| Cigarette smoking and theophylline clearance and metabolism. | |
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MedLine Citation:
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PMID: 7285483 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Differences in plasma theophylline clearance (ClT) and metabolism between smoking and nonsmoking normal subjects were examined by analysis of plasma and urinary theophylline concentrations and of urinary metabolite concentrations under steady-state oral dosing conditions. ClT in smokers (0.053 +/- 0.006 1 . hr-1 . kg-1) was greater than in nonsmokers (0.032 +/- 0.002 l . hr-1 . kg-1, p less than 0.005). Analyses of urinary metabolites revealed that clearance to l-methyluric acid (Cl1MU) and clearance to 3-methylxanthine (Cl3MX) were increased in smokers 1.99-fold and 2.10-fold over nonsmoking controls (P less than 0.005). Clearance to 1.3-dimethyluric acid (ClDMU) was also enhanced in smokers 1.68-fold compared to controls (P less than 0.01). The positive relationship between Cl1MU and Cl3MX in both smokers and nonsmokers (r = 0.98, P less than 0.001) supports the concept that two N-demethylation pathways for theophylline metabolism are under common regulatory control and involve a form of cytochrome P450 distinct from that mediating 8-hydroxylation of theophylline to DMU. These results suggest that cigarette smoking induces both of the cytochrome P450-mediated pathways of theophylline metabolism but that N-demethylation may be increased to a greater extent than 8-hydroxylation. |
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Authors:
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J J Grygiel; D J Birkett |
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Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Clinical pharmacology and therapeutics Volume: 30 ISSN: 0009-9236 ISO Abbreviation: Clin. Pharmacol. Ther. Publication Date: 1981 Oct |
Date Detail:
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Created Date: 1981-12-22 Completed Date: 1981-12-22 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0372741 Medline TA: Clin Pharmacol Ther Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 491-6 Citation Subset: AIM; IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Biotransformation Cytochrome P-450 Enzyme System / metabolism Female Humans Male Metabolic Clearance Rate Smoking* Theophylline / metabolism* Uric Acid / analogs & derivatives, metabolism Xanthines / metabolism |
| Chemical | |
Reg. No./Substance:
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0/Xanthines; 28109-92-4/methylxanthine; 58-55-9/Theophylline; 69-93-2/Uric Acid; 708-79-2/1-methyluric acid; 9035-51-2/Cytochrome P-450 Enzyme System; 944-73-0/1,3-dimethyluric acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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