Sodium Salicylate has analgesic, anti-inflammatory and antipyretic action. The types of pain amenable to relief by salicylates are those of low intensity, whether circumscribed or wide spread in origin; particularly amenable are headache, myalgia, arthralgia and other pains arising from integumental structures rather than from viscera. Salicylates alleviate pain by virtue of both a peripheral and a C.N.S. effect. Salicylates, by inhibiting the synthesis of prostaglandins that occur in inflamed tissues, prevent the sensitization of the pain receptors to mechanical stimulation or to chemicals, such as bradykinin, that appear to mediate pain response.
The antipyretic effect is usually rapid and effective in febrile patients. Regulation of body temperature requires a delicate balance between heat production and heat loss. The C.N.S., especially the hypothalamic nuclei, plays an indispensable role in regulating the peripheral mechanisms concerned with the production and loss of body heat. The hypothalamus regulates the set point at which body temperature is maintained. In fever, the balance between heat production and heat loss still persists except that the set point is at a higher level. The salicylates act to reset the "Thermostat" for normal temperature. Heat production is not inhibited, but heat dissipation is augmented by peripheral blood flow and sweating.