THE NON-OPIOID ANALGESICS: DIFLUNISAL
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.
Diflunisal is the synthetic difluorophenyl derivative of salicylic acid. It is well absorbed after oral administration and causes less gastric irritation and bleeding than the equivalent dose of aspirin. It has a plasma half-life of 8 to 12 hours and can be given by twice daily administration. Excretion is reduced with renal impairment. Diflunisal is not converted to salicylic acid and its exact mechanism of action is unknown. Similar to aspirin it has been shown to inhibit prostaglandin production and platelet aggregation may be inhibited at higher therapeutic doses. It is effective in the treatment of pain from skeletal and soft tissue metastases in patients with cancer. It has little antipyretic activity.
The recommended dosage for diflunisal (Dolobid) is 500 mg twice a day on the first day, followed by 250-500 mg 12-hourly, the dose being adjusted according to response.
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