Source: Health Products Regulatory Authority (IE) Revision Year: 2021 Publisher: Bayer Limited, The Atrium, Blackthorn Road, Dublin 18
Pharmacotherapeutic group: Nervous system, other analgesics and antipyretics
ATC-Code: N02BA01
Acetylsalicylic acid belongs to the group of acidic nonsteroidal anti-inflammatory drugs with analgesic, antipyretic and anti-inflammatory properties. Its mechanism of action is based on irreversible inhibition of cyclo-oxygenase enzymes involved in prostaglandin synthesis.
Acetylsalicylic acid in oral doses of in general 0.3 to 1.0 g is used for the relief of pain and in minor febrile conditions, such as colds or influenza, for the reduction of temperature and relief of the joint and muscle pains.
It is also used in acute and chronic inflammatory disorders such as rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis.
Acetylsalicylic acid also inhibits platelet aggregation by blocking thromboxane A2 synthesis in platelets. Thus, it is used for various vascular indications at doses of in general 75 to 300 mg daily.
Experimental data suggest that ibuprofen may inhibit the effect of low dose aspirin on platelet aggregation when they are dosed concomitantly. In one study, when a single dose of ibuprofen 400mg was taken within 8h before or within 30 min after immediate release aspirin dosing (81mg), a decreased effect of ASA on the formation of thromboxane or platelet aggregation occurred. However, the limitations of these data and the uncertainties regarding extrapolation of ex vivo data to the clinical situation imply that no firm conclusions can be made from regular ibuprofen use, and no clinically relevant effect is considered to be likely for occasional ibuprofen use.
Following oral administration, acetylsalicylic acid is absorbed rapidly and completely from the gastro-intestinal tract. During and after absorption acetylsalicylic acid is converted into its main active metabolite, salicylic acid. Maximal plasma levels are reached after 10-20 minutes for acetylsalicylic acid and after 0.3-2 hours for salicylic acid, respectively.
Both acetylsalicylic acid and salicylic acid are extensively bound to plasma proteins and are rapidly distributed throughout the body. Salicylic acid passes into breast milk and crosses the placenta.
Salicylic acid is eliminated predominantly by hepatic metabolism. Its metabolites are salicyluric acid, salicylic phenolic glucuronide, salicylacyl glucuronide, gentisic acid, and gentisuric acid.
The elimination kinetics of salicylic acid is dose-dependent, as metabolism is limited by liver enzyme capacity. The elimination half-life therefore varies from 2 to 3 hours after low doses to up to about 15 hours at high doses. Salicylic acid and its metabolites are excreted mainly via the kidneys.
The preclinical safety profile of acetylsalicylic acid is well documented.
In animal studies, salicylates caused kidney damage at high dosages but no other organic lesions. Acetylsalicylic acid has been extensively studied in vitro and in vivo for mutagenicity; no relevant evidence of a mutagenic potential was found. The same applies to carcinogenicity studies.
Salicylates have exhibited teratogenic effects in animal studies and a number of different species. Implantation disorders, embryotoxic and fetotoxic effects and impairment of learning ability in the offspring after prenatal exposure have been described.
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