Bioavailability Study of Tramadol/APAP Tablets Under Fasting Conditions

Inclusion Criteria: * Healthy Males and females between 18 and 45 years of age inclusive * Informed of the nature of the study and given written informed consent. * Have a body weight within 15% of the appropriate range as defined in the 1983 Metropolitan Life Company tables and weighing at least 100lbs. Exclusion Criteria: * Hypersensitivity to Tramadol/ Acetaminophen, opioids such as morphine and codeine, or related compounds, or a history or seizures. * Any history of a clinical condition which might affect drug absorption, metabolism or excretion. * Recent history (within one year) of mental illness, drug illness, drug abuse or alcoholism. * Donation of greater than 500mL of blood in the past 4 weeks prior to study dosing or difficulty in donating blood. * Received an investigational drug within the 4 weeks prior to study dosing. * Currently taking any prescription medication, except oral contraceptives, within 7days prior to study dosing or over-the-counter medication within 3 days of the study dosing. * This prohibition does not include vitamins or herbal preparations taken as nutritional supplements for non-therapeutic indications as judged by the physician. * Tobacco use(\>5 cigarettes per day)in the 3 months prior to study dosing. * If female, the subject is lactating or has a positive pregnancy test at screening and prior to each of the two treatment periods. * Females of child bearing potential must use a medically acceptable method of contraception throughout the entire study period and for one week after the study is completed. * Medically acceptable methods of contraception that may be used by the subject and/or her partner are:oral contraceptive, progestin injection or implants, condom with spermicide, diaphragm with spermicide, IUD, vaginal spermicidal suppository, surgical sterilization of their partner(s) or abstinence. * females taking oral contraceptives must have taken them consistently for at least three months prior to receiving study medication.