RESUMEN
The present study investigates the isoform(s) of cytochrome P450 (CYP) involved in the metabolism of albendazole sulfoxide (ASOX) to albendazole sulfone (ASON) in patients with neurocysticercosis using antipyrine as a multifunctional marker drug. The study was conducted on 11 patients with neurocysticercosis treated with a multiple dose regimen of albendazole for 8 days (5 mg/kg every 8 h). On the 5th day of albendazole treatment, 500 mg antipyrine was administered po. Blood and urine samples were collected up to 72 h after antipyrine administration. Plasma concentrations of (+)-ASOX, (-)-ASOX and ASON were determined by HPLC using a chiral phase column and detection by fluorescence. The apparent clearance (CL/f) of ASON and of the (+) and (-)-ASOX enantiomers were calculated and compared to total antipyrine clearance (CL T) and the clearance for the production of the three major antipyrine metabolites (CLm). A correlation (P<=0.05) was obtained only between the CL T of antipyrine and the CL/f of ASON (r = 0.67). The existence of a correlation suggests the involvement of CYP isoforms common to the metabolism of antipyrine and of ASOX to ASON. Since the CL T of antipyrine is a general measure of CYP enzymes but with a slight to moderate weight toward CYP1A2, we suggest the involvement of this enzyme in ASOX to ASON metabolism in man. The study supports the establishment of a specific marker drug of CYP1A2 in the study of the in vivo metabolism of ASOX to ASON
Asunto(s)
Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Albendazol , Antihelmínticos , Antiinflamatorios no Esteroideos , Antipirina , Sistema Enzimático del Citocromo P-450 , Neurocisticercosis , Albendazol , Antihelmínticos , Antiinflamatorios no Esteroideos , Antipirina , Biomarcadores , Sistema Enzimático del Citocromo P-450 , Interacciones Farmacológicas , Isoenzimas , NeurocisticercosisRESUMEN
We describe a new simple, selective and sensitive micromethod based on HPLC and fluorescence detection to measure debrisoquine (D) and 4-hydroxydebrisoquine (4-OHD) in urine for the investigation of xenobiotic metabolism by debrisoquine hydroxylase (CYP2D6). Four hundred µl of urine was required for the analysis of D and 4-OHD. Peaks were eluted at 8.3 min (4-OHD), 14.0 min (D) and 16.6 min for the internal standard, metoprolol (20 µg/ml). The 5-µm CN-reverse-phase column (Shimpack, 250 x 4.6 mm) was eluted with a mobile phase consisting of 0.25 M acetate buffer, pH 5.0, and acetonitrile (9:1, v/v) at 0.7 ml/min with detection at lexcitation = 210 nm and lemission = 290 nm. The method, validated on the basis of measurements of spiked urine, presented 3 ng/ml (D) and 6 ng/ml (4-OHD) sensitivity, 390-6240 ng/ml (D) and 750-12000 ng/ml (4-OHD) linearity, and 5.7/8.2 percent (D) and 5.3/8.2 percent (4-OHD) intra/interassay precision. The method was validated using urine of a healthy Caucasian volunteer who received one 10-mg tablet of Declinax®, po, in the morning after an overnight fast. Urine samples (diuresis of 4 or 6 h) were collected from zero to 24 h. The urinary excretion of D and 4-OHD, Fel (0-24 h), i.e., fraction of dose administered and excreted into urine, was 6.4 percent and 31.9 percent, respectively. The hydroxylation capacity index reported as metabolic ratio was 0.18 (D/4-OHD) for the person investigated and can be compared to reference limits of < 12.5 for poor metabolizers (PM) and < 12.5 for extensive metabolizers (EM). In parallel, the recovery ratio (RR), another hydroxylation capacity index, was 0.85 (4-OHD: SD + 4-OHD) versus reference limits of RR < 0.12 for PM and RR > 0.12 for EM. The healthy volunteer was considered to be an extensive metabolizer on the basis of the debrisoquine test.
Asunto(s)
Humanos , Femenino , Persona de Mediana Edad , Cromatografía Líquida de Alta Presión/métodos , Citocromo P-450 CYP2D6/metabolismo , Debrisoquina/orina , Intervalos de Confianza , Debrisoquina/metabolismo , Población Blanca , Fluorometría/métodos , Hidroxilación , Fenotipo , Sensibilidad y EspecificidadRESUMEN
A method which permits the simultaneous HPLC analysis of antipyrine (A), 3-hydroxymethylantipyrine (HMA), 4-hydroxyantipyrine (HOA) and norantiopyrine (NORA) using a single extraction step in a five minute chromatographic run is described. Only 500 micraLitro of urine were necessary for the quantitation of all compounds investigated. An analog derivative, 4-aminoantipyrine, was used as internal standard (IS). Urine samples were hydrolyzed with Limpet acetone powder, 37 graus centigrados, pH 5.0 for 2 h. Sodium chloride was added and urine samples were extracted with diclhormethane-isopropyl alcohol (90:10, v/v) in acidic medium. The residue was dissolved with mobile phase, washed with n-hexane and 20 micralitro of the lower phase were injected into a 4-micron Nova-Pak (R) 'C IND. 18' column. Peaks monitored at 254 nm were eluted with 0.75 M sodium acetate buffer, pH 5.0: methanol, (70:30, v/v) as mobile phase. The method, validated on the basis of the confidence limits for antipyrine and its metabolites, presented good stability, sensitivity, linearity, and intra or interassay precisions lower than 5 percente for all commpounds were investigated. This assay was applied for drug metabolism study carried out in ten healthy volunteers: 23 about 5 yr and 63 about 10 kg(mean about SD) after p.o. single dose of antipyrine, 500 mg/capsule. Diuresis of 24 h up to 72 h of drug administration was preserved with sodium metabisulfite, 4 mg/mL. Biological fluids were stored at -20 centigrade degree until assay. The main hydroxy-metabolites (HMA + HOA) and NORA, minor N-demethylated metabolite of antipyrine, were excreted: 60 percent and 20 percente as percentage of the given dose, respectively. Clearances for production of metabolites expressed as mL/min, were: 8.61 about 4.28 (7.24) for HMA, 13.91 about 6.20(12.67) for HOA, and 8.08 about 4.01(5.93) for NORA, mean about SD (median).