Prostaglandins blood clotting time

Acetaminophen [a seat a MIN oh fen] and phenacetin [fe NASS e tin] act by inhibiting prostaglandin synthesis in the CNS. This explains their antipyretic and analgesic properties. They have less effect on cyclooxygenase in peripheral tissues, which accounts for their weak anti-inflammatory activity. Acetaminophen and phenacetin do not affect platelet function or increase blood clotting time, and they lack many of the side-effects of aspirin. [Note Phenacetin can no longer be prescribed in the United States because of its potential for renal toxicity. However, it is present in some proprietary preparations.]... 

Apart from the widespread use of aspirin to relieve pain, fever, and inflammation for the past loo years, more recently other beneficial effects have been found. It has been known for some time that aspirin will reduce the clotting of blood, as a result of its interference with the production of prostaglandins, which are involved with the clotting process (see box above p. 51). 

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