Orally single dose administration of Tramadol 75 mg for ultra-rapid metabolizers and 100 mg for extensive and poor metabolizers will be administered with the objective to evaluate urine and blood concentrations in healthy volunteers.

Inclusion Criteria:

• Age ≥ 18 and ≤ 55 years.
• Weight ≥ 50 kg and ≤ 100 kg.
• Body mass index (BMI) ≥ 18 and ≤ 30.
• Negative serum pregnancy test (women only).
• Signed informed consent prior to any study-mandated procedure.

Exclusion Criteria:

• Smoker of more than 5 cigarettes per day in the last 3 months prior to participate in the study.
• History of psychiatric disorders, alcoholism or drug abuse.
• Positive urine pregnancy test.
• No highly effective anticonception measures during the trial.
• Breastfeeding.
• Positive blood or urine test for drugs of abuse or alcohol breath test prior to study drug administration.
• Any clinically relevant disease or condition (cardiovascular, renal, hepatic, endocrine, hematology, neurology o other acute or chronic diseases) that in the judgment of the investigator might interfere with the subject's ability to comply with study procedures or requirements and/or bias the interpretation of the study results and/or jeopardize the subject's safety.
• Major Surgery last 6 months.
• Ongoing gastrointestinal diseases or history of gastrointestinal surgery affecting absorption.
• Subjects with a clinically significant disease within one month prior to study drug administration.
• Any clinically relevant findings in physical examination, vital signs, 12-lead ECG and safety laboratory parameters.
• Positive hepatitis or HIV test.
• Known hypersensitivity to any drug or drug excipients.
• Use of drugs known to induce or inhibit hepatic drug metabolism within one month prior to study administration or during the study and use of citrus juice during the study.
• Any prescription or over-the-counter (OTC) product including herbal, homeopathic, vitamins, minerals and nutritional supplements within 2 weeks prior to study drug administration.
• Intake of more than 5 units per day of beverages containing xanthine (coffee, tea or cola drinks).
• Donation of blood or plasma within one month prior to study drug administration or transfusion of blood or plasma for medical/surgical reasons or intention to donate blood or plasma within one month after study drug administration.
• History of inadequate venous access and/or experience of difficulty donating blood.
• Not able/not willing to accept restrictions regarding diet, physical exercise, and consumption of alcohol and/or xanthine containing items when out of CRU.
• Subject included in a clinical study within 3 months prior to study drug administration.