Metabolism of isbufylline in humans. Isolation, identification, and synthesis of plasma and urine metabolites.
Isbufylline metabolism after oral administration to humans was studied. The main metabolites detected by the HPLC method, in plasma, were 1-methyl-7-(2-hydroxy-2-methyl-propyl) xanthine (I), 1,3-dimethyl-7-(2-hydroxy-2-methyl-propyl) xanthine (II), and 1-methyl-7-(2-methyl-propyl) xanthine (III). The main metabolites detected in urine were 1-methyl-7-(2-hydroxy-2-methyl-propyl) xanthine (I), 1,3-dimethyl-7-(2-carboxy-propyl) xanthine (IV), and 1,3-dimethyl-7-(2-hydroxymethyl-propyl) xanthine glucuronic acid (V)-Gluc. They were isolated by HPLC, identified by GC/MS, HPLC/MS, or HPLC/MS/MS, and finally synthesized. Recovery of these metabolites, along with the absence of unmetabolized isbufylline in the urine, indicated biotransformation and renal excretion as the main routes of isbufylline elimination in humans. HPLC quantitation of the characterized urine metabolites revealed that 49% of the drug was eliminated as (I), 9% as (V)-Gluc, and 5% as (IV).
Agostini
O
O
Analytical and Chemical Department, Istituto Farmacobiologico Malesci S.p.A., Florence, Italy.
Bonacchi
G
G
Coppini
G
G
Toja
E
E
Triolo
A
A
Manzini
S
S
Pieraccini
G
G
Moneti
G
G
D015056:1-Methyl-3-isobutylxanthine / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics / Q000652:urine; D000284:Administration, Oral; D001711:Biotransformation; D001993:Bronchodilator Agents / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D006868:Hydrolysis; D007202:Indicators and Reagents; D008297:Male; D013058:Mass Spectrometry
D001993:Bronchodilator Agents; D007202:Indicators and Reagents; C058878:isbufylline; D015056:1-Methyl-3-isobutylxanthine