Flexaphen

this medicine is indicated for the relief of severe skeletal muscle spasm and pain associated with such medical and orthopaedic problems as: sprains and strains, myalgias, torticollis, tension headaches, traumatic muscle injuries, low back pain, fibrositis, cervical root and disc syndromes.

this medicine is contra-indicated in patients sensitive to either component.

Acetaminophen (Flexaphen) is metabolized (eliminated by conversion to other chemicals) by the liver. Therefore drugs that increase the action of liver enzymes that metabolize Acetaminophen (Flexaphen) [for example, carbamazepine (Tegretol), isoniazid (INH, Nydrazid, Laniazid), rifampin (Rifamate, Rifadin, Rimactane)] reduce the levels of Acetaminophen (Flexaphen) and may decrease the action of Acetaminophen (Flexaphen). Doses of Acetaminophen (Flexaphen) greater than the recommended doses are toxic to the liver and may result in severe liver damage. The potential for Acetaminophen (Flexaphen) to harm the liver is increased when it is combined with alcohol or drugs that also harm the liver.

Cholestyramine (Questran) reduces the effect of Acetaminophen (Flexaphen) by decreasing its absorption into the body from the intestine. Therefore, Acetaminophen (Flexaphen) should be administered 3 to 4 hours after cholestyramine or one hour before cholestyramine.

Acetaminophen (Flexaphen) doses greater than 2275 mg per day may increase the blood thinning effect of warfarin (Coumadin) by an unknown mechanism. Therefore, prolonged administration or large doses of Acetaminophen (Flexaphen) should be avoided during warfarin therapy

Occasional patients may develop gastrointestinal disturbances. It is possible, in rare instances, that Chlorzoxazone (Flexaphen) may have been associated withgastrointestinal bleeding. Dizziness, nausea, lightheadedness, malaise, or overstimulation may be noted by an occasional patient.

Drowsiness can occur with the use of this medicine and may be additive to drowsiness from the concomitant use of alcohol or other central nervous system depressants. Rarely, petechiae or ecchymoses may develop during treatment. Sensitivity reactions resulting in reversible skin rash or blood disorders may occur, but these are rare. Angioneurotic oedema and anaphylactic reactions are extremely rare. Rarely, a patient may note discolouration of the urine resulting from a phenolic metabolite of Chlorzoxazone (Flexaphen). This finding is of no known clinical significance. Infrequently, cases have been reported in which the administration of Chlorzoxazone (Flexaphen) or Chlorzoxazone (Flexaphen) containing products was suspected of causing liver damage. Several of these were subsequently determined to the due to underlying diseases rather than to Chlorzoxazone (Flexaphen) (i.e. carcinoma of the head of the pancreas, carcinoma with hepatic metastases, cholelithiasis). The remaining cases had a clinical picture consistent with viral hepatitis or a medicine induced hepatitis. In all of the latter cases the medicine was stopped and the patients recovered. It is not possible to state that the hepatitis in these patients was or was not medicine-induced.