john@ur-tut.UUCP (John Gurian) (02/03/86)
> But, NO, Tylenol > has no effect in inhibiting Prostaglandin synthesis. > PG-E is only one of many endogenous pyrogens and does not directly cause > fever if injected into the hypothalamus but is neccessary for the development > of fever (put another way, it's necessary, but NOT sufficient). In fact, acetaminophen does inhibit cyclooxygenase, the enzyme involved in PG synthesis, but it does so only weakly at pharmacologic doses. PG-E will directly cause fever if injected into the cerebral ventricles of mammals. If injected peripherally in humans, no fever results, since it is metabolized in the lung too quickly. However, fever is a common side effect of methylated PG-E given women as an abortifacient; this is metabolized much more slowly. There is limited evidence that acetaminophen may inhibit cyclooxygenase in the CNS but not peripherally, which would explain the CNS effects of analgesia and antipyresia, with its lack of anti-inflammatory action peripherally. Still, this theory is far from proven or accepted. The genesis of fever is a complex & fascinating subject; an excellent review article may be found in the American Journal of Medicine, 72:799 1982, Dinarello & Wolff, "The Molecular Basis of Fever". -- -- John Gurian -- !rochester!tut!john