{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,28]],"date-time":"2026-04-28T23:05:29Z","timestamp":1777417529369,"version":"3.51.4"},"reference-count":16,"publisher":"SAGE Publications","issue":"12","license":[{"start":{"date-parts":[[1992,12,1]],"date-time":"1992-12-01T00:00:00Z","timestamp":723168000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Ann Pharmacother"],"published-print":{"date-parts":[[1992,12]]},"abstract":"<jats:sec>\n                    <jats:title>OBJECTIVE:<\/jats:title>\n                    <jats:p>This study investigated a new, nonimmunologic, enzymatic-based theophylline assay for the possible interference of a clinically achievable serum theophylline concentration by four xanthine-related compounds: pentoxifylline, 1-methylxanthine, allopurinol, and oxypurinol.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>RATIONALE:<\/jats:title>\n                    <jats:p>The enzyme theophylline oxidase is used in this assay kit to convert theophylline to 1,3 dimethyluric acid in the presence of cytochrome C. Cytochrome C is reduced to ferrocyte C, which is then measured by ultraviolet spectrophotometry at one minute and again at five minutes. The rate of appearance of ferrocyte C over this time is then related to a one-point 20-\u03bcg\/mL (111-\u03bcmol\/L) theophylline standard provided with the kit and the concentration of theophylline is calculated. Xanthine-related compounds have the potential to interact with theophylline oxidase via: (1) structural similarity, and (2) inhibition of xanthine oxidase, which increases theophylline metabolite concentrations.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>DESIGN:<\/jats:title>\n                    <jats:p>Human serum was spiked with known, therapeutically achievable concentrations of pentoxifylline, 1-methylxanthine, allopurinol, and oxypurinol, both alone and in combination with theophylline in a concentration of 15 \u03bcg\/mL (83.3 \u03bcmol\/L). Two controls were used: human serum and human serum spiked with theophylline. Data were analyzed statistically with ANOVA, and clinically with \u00b110 percent control criteria.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>RESULTS:<\/jats:title>\n                    <jats:p>Means (\u00b1 SEM) for the control samples were 2.0 (0.2) \u03bcg\/mL for serum alone and 15.3 (0.3) \u03bcg\/mL for theophylline-spiked serum. For the test specimens, the results ranged from 2.3 to 2.8 \u03bcg\/mL and from 13.9 to 16.6 \u03bcg\/mL when xanthine-related compounds were added to serum without and with theophylline, respectively.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>CONCLUSIONS:<\/jats:title>\n                    <jats:p>The results were not statistically or clinically significant for the four xanthine-related compounds at the concentrations studied.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1177\/106002809202601217","type":"journal-article","created":{"date-parts":[[2017,1,13]],"date-time":"2017-01-13T15:24:47Z","timestamp":1484321087000},"page":"1576-1579","source":"Crossref","is-referenced-by-count":5,"title":["Effect of Xanthine-Related Compounds on a Theophylline Assay Using Theophylline Oxidase"],"prefix":"10.1177","volume":"26","author":[{"given":"Leigh M.","family":"Vaughan","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Andrew","family":"Gottehrer","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"179","published-online":{"date-parts":[[1992,12,1]]},"reference":[{"key":"bibr-bibr1-106002809202601217","first-page":"1105","volume-title":"Applied pharmacokinetics: Principles of therapeutic drug monitoring","author":"Hendeles L","year":"1986","edition":"2"},{"key":"bibr-bibr2-106002809202601217","doi-asserted-by":"publisher","DOI":"10.1177\/106002808602000204"},{"key":"bibr-bibr3-106002809202601217","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(86)90655-0"},{"key":"bibr-bibr4-106002809202601217","volume-title":"GDS enzymatic theophylline reagent","year":"1988"},{"key":"bibr-bibr5-106002809202601217","first-page":"1039","volume":"36","author":"Gupta SK","year":"1990","journal-title":"Clin Chem"},{"key":"bibr-bibr6-106002809202601217","first-page":"1014","volume":"37","author":"Rogers LC","year":"1991","journal-title":"Clin Chem"},{"key":"bibr-bibr7-106002809202601217","doi-asserted-by":"publisher","DOI":"10.1002\/cpt1979265660"},{"key":"bibr-bibr8-106002809202601217","first-page":"2717","volume":"42","author":"Cummings DM","year":"1985","journal-title":"Am J Hosp Pharm"},{"key":"bibr-bibr9-106002809202601217","first-page":"342","volume":"11","author":"Murrel GAC","year":"1986","journal-title":"Clin Pharmacokinet"},{"key":"bibr-bibr10-106002809202601217","volume-title":"Allopurinol. DRUGDEX information system","author":"DRUGDEX Editorial Staff."},{"key":"bibr-bibr11-106002809202601217","doi-asserted-by":"publisher","DOI":"10.1093\/clinchem\/29.9.1698"},{"key":"bibr-bibr12-106002809202601217","doi-asserted-by":"publisher","DOI":"10.1038\/clpt.1981.36"},{"key":"bibr-bibr13-106002809202601217","doi-asserted-by":"publisher","DOI":"10.1002\/cpt1976193375"},{"key":"bibr-bibr14-106002809202601217","doi-asserted-by":"publisher","DOI":"10.1002\/cpt1979265660"},{"key":"bibr-bibr15-106002809202601217","doi-asserted-by":"publisher","DOI":"10.1203\/00006450-198104000-00003"},{"key":"bibr-bibr16-106002809202601217","first-page":"457","volume":"7","author":"Cohen IA","year":"1988","journal-title":"Clin Pharm"}],"container-title":["Annals of Pharmacotherapy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/106002809202601217","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/106002809202601217","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,28]],"date-time":"2026-04-28T11:05:03Z","timestamp":1777374303000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/10.1177\/106002809202601217"}},"subtitle":[],"editor":[{"given":"J. Daniel","family":"Robinson","sequence":"additional","affiliation":[],"role":[{"role":"editor","vocabulary":"crossref"}]}],"short-title":[],"issued":{"date-parts":[[1992,12]]},"references-count":16,"journal-issue":{"issue":"12","published-print":{"date-parts":[[1992,12]]}},"alternative-id":["10.1177\/106002809202601217"],"URL":"https:\/\/doi.org\/10.1177\/106002809202601217","relation":{},"ISSN":["1060-0280","1542-6270"],"issn-type":[{"value":"1060-0280","type":"print"},{"value":"1542-6270","type":"electronic"}],"subject":[],"published":{"date-parts":[[1992,12]]}}}