Spectrophotometric methods for the determination of tamoxifen citrate.
Three simple and sensitive spectrophotometric methods for the determination of tamoxifen citrate have been developed. They are based on the formation of an ion-association complex between the drug and a dye, Erioglaucine A, which is extractable into chloroform and has an absorption maximum at 625 nm (method A), oxidation with excess potassium permanganate and the determination of unconsumed permanganate using Fast Green FCF (method B), or by the formation of a coloured cobalt thiocyante coordination complex which is extracted into benzene and measured at 635 nm (method C). Beer's law limits for methods A, B, and C are 0.5-3.0 mug ml(-1), 1.0-6.0 mug ml(-1) and 100-500 mug ml(-1), respectively. No interference was observed from tableting additives and the applicability of the methods was examined by analysing tablets containing tamoxifen. The quantities determined were 99.0-100.03% of the exptected values.
Single-Sweep Voltammetric Determination of Tamoxifen at Carbon Paste Electrode
Abstract A single-sweep voltammetric method was proposed for the determination of tamoxifen. The proposed method took advantage of both the accumulation of carbon paste electrode toward tamoxifen and the rapidity of single-sweep voltammetry. In HAc-NaAc (pH 4.1) buffer/methanol (85:15 v/v) mixed solution, an irreversible oxidation peak of tamoxifen was observed at 1.1 V (versus SCE). The second-order derivative peak current of tamoxifen and its concentration plots were rectilinear over the range of 7.0 × 10−10 ∼ 3.0 × 10−8 mol · l−1 with a detection limit of 1.0 × 10−10 mol · l−1 without any preconcentration. The proposed method was evaluated by analyzing tamoxifen citrate tablets, which was characterized by rapidity and higher sensitivity.
Studies on the metabolism and pharmacokinetics of tamoxifen in normal volunteers.
: The densitometric analytic procedure used for tamoxifen can also be used to quantify its desmethyl metabolite. In a study involving six healthy male volunteers, tamoxifen tablets were shown to be as bioavailable as a solution of tamoxifen citrate. After administration of a single dose of 20 mg, peak serum levels of tamoxifen were 42 ng/ml; those of the metabolite were 12 ng/ml. The half-lives of the drug and metabolite were approximately 4 and 9 days, respectively, after a single dose. After three widely separated single doses, a reversible increase in elimination half-life occurred.