LOPRIN (Aspirin enteric coated)
Aspirin has analgesic, anti-inflammatory and anti-pyretic activity. It also has an antithrombotic action, mediated through inhibition of platelet activation, which has been shown to be useful in secondary prophylaxis following myocardial infarction and in patients with unstable angina or ischaemic stroke including cerebral transient attacks.
In the body it is rapidly converted to the salicylate form which has similar activity and works via the inhibition of the enzyme cyclo-oxygenase inhibiting prostaglandin synthesis. The enteric coat is intended to resist gastric fluid whilst allowing disintegration in the intestinal fluid. Owing to the delay that the coating imposes on the release of the active ingredient, enteric coated tablets are unstable for the short-term relief of pain.
Aspirin is rapidly absorbed after oral administration, with some hydrolysis to salicylate before absorption. Absorption is delayed by the presence of food and is impaired in patients suffering from migraine attacks. Absorption is more rapid in patients with achlorhydria and also following administration of polysorbates and antacids.
single and more multiple 100mg doses of enteric coated aspirin give systemic bioavailabilities of between 15% and 20% of that seen with immediate release aspirin preparations. Cmax of aspirin for several enteric-coated preparations has been shown to be approximately 100-200ng/ml with a half-life of approximately 1.7 hours. Plasma concentrations of salicylic acid increase disproportionately with dose-a 325mg dose having a half-life of 2-3 hours and higher doses showing lower plasma concentrations in the presence of an increased half-life due to a disproportionate increase in volume of distribution.
aspirin is found in the saliva, milk, plasma and synovial fluid at concentrations less than blood and crosses the placenta.
- Salicylate-extensive protein binding
- Aspirin-protein binding to a small extent
in the blood, rapid hydrolysis to salicylic acid; glucuronic acid/ glycine conjugation to form glucuronides and salicyluronic acid; oxidation of a small proportion.
Excreted in the urine mainly as salicyluronic acid. Salicylate is reabsorbed by renal tubules in acid urine, and alkaline diuresis will increase the rate of excretion; 85% of dose excreted as free salicylate.
For the secondary prevention of thrombotic cerebrovascular or cardiovascular disease and following by-pass surgery
Dosage and administration
- aspirin 75mg is for oral administration to adults only
- take the tablet with water, do not cut, chew or crush the tablet. Swallow whole
- the advice of a doctor should be sought before commencing therapy for the first time
- the usual dosage, for long term use, is 75mg-150mg once daily. In some circumstances a higher dose may be appropriate, especially in the short term and up to 300mg a day may be used on the advice of a doctor.
- hypersensitivity to aspirin or any other NSAIDs or any of the excipients
- active peptic ulceration or history of peptic ulceration
- haemophilia, other coagulopathies including hypoprothrombinaemia or concurrent anticoagulant therapy
- do not give to children aged under 16 years, unless specifically indicated (e.g for Kawasaki’s disease)
Special warning and precautions for use
Caution should be exercised in patients with allergic disease, impairment of hepatic or renal function (avoid if severe) and dehydration. Aspirin may also precipitate bronchospasm or induce attacks of asthma in susceptible subjects. The elderly may be more susceptible to the toxic effects of Salicylates. Continuous prolonged use of aspirin should be avoided in the elderly because of the risk of gastrointestinal bleeding.
Caution should be taken in patients with glucose-6-phosphate dehydrogenase deficiency as haemolytic anaemia may occur. Aspirin may interfere with insulin and glucagon in diabetes. Aspirin prolongs bleeding time, mainly by inhibiting platelet aggregation and therefore it should be discontinued several days before scheduled surgical procedures.
Haematological and haemorrhagic effects can occur, and may be severe. Patients should report any unusual bleeding symptoms to their physician. There is a possible association between aspirin and Reye’s syndrome when given to children. Reye’s syndrome is a very rare disease, which affects the brain and liver, and can be fatal. For this reason aspirin should not be given to children aged under 16 years unless specifically indicated (e.g. for Kawasaki’s disease).
Salicylates should not be used in patients with a history of coagulation abnormalities as they may also induce gastrointestinal haemorrhage, occasionally major. Aspirin should not be taken by patients with a stomach ulcer or a history of stomach ulcers.
Before commencing long term aspirin therapy for the management of cardiovascular or cerebrovascular disease patients should consult their doctor who can advise on the relative benefits versus the risk for the individual patient. Patient with hypertension should be carefully monitored.