Rapid back flushed direct sample injection bio-analytical HPLC-UV method for therapeutic drug monitoring of terbinafine.

A rapid back flushed (BF) direct sample injection (DSI) high-performance liquid chromatography (HPLC) with UV detection (BF-DSI-HPLC-UV) has been developed to determine terbinafine (TERB) in human serum. For online solid phase extraction step, an isocratic mobile phase of phosphate buffer saline (pH 7.4) at 1 mL/min and a short protein-coated ODS column (PC-ODS-column) were used for the purification and enrichment of TERB. Two different chromatographic modes of PC-ODS-column were simultaneously operated. Macromolecular proteins were extracted by size-exclusion liquid chromatography, while TERB trapping and enrichment were achieved through reversed-phase liquid chromatography. The clear fraction containing TERB was transferred from the PC-ODS-column by BF mode onto the quantification step through a high pressure switching valve. An analytical mobile phase consisting of 80% methanol and 1% triethylamine in distilled deionized water (pH) 6 at 1 mL/min was used for the final separation on an ODS analytical column. TERB was quantified and detected by UV-detector at 224 nm. The proposed method showed high correlation coefficient (>0.999) over the concentrations range 4-1600 ng/mL with recoveries ranging from 98.48 to 93.86%. Measurement of TERB concentration in serum after administration of a single dose of 250 mg oral tablet was used to evaluate the applicability of the BF-DSI-HPLC-UV for pharmacokinetic study.

Bio-analytical liquid chromatographic-based method with a mixed mode online solid phase extraction for drug monitoring of fluconazole in human serum.

A simple, cost-effective and sensitive liquid chromatography-based bio-analytical method has been developed and validated for therapeutic drug monitoring of fluconazole (FLUC) in human serum. Integration of online mixed-mode solid-phase extraction (SPE) into the analytical system was the key for direct injection of untreated serum samples. A short protein-coated (PC) µBondapak CN silica column (PC-µB-CN-column) as a SPE tool and phosphate buffer saline (PBS) (pH 7.4) as an eluent were applied in the extraction step. PC-µB-CN-column operates in two different chromatographic modes. Using PBS, proteins were extracted from serum samples by size-exclusion liquid chromatography, while FLUC trapping was reversed-phase liquid chromatography dependent. FLUC was then eluted from the PC-µB-CN-column onto the quantification position using a mixture of acetonitrile-distilled deionized water (20:80, v/v) as an eluent and ODS analytical column. FLUC was separated at ambient temperature (22 ± 1 °C) and detected at 260 nm. The method was linear over the range of 200-10000 ng/mL. FLUC recovery in untreated serum samples ranged from 97.8 to 98.8% and showed good accuracy and precision. The reliability of the developed method was evaluated by studying the pharmacokinetic profile of FLUC in humans after an oral administration of a single 150 mg tablet.

Comparative pharmaceutical study on colon targeted micro-particles of celecoxib: in-vitro-in-vivo evaluation.

In order to target celecoxib which is a COX2 inhibitor, with potentials in the prevention and treatment of colitis and colon cancer, it was formulated as microparticles using the solvent/evaporation method and various pH-dependent Eudragit polymers. The in-vitro evaluation of the prepared microparticles showed spherical and smooth morphology. The encapsulation efficiency and yield were high, indicating that the method used is simple and efficient at this scale. The in-vitro release study showed no release in the acidic medium for 2 h followed by the release of the drug in pH 6.8 in case of Eudragit L100-55 and L100 and pH 7.4 in case of Eudragit S100. The pharmacokinetic parameters were calculated and method validation was performed to insure that it is suitable and reliable. Pharmacokinetic parameters were investigated by determining the Cmax, Tmax, AUC0-t, Kel, and t1/2 of the drug as a suspension and as microparticles. There was a significant difference (p < 0.05) in Tmax between the drug as a suspension and as microparticles. The effect of celecoxib on the degree of inflammation was examined on acetic acid induced colitis rat model and the drug was given as a suspension and as microparticles. The evaluation was done using macroscopical, microscopical and biochemical examination. There was a significant difference between the acetic acid control group and the treatment groups regarding all examination criteria in the order microparticles formulated using Eudragit S100 followed by Eudragit L100-55 while microparticles using Eudragit L100 and drug suspension showed almost the same results.