CETACHLOR

Uncoated Tablet
Paracetamol 500 Mg IP
Chlorzoxazone 250 Mg USP

Therapeutic Indications:

• Paracetamol For the treatment of mild to moderate pain including headache, migraine, neuralgia, toothache, sore throat, period pains, aches and pains, symptomatic relief of rheumatic aches and pains and of influenza, feverishness and feverish colds.
• Chlorzoxazone For the relief of discomfort associated with acute painful musculoskeletal conditions. Moderate to Severe Muscle Spasm.

Posology and Method of Administration

Individual Dose
 

Paracetamol

Adults, The Elderly and Young Person’s 16 Years and over:2 tablets every 4 hours to a maximum of 8 tablets in 24 hours.
Children 6 – 9 Years: ½ tablet every 4 hours to a maximum of 4 doses in 24 hours.
Children 10 – 11 Years: 1 tablet every 4 hours to a maximum of 4 doses in 24 hours
Adolescents 12 – 15 Years: 1 to 1 ½ tablets every 4 hours to a maximum of 4 doses in 24 hours Do not give to children aged under 6 years of age.

Chlorzoxazone

Usual Adult Dosage One tablet three or four times daily. If adequate response is not obtained with this dose, it may be increased to (750 mg) three or four times daily. As improvement occurs dosage can usually be reduced.
Combination Dose The usual adult dosage is 1 tablets) 3-4 times or as directed by registered medical practitioner only. Because safety and effectiveness of in children have not been established, such use is not recommended

• Hypersensitivity to paracetamol, Chlorzoxazone or any of the constituents.
• CETACHLOR is contraindicated in patients with known intolerance to the drug.

• Paracetamol: Care is advised in the administration of paracetamol to patients with severe renal or severe hepatic impairment. The hazards of overdose are greater in those with non-cirrhotic alcoholic liver disease. Do not take more medicine than the label tells you to. If you do not get better, talk to your doctor.


• Chlorzoxazone: Serious (including fatal) hepatocellular toxicity has been reported rarely in patients receiving chlorzoxazone. The mechanism is unknown but appears to be idiosyncratic and unpredictable. Factors predisposing patients to this rare event are not known. Patients should be instructed to report early signs and/or symptoms of hepatotoxicity such as fever, rash, anorexia, nausea, vomiting, fatigue, right upper quadrant pain, dark urine, or jaundice. Chlorzoxazone should be discontinued immediately and a physician consulted if any of these signs or symptoms develop. Chlorzoxazone use should also be discontinued if a patient develops abnormal liver enzymes (e.g., AST, ALT, alkaline phosphatase and bilirubin.)

Interaction with Other Medicinal Products and Other Forms of Interaction:

• Cholestyramine: The speed of absorption of paracetamol is reduced by cholestyramine. Therefore, the cholestyramine should not be taken within one hour if maximal analgesia is required.


• Metoclopramide and Domperidone: The absorption of paracetamol is increased by metoclopramide and domperidone. However, concurrent use need not be avoided.


• Warfarin: The anticoagulant effect of warfarin and other coumarins may be enhanced by prolonged regular use of paracetamol with increased risk of bleeding; occasional doses have no significant effect.


• Chloramphenicol: Increased plasma concentration of chloramphenicol.

Fertility, Pregnancy and Lactation

• Paracetamol: A large amount of data on pregnant women indicate neither malformative, nor feto/neonatal toxicity. Epidemiological studies on neurodevelopment in children exposed to paracetamol in utero show inconclusive results. If clinically needed, paracetamol can be used during pregnancy however it should be used at the lowest effective dose for the shortest possible time and at the lowest possible frequency. Paracetamol is excreted in breast milk but not in a clinically significant amount. Available published data do not contraindicate breast feeding.


• Chlorzoxazone: The safe use of chlorzoxazone has not been established with respect to the possible adverse effects upon fetal development. Therefore, it should be used in women of childbearing potential only when, in the judgment of the physician, the potential benefits outweigh the possible risks.

Effects on Ability to Drive and Use Machines: None known.

Undesirable Effects

• Paracetamol: Adverse effects of paracetamol are rare. Very rare cases of serious skin reactions have been reported. There have been reports of blood dyscrasias including thrombocytopenia purpura, methaemoglobenaemia and agranulocytosis, but these were not necessarily causality related to paracetamol.
• Chlorzoxazone: It is possible in rare instances that chlorzoxazone may have been associated with gastrointestinal bleeding. Drowsiness, dizziness, lightheadedness, malaise, or over-stimulation may be noted by an occasional patient. Rarely, allergic type skin rashes, petechiae, or ecchymoses may develop during treatment. Angioneurotic edema or anaphylactic reactions are extremely rare. There is no evidence that the drug will cause renal damage. Rarely, a patient may note discoloration of the urine resulting from a phenolic metabolite of chlorzoxazone. This finding is of no known clinical significance.
• Overdose: Liver damage is possible in adults who have taken 10g or more of paracetamol. Ingestion of 5g or more of paracetamol may lead to liver damage if the patient has risk factors.
• Risk Factors: If the patient a) Is on long term treatment with carbamazepine, phenobarbitone, phenytoin, primidone, rifampicin, St John's Wort or other drugs that induce liver enzymes. Or b) Regularly consumes ethanol in excess of recommended amounts. Or c) Is likely to be glutathione deplete e.g. eating disorders, cystic fibrosis, HIV infection, starvation, cachexia.
• Symptoms: Symptoms of Paracetamol over Dosage in the First 24 Hours Are: Pallor, nausea, vomiting, anorexia and abdominal pain. Liver damage may become apparent 12 to 48 hours after ingestion. Abnormalities of glucose metabolism and metabolic acidosis may occur. In severe poisoning, hepatic failure may progress to encephalopathy, hemorrhage, hypoglycemia, cerebral edema, and death. Acute renal failure with acute tubular necrosis, strongly suggested by loin pain, hematuria and proteinuria, may develop even in the absence of severe liver damage. Cardiac arrhythmias and pancreatitis have been reported.
• Management: Immediate treatment is essential in the management of paracetamol overdose. Despite a lack of significant early symptoms, patients should be referred to hospital urgently for immediate medical attention. Symptoms may be limited to nausea or vomiting and may not reflect the severity of overdose or the risk of organ damage. Management should be in accordance with established treatment guidelines, see BNF overdose section.

  • Treatment with activated charcoal should be considered if the overdose has been taken within 1 hour. Plasma paracetamol concentration should be measured at 4 hours or later after ingestion (earlier concentrations are unreliable).

  • Treatment with N-acetyl cysteine may be used up to 24 hours after ingestion of paracetamol however, the maximum protective effect is obtained up to 8 hours post ingestion.

  • If required the patient should be given intravenous-N-acetyl cysteine, in line with the established dosage schedule. If vomiting is not a problem, oral methionine may be a suitable alternative for remote areas, outside hospital.

  • Management of patients who present with serious hepatic dysfunction beyond 24 hours from ingestion should be discussed with the NPIS or a liver unit.