Comparative Bioavailability Study Between Etoricoxib and Tramadol, Administered Individually or in Combination

Inclusion Criteria: * The subjects must have been accepted by the COFEPRIS (Federal Commission for the Protection against Sanitary Risks) research subjects registration database. * Subjects without a subordinate relationship with the researchers. * Subjects who have given informed consent in writing. * Subjects of both genders, aged between 18 and 55 years, Mexicans. - -Subjects with no background of hypersensitivity or allergies to the drug under study or related drugs. * Body mass index between 18 and 27 kg/m2. * Healthy subjects, according to the results of the complete clinical history, electrocardiogram and the integration of the results of the clinical analyses, carried out in certified clinical laboratories, without alterations that require a medical intervention as a consequence. * Subjects with negative results for immunological tests (Anti-HIV, Anti-hepatitis B and C, VDRL). * Subjects with negative results in drug abuse screening tests: tetrahydrocannabinoids, cocaine and amphetamines. * Negative (qualitative) pregnancy test for women of childbearing potential without Bilateral tubal obstruction or hysterectomy. * In the case of women of childbearing age, they must have a birth control method, including barrier methods, non-hormonal intrauterine device, or bilateral tubal obstruction. Exclusion Criteria: * Subjects with recent history or physical examination evidence of gastrointestinal, renal, hepatic, endocrine, respiratory, cardiovascular, dermatological, or hematological disease that could affect the pharmacokinetic study of the product in research. * Subjects who have been exposed to drugs known as liver enzyme inducers or inhibitors or who have taken drugs potentially toxic within 30 days before the start of the study. * Subjects who have received any medication during the 7 days before the start of the study. * Subjects who have been hospitalized for any problem during the three months before the start of the study. * Subjects who have been rejected by the registry database of research subjects of COFEPRIS, for having participated in a clinical study within the three months prior to the start of the study. * Subjects who have received investigational drugs within the previous 60 days th the start of the study. * Subjects allergic to the study drug or related drugs. * Subjects who have ingested alcohol or drinks containing xanthines (coffee, tea, cocoa, chocolate, cola) or who have eaten charcoal-grilled food or grapefruit juice , at least 10 hours before the start of the study or who have smoked tobacco 24 hours before to the start of the internment period. * Subjects who have donated or lost 450 mL or more of blood within the previous 60 days of the beginning of the study. * Subjects with a history of drug and/or alcohol abuse according to the DSM-IV-TR (Diagnostic and Statistical Manual of Mental Disorders) Criteria. * Research subjects who presents alterations in the vital signs recorded during the selection.