The purpose of this study is to determine whether 500 mg Glucosamine Sulfate / 400 mg Chondroitin Sulfate Capsules and 1500 mg Glucosamine Sulfate / 1200 mg Chondroitin Sulfate Sachet is effective and safe compared Cosamin DS ® Capsule in Treatment of Knee Osteoarthritis.

The Groups receive treatment for 16 weeks. The study is realized in 16 sites in Brazil.

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.