Abstract
The analgesic activities of intracerebroventricular (icv) administrations of some analgesic drugs, morphine, indomethacin, diclofenac, aminopyrine and acetaminophen, were studied in comparison with those of systemic administrations in normal rats and adjuvant arthritic rats. A method forthe measurement of analgesic potency in normal rats and adjuvant arthritic rats were developed using the vocalization response as an indicator of pain resulting from electrical stimulation. The systemic and/or icv administered indomethacin and diclofenac produced much more potent analgesic action in adjuvant arthritic rats than in normal rats. Morphine, aminopyrine and acetaminophen given by the two routes showed roughly the same analgesic effect in both types of rats. Simultaneous systemic and icv administrations of indomethacin and/or diclofenac showed an additive effect in normal rats, but showed a synergistic effect rather than a simple additive effect in adjuvant arthritic rats. Those of morphine, aminopyrine and acetaminophen showed only additive effects in both types, except for that of aminopyrine in normal rats. Moreover, the brain and serum levels of non-metabolized indomethacin and aminopyrine were measured after the normal and adjuvant arthritic rats were systemically given these drugs. In adjuvant arthritic rats, the icv effective dose of indomethacin was the same as the brain level of non-metabolized indomethacin after the systemic administration. The effective dose of indomethacin administered icv in the normal rats was 17 times higher than the brain level of non-metabolized indomethacin administered systemically. The icv effective dose of aminopyrine was 4–4.5 times higher than the level of the brain concentration of non-metabolized drug in both types of rats. It was suggested that acidic nonsteroidal antiinflammatory drugs (NSAIDs) such as indomethacin and diclofenac specifically inhibit inflammatory pain, and the pain-relieving properties of acidic NSAIDs may be related to the central as well as the peripheral site of action.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
