Pharmacology: Pharmacodynamics: Paracetamol is an analgesic and antipyretic. The therapeutic effects of paracetamol are thought to be related to inhibition of prostaglandin synthesis, as a result of inhibition of cyclo-oxygenase. There is some evidence that it is a more effective inhibitor of central as opposed to peripheral cyclo-oxygenase. Paracetamol only has weak anti-inflammatory properties. This may be explained by the concept that inflammatory tissues have higher levels of cellular peroxides than other tissues and that cellular peroxides prevent inhibition of cyclo-oxygenase by paracetamol.
Pharmacokinetics: Paracetamol is rapidly and almost completely absorbed from the gastrointestinal tract. The concentration in plasma reaches a peak in 30 to 90 minutes and the plasma half-life is 1-4 hours after therapeutic doses. Paracetamol is relatively uniformly distributed throughout most body fluids. Binding of the drug to plasma proteins is variable; 20 to 30% may be bound at the concentrations encountered during acute intoxication. Following therapeutic doses 90-100% of the drug may be recovered in the urine within the first day. However, practically no paracetamol is excreted unchanged and the bulk is excreted after hepatic conjugation.
Pharmacokinetics in Renal Impairment: An increase in the interval between doses of paracetamol has been recommended for adults with chronic renal failure. Haemodiolysis may result in reduced plasma levels of paracetamol and therefore supplementary doses of paracetamol may be necessary in order to maintain therapeutic blood levels.
Pharmacokinetics in Hepatic Impairment: In mild liver disease, there is no evidence that paracetamol is harmful when taken at recommended doses. However, in severe liver disease, the plasma paracetamol half-life is significantly prolonged.
Promol is a mild analgesic and antipyretic, and is recommended for the treatment of most painful and febrile conditions, for example, headache including migraine and tension headaches, toothache, backache, rheumatic and muscle pains, dysmenorrhoea, sore throat, and for relieving the fever, aches and pains of colds and flu. Also recommended for the symptomatic relief of pain due to non-serious arthritis.
These doses should not be repeated more frequently than every four hours nor should more than four doses be given in any 24-hour period. For oral use only.
Adults: One to two tablets every 4 to 6 hours up to four times daily as required. Not more than 8 tablets per 24 hours.
Children: Children should not be given Promol for more than 3 days without consulting a doctor.
6-12 years: Half to one tablet three or four times daily as required.
Symptoms of paracetamol overdose 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, coma and death. Acute renal failure with acute tubular necrosis may develop even in the absence of severe liver damage. Cardiac arrhythmias and pancreatitis have been reported. Liver damage is possible in adults who have taken 10 g or more of paracetamol. It is considered that excess quantities of a toxic metabolite (usually adequately detoxified by glutathione when normal doses of paracetamol are ingested), become irreversibly bound to liver tissue. 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. Pallor, anorexia, nausea and vomiting are frequent early symptoms of paracetamol overdosoge. Hepatic necrosis is a dose related complication of paracetamol overdosage. Hepatic enzymes may become elevated and prothrombin time prolonged within 12 to 48 hours but clinical symptoms may not be apparent for 1 to 6 days after ingestion. Any patient who has ingested around 7.5 g or more of paracetamol in the preceding 4 hours should undergo gastric lavage. Administration of oral methionine or intravenous N-acetylcysteine which may have a beneficial effect up to at least 48 hours after the overdose, may be required. General supportive measures must be available. Paracetamol overdose may cause liver failure and so suspected overdose should always be investigated.
Promol is contraindicated in patients with a previous history of hypersensitivity to paracetamol.
Care is advised in the administration of paracetamol to patients with severe renal or severe hepatic impairment. The hazard of overdose is greater in those with non-cirrhotic alcoholic liver disease. Patients who are taking other potentially hepatotoxic drugs are at increased risk of paracetamol-induced hepatotoxicity. Do not exceed the stated dose. Patients should be advised not to take other paracetamol-containing products concurrently. If symptoms persist consult the doctor. If the patient has been diagnosed with liver or kidney impairment seek medical advice. Tablets contain methyl and propyl parabens.
Effects on Ability to Drive and Use Machines: No significant effect.
Human and animal studies have not identified any risk to pregnancy or embryofoetal development. Human studies have not identified any risk to lactation or the breast-fed offspring. Paracetamol crosses the placental barrier and is excreted in breast milk.
Paracetamol has been widely used and, when taken at the usual recommended dosage, side effects are mild and infrequent and reports of adverse reactions are rare. Skin rash and other allergic reactions occur rarely. Most reports of adverse reactions to paracetamol relate to overdosage with the drug. Isolated cases of thrombocytopenic purpura, haemolytic anaemia and agranulocytosis have been recorded. Chronic hepatic necrosis has been reported in a patient who took daily therapeutic doses of paracetamol for about a year and liver damage has been reported after daily ingestion of excessive amounts for shorter periods. A review of a group of patients with chronic active hepatitis failed to reveal differences in the abnormalities of liver function in those who were long-term users of paracetamol nor was the control of their disease improved after paracetamol withdrawal. Nephrotoxic effects following therapeutic doses of paracetamol are uncommon. Papillary necrosis has been reported after prolonged administration.
No significant interactions.
N02BE01 - paracetamol ; Belongs to the class of anilide preparations. Used to relieve pain and fever.
Tab 500 mg (white, plain, embossed with PARA 500 on one side and M+ on the other side) x 100 x 10's.