A reversed-phase high-performance liquid chromatographic method with electrochemical detection for the quantitative determination of diclofenac potassium in plasma was developed. Naproxen was used as the internal standard. The drug and internal standard were isolated from plasma by extraction with dichloromethane and 2 M hydrochloric acid. Chromatographic separation was performed on a C18 column with methanol-water (68:32, v/v) adjusted to pH 3.2 with phosphoric acid as mobile phase. The oxidation potential for detection was established by constructing a voltammogram for diclofenac. The quantification limit for diclofenac in plasma was 5 ng mL(-1). Linearity of the method was confirmed in the range 5-2000 ng mL(-1), correlation coefficient 0.9998. Within-day relative standard deviations (RSDs) ranged from 0.66 to 14.00% and between-day RSDs from 0.59 to 15.78%. The method was successfully applied for the determination of pharmacokinetic parameters after ingestion of a 50 mg dose of diclofenac. Studies were performed on 18 healthy volunteers of both sexes.

Depression is one of the most frequently occurring psychiatric conditions affecting the economic and social functioning of people all over the world. There are a few classes of drugs commonly used to treat patients with depression disorders. Therapeutic drug monitoring of antidepressants provides the possibility to reduce side effects and optimize the treatment of patients with depression. Hence, there is a need to develop reliable analytical methods for the determination of these agents in biological fluids. Moreover, an important part of understanding the mechanisms of action of these medicines is also associated with the recognition of the metabolites' function because of their potential influence on therapeutic benefits and/or adverse effects. Some of them possess the same primary activity as their parent compounds and may contribute to the therapeutic efficacy whereas the biochemical actions of other metabolites may be different from that of the parent drug. In this review, several validated high-performance liquid chromatographic, gas chromatographic and capillary electrophoretic methods for quantification of antidepressants and their metabolites in biofluids are compared. In addition, the review covers areas such as mechanism of actions, structure-activity relationships and metabolism of the cited antidepressants.

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A rapid and sensitive reversed-phase high performance liquid chromatographic method has been developed for the determination of metoclopramide in serum. The assay was performed after single extraction with ethyl ether using methyl parahydroxybenzoate as internal standard. Chromatographic separations were performed on C(18) stationary phase with a mobile phase composed of methanol-phosphate buffer pH 3 (30:70 v/v). Analytes were detected electrochemically. The quantification limit for metoclopramide in serum was 2 ng mL(-1). Linearity of the method was confirmed in the range of 5-120 ng mL(-1) (correlation coefficient 0.9998). Within-day relative standard deviations (RSDs) ranged from 0.3 to 5.5% and between-day RSDs from 0.8 to 6.0%. The analytical method was successfully applied for the determination of pharmacokinetic parameters after ingestion of 10 mg dose of metoclopramide. Studies were performed on 18 healthy volunteers of both sexes.