Efficacy and Safety of Glucosamine Sulfate and Chondroitin Sulfate Combination in Treatment of Knee Osteoarthritis

Inclusion Criteria: * Male or female patient, older than 40 years of age, with knee osteoarthritis, based on clinical and radiological criteria (Kellgren-Lawrence grade 2 - 3), as specified: 1. Pain on movement of the affected knee for more than 15 days in the previous month with at least partial relief at rest; 2. Presence of osteophytes at least 1 mm in radiological imaging; * Knee osteoarthritis symptoms for at least six months prior to randomization. Exclusion Criteria: * Concomitant arthropathy that may confuse or interfere with assessing the efficacy or pain; * Patellar disease isolated, with primary symptoms of pain in the anterior knee, in the absence of radiological findings already described; * History of significant injury on collateral ligament, or anterior cruciate, or meniscus of the joint studied, with surgery, or immobilization for at least 3 weeks; * Arthroscopy of the affected knee in last 6 months; * Serum creatinine ≥ 1.8 mg/dL; * Diagnosis of diabetes mellitus; * Presence of any serious disease that could compromise the study, at the investigator discretion; * History of adverse event or allergy to acetaminophen, glucosamine sulfate or chondroitin sulfate; * Inability to understand and report the study questionnaire and the Visual Analogic Scale; * Inability to understand and consent to participate in this clinical study, expressed by signing the Informed Consent (IC); * Woman in pregnancy. * If female of childbearing potential, has a negative urine pregnancy test at Visit 0 and do not use, or do not agree to use, for the duration of the study, a medically acceptable form of contraception as determined by the investigator; * Alcohol intake ( \> 3 doses/day); * Oral or intramuscular corticosteroids four weeks prior to study entry; * Intra-articular injections with corticosteroids, into the studied knee, within the past three months; * Intra-articular injections in any other joint within the past four weeks; * NSAID users that don´t respect the washout period. Low-dose aspirin (325 mg or less, once daily) is allowed for cardio-protective benefit; * Intra-articular injections of hyaluronic acid within the past 12 months; * Use of topical analgesic in the joint studied or any other oral analgesic (with the exception of acetaminophen and other NSAID) two weeks prior to randomization; * Implementation of any other medical treatment for osteoarthritis one month prior to study entry; * Participation in last one year of clinical protocols, unless it can be direct benefit to patient; * Use of glucosamine and/or chondroitin sulfate three and six months prior the study entry, respectively; * Initiation of physical therapy two months prior to the study period; * Use of tetracycline and oral anticoagulants; * Use of vitamin D in doses in doses above the recommended; * Patients in alternative therapies; * Allergy to sulfonamides; * Presence of psychiatric disorders that could compromise the study.