Phase III clinical trial, multicentre of superiority, randomized, double-blind, parallel groups, placebo-controlled and use of ibuprofen gel in the treatment of acute pain.

This study is designed for the relief of acute musculoskeletal pain, characterized by pain in muscles, ligaments, tendons, and nerves.

It is performed in participants of both sexes, over 18 years of age, who have pain of moderate intensity as a result of ankle sprains, upper limb contusions, thigh muscle strains, or torticollis.

The rationale for studying the topical use of ibuprofen is the possibility of an alternative treatment for musculoskeletal pain, avoiding systemic adverse events caused by oral administration.

Inclusion Criteria:

• Have signed the informed consent form;
• Participants of both genders aged ≥ 18 years;
• Present acute musculoskeletal pain as a result of: ankle sprains, upper limb contusions, thigh muscle sprains, or torticollis;
• Present pain of moderate intensity by VAS scale (3 ≤ VAS ≤ 7);
• Pain onset time is less than 36 hours;
• Present intact skin at the trauma site;
• Participants of both sexes with the potential to become pregnant must be truly abstinent or use a highly effective method of contraception throughout the period of 30 days before the administration of the drug until 30 days after the end of treatment;
• Agree to safety laboratory tests: pregnancy test, complete blood count, and biochemical profile;
• Be able to understand the nature and purpose of the trial, including the risks and adverse events.

Exclusion Criteria:

• Participants under the age of 18;
• Participants with musculoskeletal pain as a result of fractures or dislocations;
• Participants with mild pain (VAS < 3) at the time of selection;
• Participants with severe pain (VAS > 7) at the time of selection;
• Participants with pain onset time greater than 36 hours;
• Participants with a history of chronic pain and acute pain spikes;
• Participants with loss of skin integrity at the trauma site;
• Have a known hypersensitivity reaction to the trial medication or chemically related compounds;
• Have a prior history of the following comorbidities: asthma or other allergic conditions, uncontrolled heart failure, chronic kidney disease, chronic liver disease, active peptic ulcer disease, or gastrointestinal bleeding;
• Suspect for COVID-19 according to the criteria defined by the World Health Organization;
• Regular use of analgesics, non-steroidal analgesics or anticoagulants;
• Use of oral or topical corticoids in the injured area;
• Being on medications that have relevant interactions with the trial drugs, such as non-steroidal anti-inflammatory drugs (NSAIDs), warfarin, lithium, methotrexate, acetylsalicylic acid, corticosteroids, oral hypoglycemic agents, beta blockers, angiotensin-converting enzyme inhibitors, antihypertensive agents, and diuretics such as furosemide or thiazide;
• Have had oral or topical analgesic treatment, including use of non-steroidal analgesics, within 72 hours prior to the screening visit;
• Participants using traditional Chinese or Japanese therapy (acupuncture);
• Abusive use of alcoholic beverages;
• Women who are pregnant, breastfeeding, planning to become pregnant, or who test positive for pregnancy during the trial period;
• Have participated in a clinical trial within the last 12 months;
• Have any condition that would preclude participation in the trial in the physician's judgment.