RESUMEN

In a randomized, double-blind, placebo-controlled, four-way crossover study, possible influences of the triple therapy with amoxicillin, clarithromycin and the proton pump inhibitor lansoprazole on the pharmacokinetics of each of the drugs and the active 14-OH-clarithromycin metabolite were assessed. Twelve Helicobacter pylori-negative healthy male volunteers (age 27 +/- 4.3 years; creatinine clearance 7.0 +/- 2.0 L/h) were given lansoprazole 30 mg, amoxicillin 1 g and clarithromycin 500 mg, alone and in triple combination. Drug elimination intervals were at least 9 days between the dosing periods. The study medication was administered twice daily for 4 days. On the fifth day of each period, drugs were only given once in the morning, and blood and urine samples were collected for 12 h. The concentrations of the three substances administered, and 14-OH-clarithromycin, were determined by validated HPLC methods. Alterations in the serum kinetics were found for lansoprazole and the active 14-OH-clarithromycin metabolite (all data expressed as mean +/- S.D.). For lansoprazole, the elimination half-life (t(1/2)) was significantly prolonged (1.46 versus 1.7 h, P < 0.05) and the area under the concentration-time curve from 0 to 8 h (AUC(0-8)) was significantly increased (3.65 versus 4.59 mg.h/L, P < 0.05) by combination of the drugs. For 14-OH-clarithromycin, the peak concentration (C(max)) was 0.95 versus 1.18 mg/L and the AUC from 0 to 12 h (AUC(0-12)) was 8.3 versus 10.5 mg.h/L (augmented significantly, P < 0.05). The amoxicillin concentrations were slightly elevated by concomitant administration of lansoprazole and clarithromycin but without statistical significance (11.1 versus 12.6 mg/L). For clarithromycin, the time to maximum concentration of drug in serum (T(max)) was increased (2.73 versus 3.31 h, P < 0.05), whereas AUC and C(max) remained unchanged. Simultaneous administration of lansoprazole, amoxicillin and clarithromycin increases the serum concentrations of lansoprazole and the active 14-OH-clarithromycin metabolite significantly. These effects were not so pronounced as to have any therapeutic influence, making dosage adjustment unnecessary.

Asunto(s)

Amoxicilina/farmacocinética , Claritromicina/farmacocinética , Quimioterapia Combinada/farmacocinética , Omeprazol/farmacocinética , 2-Piridinilmetilsulfinilbencimidazoles , Adulto , Amoxicilina/administración & dosificación , Amoxicilina/sangre , Amoxicilina/orina , Área Bajo la Curva , Claritromicina/administración & dosificación , Claritromicina/sangre , Claritromicina/orina , Intervalos de Confianza , Estudios Cruzados , Método Doble Ciego , Interacciones Farmacológicas/fisiología , Quimioterapia Combinada/administración & dosificación , Quimioterapia Combinada/sangre , Quimioterapia Combinada/orina , Humanos , Lansoprazol , Masculino , Omeprazol/administración & dosificación , Omeprazol/análogos & derivados , Omeprazol/sangre , Omeprazol/orina

