Lysine acetylsalicylate

Aspirin (acetylsalicylic acid, Figure 7.9) is a derivative of salicyclic acid, which was first used in 1875 as an antipyretic and antirheumatic. The usual dose for mild pain is 300-600 mg orally. In the treatment of rheumatic diseases, larger doses, 5-8 g daily, are often required. Aspirin is rapidly hydrolysed in the plasma, liver and eiythrocytes to salicylate, which is responsible for some, but not all, of the analgesic activity. Both aspirin and salicylate are excreted in the urine. Excretion is facilitated by alkalinisation of the urine. Metabolism is normally very rapid, but the liver enzymes responsible for metabolism are easily saturated and after multiple doses the terminal half-life may increase from the normal 2-3 h to 10 h. A soluble salt, lysine acetylsalicylic acid, with similar pharmacological properties to aspirin, has been used by parenteral administration for postoperative pain. Aspirin in low doses (80-160 mg daily) is widely used in patients with cardiovascular disease to reduce the incidence of myocardial infarction and strokes. The prophylaxis against thromboembolic disease by low-dose aspirin is due to inhibition of COX-1-generated thromboxane A2 production. Because platelets do not form new enzymes, and COX-1 is irreversibly inhibited by aspirin, inhibition of platelet function lasts for the lifetime of a platelet (8-10 days). 

Lysine acetylsalicylate is a soluble form of salicylate developed for intravenous administration in acute pain. Its mode of action and scope of adverse effects are similar to those of aspirin (1), although it has a faster onset of action (2) and causes less gastrointestinal bleeding (3). 

Majluf-Cruz A, Chavez-Ochoa AR, Majluf-Cruz K, Coria-Ramirez E, Pineda Del AguUa I, Trevino-Perez S, Matias-Aguilar L, Lopez-Armenia JC, Corona de la Pena N. Effect of combined administration of clopidogrel and lysine acetylsalicylate versus clopidogrel and aspirin on platelet aggregation and activated GPIIb/IIIa expression in healthy volunteers. Platelets 2006 17(2) 105-7. 

A study in patients about to undergo surgery found that pretreatment with aspirin 1 g (given as intravenous lysine acetylsalicylate) one minute before induetion redueed the dosage of thiopental by 34%, from 5.3 to 3.5 mg/kg. Initially thiopental 2 mg/kg was given followed by increments of 25 mg until the eyelash reflex was abolished. The same study also found that oral probenecid 1 g given one hour before anaesthesia reduced the thiopental dosage by 23%, from 5.3 to 4.1 mg/kg. 

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