Document Detail

Cigarette smoking and theophylline clearance and metabolism.
MedLine Citation:
PMID:  7285483     Owner:  NLM     Status:  MEDLINE    
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.
J J Grygiel; D J Birkett
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Clinical pharmacology and therapeutics     Volume:  30     ISSN:  0009-9236     ISO Abbreviation:  Clin. Pharmacol. Ther.     Publication Date:  1981 Oct 
Date Detail:
Created Date:  1981-12-22     Completed Date:  1981-12-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372741     Medline TA:  Clin Pharmacol Ther     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  491-6     Citation Subset:  AIM; IM    
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MeSH Terms
Cytochrome P-450 Enzyme System / metabolism
Metabolic Clearance Rate
Theophylline / metabolism*
Uric Acid / analogs & derivatives,  metabolism
Xanthines / metabolism
Reg. No./Substance:
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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