The non-opioid analgesics include salicylates, paracetamol and an expanding group of drugs known as the non-steroidal anti-inflammatory drugs (NSAIDs). The non-opioid analgesics all have a ceiling effect to their analgesic action and have many similarities with regard to mechanism of action, side effects and toxicity.
Aspirin-Aspirin or acetylsalicylic acid is the most frequently used salicylate. It is a semisynthetic derivative of the naturally occurring substance, salicylic acid.
Action-Aspirin inhibits the enzyme prostaglandin synthetase which is responsible for converting arachidonic acid produced by tissue inflammation into the various prostaglandins involved in the causation of pain.
Dose-The standard dose of aspirin is 600 mg each 4 hours; the dose should be adjusted according to effect and toxicity. Treatment for several days is required to achieve maximum response. Lower doses may not produce significant antiinflammatory effects. Increasing the dose above this level is unlikely to produce better analgesia and there is a much increased risk of toxicity.