title: Interaction between inhibitors of inducible nitric oxide synthase and cyclooxygenase in Brewer's yeast induced pyrexia in mice: an isobolographic study.
abstract: We studied the interaction of S-methylisothiourea (a selective inducible nitric oxide synthase inhibitor) with rofecoxib (selective cyclooxygenase-2 inhibitor) and mefenamic acid (non-selective cyclooxygenase inhibitor) in Brewer's yeast-induced pyrexia in mice by isobolographic analysis. Each drug was effective in reducing pyrexia when used alone. Log-dose-response curves of all the three drugs did not show any significant departure from parallelism indicating thereby, a common mode of antipyretic action. However, rofecoxib exhibited significantly higher potency than S-methylisothiourea. Isobolographic analysis of combination of S-methylisothiourea with rofecoxib and mefenamic acid revealed additive interaction. Experimental ED(50) of the combinations was not significantly different from theoretical additive ED(50) of the corresponding drug combination, that substantiated the additive nature of interaction between inducible nitric oxide synthase and cyclooxygenase in Brewer's yeast-induced fever in mice. Results suggest involvement of a mediator that is subservient to both inducible nitric oxide synthase and cyclooxygenase-2 enzyme activities. For further investigation, peroxynitrite ion may be considered to be the putative mediator.
authors.affiliation: Division of Pharmacology and Toxicology, Indian Veterinary Research Institute, Izatnagar, Bareilly, U.P. 243 122, India.
authors.forename: Abdul-Shakoor
authors.initials: AS
authors.lastname: Bhat
authors.forename: Surendra Kumar
authors.initials: SK
authors.lastname: Tandan
authors.forename: Dinesh
authors.initials: D
authors.lastname: Kumar
authors.forename: Vamsi
authors.initials: V
authors.lastname: Krishna
authors.forename: Vellanki Ravi
authors.initials: VR
authors.lastname: Prakash
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005334:Fever / Q000382:microbiology / Q000517:prevention & control*; D007550:Isothiuronium / Q000031:analogs & derivatives* / Q000494:pharmacology; D007783:Lactones / Q000494:pharmacology; D016014:Linear Models; D008297:Male; D008528:Mefenamic Acid / Q000494:pharmacology; D051379:Mice; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D011897:Random Allocation; D012441:Saccharomyces cerevisiae / Q000254:growth & development; D013450:Sulfones / Q000494:pharmacology; D016896:Treatment Outcome
chemical_list: D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D007783:Lactones; D013450:Sulfones; C116926:rofecoxib; D007550:Isothiuronium; D008528:Mefenamic Acid; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C027744:S-methylisothiopseudouronium