Background: The use of stimulants such as bupropion, enzyme inhibitors such as anastrozole, androgens such as testosterone, antigonadotropins such as danazol, and diuretics such as chlorthalidone have been reported in urine drug testing programs for a wide variety of applications, including anti-doping tests in sport. These substances are subject to screening studies by the World Anti-Doping Agency (WADA). Anastrozole, chlorthalidone, testosterone and danazol are included on the WADA list of prohibited substances, while bupropion is included in the 2020 follow-up schedule of substances. This study aims to characterize the urinary excretion patterns of these substances following the administration of a single dose of each drug at a recommended therapeutic dose. Hypothesis: The administration of bupropion, anastrozole, testosterone, danazol or chlorthalidone in healthy subjects allows the generation of detectable concentrations of the drug in urine using the liquid chromatography technique coupled to mass spectrometry (LC-MS). Positive urine samples will enable to identify analytical strategies for doping control. Objectives: Primary objective: To measure the concentrations of various drugs (anastrozole, bupropion, chlorthalidone, danazol and testosterone) and their metabolites in urine for anti-doping control samples. The detection of new metabolites excreted in urine for longer periods of time than conventional metabolites will improve the ability to detect the abuse of anabolic steroids in sport. Secondary objective: To assess safety and tolerability of the drugs used. Methods: Phase I, unicentric, open, non-randomized, non-controlled clinical trial, with 5 parallel treatment conditions (anastrozole, bupropion, chlorthalidone, danazol and testosterone) administered in a single dose to male healthy volunteers (total n=11).