Acetaminophen is a?p-aminophenol?derivative with analgesic and antipyretic activities. Although the exact mechanism through which acetaminophen exert its effects has yet to be fully determined, acetaminophen may inhibit the?nitric oxide?(NO) pathway mediated by a variety of neurotransmitter receptors including?N-methyl-D-aspartate?(NMDA) and?substance P, resulting in elevation of the pain threshold. The antipyretic activity may result from inhibition of prostaglandin synthesis and release in the central nervous system (CNS) and prostaglandin-mediated effects on the heat-regulating center in the anterior hypothalamus.