A Study to Compare the Bioavailability of Two Tramadol Hydrochloride Tablet Products (50 mg and 200 mg, Respectively) at Steady-state Under Fasting Conditions

Inclusion Criteria: * Healthy, non-smoking, male and female subjects between the ages 18 to 55 years (inclusive). * Body mass within 10% of the ideal mass in relation to height and age, according to the BMI * Body mass not less than 70 kg. * Findings within the range of clinical acceptability in medical history and physical examination, and laboratory results with the "normal ranges" for the relevant laboratory tests (unless the clinical investigator considers the deviation to be irrelevant for the purpose of the study). * Normal ECG and vital signs, or abnormalities which the clinical investigator did not consider a disqualification for participation in the study * Willingness to undergo a pre-study physical examination and pre- and post-study laboratory investigations. * Ability to comprehend and willingness to sign both statements of Informed Consent (for screening and phase-related procedures) * Non-smokers or past smokers who stopped smoking at least three months before entering the study * For females, the following conditions had to be met: * had been postmenopausal for at least two years, or * had been surgically sterilized, or * was of childbearing potential, and all of the following conditions were met: * had a normal menstrual flow within one month before study entry, and * had negative urine pregnancy test at screening and on Day 1 of each study period. If the result of either test was positive, the subject would have been excluded from the study before receiving study medication. * had to agree to use an accepted method of contraception. The subject had to agree to continue with the same method throughout the study. Hormonal contraceptives were not allowed. Exclusion Criteria: * Evidence of psychiatric disorder, antagonistic personality, poor motivation, emotional or intellectual problems likely to limit the validity of consent to participate in the study or limit the ability to comply with protocol requirements. * History of, or current compulsive alcohol abuse (\> 10 drinks weekly), or regular exposure to other substances of abuse. * Use of any medication, prescribed or over-the-counter, within 2 weeks prior to the first administration of study medication except if this would not have affected the outcome of the study in the opinion of the clinical investigator. Use of hormonal contraceptives agents by females was not allowed. * Participation in another study with an experimental drug within 8 weeks before the first administration of study medication. * Treatment within the previous 3 months with any drug with a well-defined potential for adversely affecting a major organ or system with evidence to this effect. * Major illness during the 3 months before commencement of the screening period. * History of hypersensitivity to the study drug or any related drugs. * History of bronchial asthma. * History of epilepsy. * Relevant history or laboratory or clinical findings indicative of acute or chronic disease, likely to influence study outcome. * Donation or loss of blood equal to or exceeding 500 ml during the 8 weeks before the first administration of study medication. * Diagnosis of hypotension made during the screening period. * Diagnosis of hypertension made during the screening period or current diagnosis of hypertension. * Resting pulse of \> 100 beats per minutes or \< 45 beats per minutes during the screening period, either supine or standing. * Positive testing for hepatitis B antigen. * Significant liver disease, defined as active hepatitis or elevated liver enzymes (e.g., AST, ALT) \> 3 times the upper boundary of the normal range. * Positive urine screen for drugs of abuse. * Positive urine screen for tobacco use. * History of marijuana, barbiturates, amphetamine, or narcotic abuse within 12 months prior to study start. * Previous participation in a tramadol study. * pregnancy or lactation.