Chlorzoxazone is a centrally acting skeletal muscle relaxant with sedative properties. It is claimed to inhibit muscle spasm by exerting an effect primarily at the level of the spinal cord and subcortical areas of the brain. Its effect beings within an hour of an oral dose and lasts for 3 to 4 hours.
Ketoprofen, a propionic acid deriative, is an NSAID.
Chlorzoxazone is readily absorbed from the gastrointestinal tract and metabolized in the liver. Chlorzoxazone is primarily excreted in the urine. Its half-life is 1.1 hours.
Ketoprofen is readily absorbed from the gastrointestinal tract; peak plasma concentrations occur about 0.5 to 2 hours after an oral dose. Ketoprofen is 99% bound to plasma proteins and substantial concentrations of drug are found in the synovial fluid. The elimination half-life in plasma is abot 1.5 to 4 hours. Ketoprofen is metabolised mainly by conjugation with glucuronic acid, and is excreted mainly in the urine.
Flexofan is also used in the treamtent of pain and mild inflammation in rheumatic disease and other musculoskeletal disorders, and after orthopaedic surgery and acute gout.
- Hypersensitivity to any of the components.
- Peptic ulceration
- Severe renal insufficiency
- The CNS effects of chlorzoxazone may be enhnaced by alcohol and other CNS depressants.
- Disulfiram reduced plasma clearance of chlorzoxazone.
- Ketoprofen is highly protein bound. In theory, interaction is possible following the concomitnat use of other protein-bound durgs, for example, anticoagulants, sulfonamides, and hydantoins.
- Methotrexate: The mode of action of NSAIDs in causing a hazardous interaction with methotrexate is uncertain, but may be via inhibition of the tubular secretion of the drug.
- Ketoprofen slighly inhibits the sodium diuresis inudced by furosemide.
- Ketoprofen may reduce the anithypertensive effect of beta-blockers.
- Lithium intoxication has been reported as a result of concurrent administration of ketoprofen.
- Probenecid increases the concentration of ketoprofen and of ketoprofen conjugates.
Photosensitivity reactions and cross-sensitivity to other drugs, notably bezafibrate, ciprofobate and fenofibrate.
The total dose should not exceed 6 capsules daily in divided doses.
- NSAIDs may cause an increased risk of serious cardiovascular thrombotic events, myocardial infarction (MI), and storke, which can be fatal. The risk may increase with duration of use. Patients with cardiovascular disease or risk factors for cardiovascular disease may be at a greater risk.
- NSAIDs are contraindicated for the treatment of preoperative pain in the setting of coronary arter bypass graft (CABG) surgery.
- NSAIDs cause an increased risk of serious gastrointestinal adverse events including bleeding, ulceration, and perforation of the stomach or intestine, which can be fatal.
- These events can occur any time during use and without warning symptoms.
- Elderly patients are at greater risk for serious gastrointestinal events.
Chlorzoxazone should not be given to patients with impaired liver function and should be discontinued if signs of liver toxicity appear. Patients should be advised to report to their doctor any signs or symptoms of possible liver toxicity such as fever, rash, juandice, dark urine, anorexia, nausea, vomiting, or right upper quadrant pain.
Chlorzoxazone may cause drowsiness; patients affected should not drive or operate heavy machinery.
The urine of patients taking chlorzoxazone may be coloured orange or reddish-purple by a phenolic metabolite.
Chlorzoxazone has been associated with acute attacks of porphyria and is considered usafe in porphyric patients.
Ketoprofen should be used with caution in patients with renal or hepatic impairment.