelines and were applied for bulk powder and commercial tablets.