Each tablet contains:
- Active ingredients: Chlorzoxazone ----- 250 mg, Paracetamol ----- 450 mg.
- Inactive ingredients: Microcrystallin cellulose, Sod.starch glycolate, PEG 6000, Titanium dioxide, Purified talc, Magnesium stearate, PVP K 25.
Chlorzoxazone is centrally acting as skeletal muscle relaxant with sedative properties, it inhibits the muscle spasm by exerting an effect primarily at the level of the spinal cord and subcortical areas of brain. Paracetamol is a para-amino phenol derivative has analgesic and antipyretic effect.
Chlorzoxazone is reported to be completely absorbed after oral doses and peak plasma concentrations are achieved after1 to 2 hours, it is rapidly metabolized in the liver ,and excreted in the urine as the glucouronoid metabolite. The elimination half life of Chlorzoxazone is about 1 hour. Paracetamol is absorbed from GIT and reach peak plasma concentration after 10-60 minutes, paracetamol is distributed into most body tissues. it crosses the placenta and present in breast milk. Plasma- protein binding is negligible at usual therapeutic concentrations but increases with increasing concentrations. The elimination half-life of paracetamol about 1-3 hrs. It is metabolized in the liver and excreted in the urine as glucouronoid and sulfate conjugates.
Myoflex used for relief of the discomfort associated with acute painful musculoskeletal conditions: Torticollis –Muscle spasm –As adjunct to rest – As adjunct to physical therapy– Tension headache.
Dosage and Administration:-
1-2 tablets 3 times daily according to the severity of the case or as prescribed by the physician.
- Hypersensitivity to any component of the product.
- Patients with hepatic disorders.
- GIT disturbance, or rarely GIT bleeding.
- Drowsiness, dizziness, headache and overstimulation.
- Rarely allergic reactions (skin rashes, urticaria, pruritus and petechiae).
- Rarely patients may note urine discoloration resulting from phenolic metabolites of chlorzoxazone.
- Very rarely angioedema or anaphylactoid reactions.
- Haematologic reactions including thrombocytopenia, leucopenia, agranulocytosis.
- Some patients taking the product have developed jaundice, liver damage.
Early signs of paracetamol over dose: nausea, vomiting, sweating, abdominal pain, and liver damage occur at maximum72 – 96 hours after ingestion. Chlorzoxazone initially GIT disturbance such as nausea, diarrhea, together with drowsiness, dizziness, lightheadedness, loss of muscle tone , making voluntary movement and deep tendon reflex may be decreased or absent. blood pressure is lowered.
- Gastric lavage or induction of emesis.
- followed by administration of activated charcoal to reduce GIT absorption.
- taking acetylcystien or methionine as antidote for paracetamol.
- If respiration is depressed use oxygen supply.
- If hypotension occur use dextran, plasma concentrated albumin, or norepinephrin.
- Disulfiram: doubling the chlorzoxazone peak plasma concentrations and prolonged its elimination half life from 1 to 5 hours so should
adjust the recommended dose.
- Isoniazide: it inhibit the clearance of chlorzoxazone that resulting in increase the sedation, headache, nausea, so should adjust the recommended dose.
- Metoclopramide: increase the absorption of paracetamol.
- Cholestyramine: decrease the absorption of paracetamol.
- Also paracetamol affected by drugs as: Antibacterials (rifampicin), Anticoagulants (warfarin), Antivirals (zidovudine), Antiepileptics (phenytoin) Probenecid.
Pregnancy and Lactation:-
Category C. the safe use of chlorzoxazone has not been established, in pregnancy don t use without asking your doctor.
Precautions and Warning:-
Myoflex shouldn't be given to patients with impaired liver or kidney function, and should be stopped if signs of liver toxicity appears as (fever, Skin rash, jaundice, dark urine, nausea).
Package and Storage:-
- Carton box containing 1,2 or 10 strips each of 10 tablets + Pamphlet.
- Store below 25ºC away from light.
Instructions to Patients:-
- Keep the medicaments out of reach of children.
- Use under medical supervision.
Designed by Wattannia Co.