{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,16]],"date-time":"2025-10-16T20:27:05Z","timestamp":1760646425282},"reference-count":0,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2016,2,17]],"date-time":"2016-02-17T00:00:00Z","timestamp":1455667200000},"content-version":"vor","delay-in-days":13288,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Clin Pharma and Therapeutics"],"published-print":{"date-parts":[[1979,10]]},"abstract":"<jats:p>The metabolism and kinetics of <jats:sup>14<\/jats:sup>C\u2010labeled theophylline have been studied after intravenous doses of 100 mg to healthy subjects, keeping to their usual diets after 7 days of abstention from methylxanthine\u2010containing foods and beverages and again after such abstention while taking caffeine and theophylline in tablet form. The metabolism of oral <jats:sup>14<\/jats:sup>C\u2010theophylline has also been investigated. Metabolites were separated and quantitated by ion\u2010exchange column chromatography, ion\u2010exchange paper chromatography, and liquid scintillation counting. Three major metabolites were found in urine in addition to theophylline, namely 3\u2010methylxanthine, 1.3\u2010dimethyluric acid, and 1\u2010methyluric acid, and 2 minor metabolites were detected but not identified. The elimination kinetics were studied after intravenous administration; theophylline, 1.3\u2010dimethyluric acid, and 1\u2010methyluric acid were eliminated by first\u2010order processes, while elimination of 3\u2010methylxanthine was described by Michaelis\u2010Menten kinetics. Abstention from methylxanthine\u2010containing foods and beverages led to a significant decrease in the urinary elimination half\u2010life of <jats:sup>14<\/jats:sup>C from 9.8 to 7.0 hr (p &lt; 0.02) due to increases in the elimination constants for theophylline, 3\u2010methylxanthine, and 1,3\u2010ldimethyluric acid. When the methylxanthine content of the methylxanthine\u2010containing foods and beverages was replaced by caffeine and theophylline in tablet form, kinetics and metabolism of theophylline were the same as in subjects on usual diets.<\/jats:p>","DOI":"10.1002\/cpt1979264513","type":"journal-article","created":{"date-parts":[[2016,1,5]],"date-time":"2016-01-05T17:13:12Z","timestamp":1452013992000},"page":"513-524","source":"Crossref","is-referenced-by-count":88,"title":["Influence of methylxanthine\u2010containing foods on theophylline metabolism and kinetics"],"prefix":"10.1111","volume":"26","author":[{"given":"Terrence J.","family":"Monks","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"John","family":"Caldwell","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Robert L.","family":"Smith","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2016,2,17]]},"container-title":["Clinical Pharmacology &amp; Therapeutics"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Fcpt1979264513","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Fcpt1979264513","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/ascpt.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/cpt1979264513","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,11,7]],"date-time":"2023-11-07T13:33:53Z","timestamp":1699364033000},"score":1,"resource":{"primary":{"URL":"https:\/\/ascpt.onlinelibrary.wiley.com\/doi\/10.1002\/cpt1979264513"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1979,10]]},"references-count":0,"journal-issue":{"issue":"4","published-print":{"date-parts":[[1979,10]]}},"alternative-id":["10.1002\/cpt1979264513"],"URL":"https:\/\/doi.org\/10.1002\/cpt1979264513","archive":["Portico"],"relation":{},"ISSN":["0009-9236","1532-6535"],"issn-type":[{"value":"0009-9236","type":"print"},{"value":"1532-6535","type":"electronic"}],"subject":[],"published":{"date-parts":[[1979,10]]}}}