Arzneimittelforschung 2008; 58(8): 419-422
DOI: 10.1055/s-0031-1296530
Antibiotics · Antimycotics · Antiparasitics · Antiviral Drugs · Chemotherapeutics · Cytostatics
Editio Cantor Verlag Aulendorf (Germany)

Bioequivalence Study of Two Letrozole Tablet Formulations

Single dose, randomized, open-label, two-way crossover bioequivalence study of letrozole 2.5 mg tablets in healthy volunteers under fasting conditions
Augusto Filipe
1   Medical Department, Grupo Tecnimede, Prior Velho, Portugal
Susana Almeida
1   Medical Department, Grupo Tecnimede, Prior Velho, Portugal
2   Department of Pharmacology and Therapeutics, Universidad Autonoma de Barcelona
Ana Cristina Franco Spínola
1   Medical Department, Grupo Tecnimede, Prior Velho, Portugal
Fethi Trabelsi
3   Anapharm, Montreal, Canada
Jordi Ortuño
4   Anapharm Europe S.L., Barcelona, Spain
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15. Dezember 2011 (online)


The study was conducted in order to compare the bioavailability of two tablet formulations containing letrozole 2.5 mg (CAS 112809-51-5). Twenty healthy subjects were enrolled in a single-centre, bioequivalence, randomised, single-dose, open-label, two-way crossover study, performed under fasting conditions with a minimum washout period of 21 days. Plasma samples were collected up to 240 h post-dosing. Letrozole levels were determined by reverse liquid chromatography and detected by tandem mass spectrometry detection, LC/MS/MS method. Pharmacokinetic parameters used for bioequivalence assessment, area under the concentration-time curve from time zero to time of last non-zero concentration (AUC0–t) and from time zero to infinitive (AUC0–inf) and maximum observed concentration (Cmax), were determined from the letrozole concentration data using non-compartmental analysis.

The 90% confidence intervals obtained by analysis of variance were 90% geometric confidence intervals of the ratio (A/B) of least-squares means from the analysis of variance (ANOVA) of the In-transformed AUC0–t, and Cmax was within 80% to 125%. Bioequivalence between formulations was concluded both in terms of rate and extent of absorption.

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