Reversed phase HPLC determination of tamoxifen in dog plasma and its pharmaco-kinetics after a single oral dose administration

Abstract

Recebido em 30/10/06; aceito em 25/5/07; publicado na web em 3/12/07The analytical method developed to evaluate tamoxifen in dog plasma samples was precise, accurate, robust and linear in the range of 5-200 ng/mL. The limits of detection and quantification were 0.981 ng/mL and 2.97 ng/mL, respectively. Besides, the intra-day precision and accuracy variations were 8.78 and 10.16%, respectively. Tamoxifen concentrations were analyzed by combined reversed phase liquid chromatography and UV detection (λ=280 nm). The study was conducted using an open randomized 2-period crossover balanced design with a 1-week washout period between the doses. This simple, rapid and selective method is suitable for pharmacokinetic, bioavailability and bioequivalence studies.

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“…Unchanged tamoxifen and N-desmethyl tamoxifen have been detected in urine in small amounts. In animals, Tamoxifen and/or its metabolites appear to undergo extensive enterohepatic circulation and are excreted in feces and urine as glucuronides, other conjugates, and unidentified polar metabolites [20].…”

Quantification of Tamoxifen in Pharmaceutical Formulations Using Micellar Liquid Chromatography

“…It is a white, odourless and fine crystalline powder, moderately soluble in water (0.5 mg/mL) and in acid (0.2 mg/mL). 12 Pharmaceutical producers have to check that the TAMO formulations contain the amount of active principle indicated in the label. Besides, TAMO therapy is long-term; therefore some patients are enticed to initially purchase a large amount of tablets and, improving the risk to take the last ones after the expiration date, and then containing a non-reliable amount of TAMO.…”

Application of Micellar Liquid Chromatography for The Determination of Antitumoral and Antiretroviral Drugs in Plasma

“…However, this method is easy to contaminate and quite expensive, so few laboratories can afford it. Other researchers suggest more accessible techniques, based on HPLC coupled with UV-visible spectroscopy absorbance diode array detector [18,19] and fluorescence detection [20]. The obtained results have been used for pharmacokinetics studies [16][17][18].…”

“…Other researchers suggest more accessible techniques, based on HPLC coupled with UV-visible spectroscopy absorbance diode array detector [18,19] and fluorescence detection [20]. The obtained results have been used for pharmacokinetics studies [16][17][18]. These methods usually require a strong purification of the sample in order to avoid the injection of harmful plasma compounds into the chromatographic system, involving tedious and time-consuming cleanup procedures, such as liquid/liquid [17,20] or solid/ liquid [18,19] extraction of the drug, and/or previous deproteinization [15,16].…”

“…The obtained results have been used for pharmacokinetics studies [16][17][18]. These methods usually require a strong purification of the sample in order to avoid the injection of harmful plasma compounds into the chromatographic system, involving tedious and time-consuming cleanup procedures, such as liquid/liquid [17,20] or solid/ liquid [18,19] extraction of the drug, and/or previous deproteinization [15,16]. Moreover, due to the different polarities of the drugs, mobile phases must be programmed as gradients, making the analysis of a large amount of samples a difficult task.…”