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Effect of indomethacin on arachidonic acid metabolism in human leukocytes stimulated ex vivo
Author(s) -
Docherty John C,
Wilson Thomas W
Publication year - 1991
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.1991.31
Subject(s) - arachidonic acid , leukotriene b4 , cyclooxygenase , lipoxygenase , chemistry , thromboxane b2 , leukotriene , in vivo , ex vivo , pharmacology , metabolism , platelet , eicosanoid , in vitro , ionophore , endocrinology , calcium , biochemistry , medicine , enzyme , inflammation , biology , asthma , microbiology and biotechnology , organic chemistry
We had previously shown that inhibition of cyclooxygenase in vitro by indomethacin can cause increased formation of products of the 5‐lipoxygenase pathway of arachidonic acid metabolism in leukocytes. To determine if this effect also occurred in vivo, we studied leukocyte arachidonic acid metabolism in 12 volunteers before and after ingestion of 150 mg indomethacin daily for 3 days. Blood was collected before treatment and 2 hours, 2 days, and 5 days after the final dose of indomethacin. Serum thromboxane B 2 , a measure of platelet cyclooxygenase activity, was profoundly suppressed 2 hours after the final dose of indomethacin but had recovered to control values at 2 days. Mixed leukocyte suspensions and purified neutrophil suspensions were prepared and stimulated with calcium ionophore A23187 and the resultant 5‐lipoxygenase metabolites were quantified by HPLC. Two hours after the final dose of indomethacin, the stimulated levels of 5‐hydroxyeicosatetraenoic acid, leukotriene B 4 , and leukotriene C 4 were significantly increased to 247% ± 68%, 135% ± 14%, and 149% ± 23% of pretreatment values, respectively. Two days after the final dose of indomethacin, 5‐hydroxyeicosatetraenoic acid levels were still significantly elevated. By 5 days all parameters had returned to baseline. Similar effects were not observed in purified neutrophil suspensions, probably because of the loss of indomethacin from the cells during the multiple washing procedures used in their preparation. This is in accord with the reversible nature of the inhibitory effect of indomethacin on cyclooxygenase. We conclude that indomethacin at a commonly used dose increases the ability of circulating leukocytes to produce 5‐lipoxygenase products. Clinical Pharmacology and Therapeutics (1991) 49, 294–299; doi: 10.1038/clpt.1991.31