RESUMEN

OBJECTIVE: To investigate changes in fecal flora and multiple-dose pharmacokinetics with the oral antibiotics ceftibuten 400 mg daily and cefpodoxime proxetil (CPX) 200 mg every 12 h, compared to amoxycillin/clavulanate 500/125 mg every 8 h during and following 1 week of medication. METHODS: In an open randomized triple crossover design, 18 (nine female, nine male) healthy volunteers received each drug for 7 days, followed by a 'washout' period of 4 weeks. Serum and urine levels of the substances were determined by bioassay, and for ceftibuten isomers by high-pressure liquid chromatography. Statistical analysis of quantitative aerobic and anaerobic cultures of feces was performed, and beta-lactamase activity was determined. RESULTS: Ceftibuten showed a mean Cmax of 18.9 (SD 3.0) mg/L, a terminal half-life of 2.89 h, and an AUCtot of 100 (21.8) mg.h/L; protein binding was 63.7 (5.1)%, and accumulation was marginal. Cefpodoxime proxetil had a Cmax of 1.92 (0.61) mg/L, a terminal half-life of 1.97 (0.42) h and an AUCtot of 10.8 (3.3) mg.h/L; no accumulation was seen. Amoxycillin and clavulanate had Cmax values of 7.15 (2.16) mg/L and 3.39 (1.31) mg/L, terminal half-life values of 1.03 (0.15) h and 0.93 (0.17) h, AUCtot values of 20.0 (4.2) mg.h/L and 8.87 (3.10) mg.h/L, and there was no accumulation. Statistical analysis for ech microorganism in fecal samples showed significant differences between amoxycillin/clavulanate and the two third-generation cephalosporins, but virtually no differences between ceftibuten and cefpodoxime proxetil. Eleven of 12 volunteers reported loose stools (days 2-7, mean duration 4.4 (SD 2.7) days) with amoxycillin/clavulanate, but nobody during ceftibuten administration and one volunteer during cefpodoxime proxetil administration. CONCLUSIONS: Ceftibuten showed excellent and cefpodoxime favorable pharmacokinetic properties, with significantly less pronounced fecal flora changes and intestinal side effects compared to amoxycillin/clavulanate. The multiple crossover design allows powerful microbiological statistical analysis and pharmacokinetic parameter comparisons.

RESUMEN

OBJECTIVE: To evaluate the pharmacokinetics of cefetamet pivoxil and possible interaction with N-acetylcysteine and cisapride in healthy volunteers. METHODS: In a double-blind, randomized three-way crossover study with 12 healthy male volunteers, serum and urine concentrations of cefetamet were determined over 12 h by a validated bioassay method after oral administration of 0.5 g cefetamet pivoxil and, randomly, placebo, 5x20 mg cisapride, or 0.6 g N-acetylcysteine. RESULTS: The study medications were well tolerated, although there were 10 cases of altered bowel movements, two cases of mild, transient headache and one case of increased serum transferase levels (AST and ALT). The mean peak serum level of cefetamet pivoxil in the placebo group was 4.86plus minus1.35 mg/L. The urine recovery/24 h in the placebo group was 41.9plus minus3.8% of the oral dose. The elimination half-life was 3.56plus minus0.92 h. N-Acetylcysteine had no effect on the pharmacokinetics of cefetamet pivoxil. With concomitant administration of cisapride there was an accelerated absorption of cefetamet pivoxil and a slightly increased Cmax of cefetamet. The Cmax values differed significantly (p<0.05) only between the cisapride group (5.76plus minus1.50 mg/L) and the N-acetylcysteine group (4.53plus minus1.18 mg/L). CONCLUSION: None of the small pharmacokinetic differences between the three groups is expected to have any relevance in the treatment of infectious diseases with cefetamet pivoxil.

RESUMEN

OBJECTIVES: The pharmacokinetics of macrolide antibiotics --- erythromycin (ER), clarithromycin (CL), roxithromycin (RO), azithromycin (AZ), dirithromycin (DI) and the concentrations achieved in polymorphonuclear neutrophils (PMNs) and saliva were investigated. METHODS: In a four-way crossover trial, 10 healthy volunteers received 1000 mg ER twice a day, 500 mg CL twice a day, 150 mg RO twice a day and 500 mg AZ every day over a period of 3 days. In a second trial, 10 healthy volunteers received 500 mg DI every day over a period of 5 days. Concentrations of these antibiotics were measured in serum, urine, saliva and PMNs by high-performance liquid chromatography (HPLC) on days 1 and 3 in the first trial and on days 1 and 5 in the second trial. RESULTS: We found considerable differences in the pharmacokinetics, not only in serum, but also in PMNs and saliva. All substances except RO exhibited higher concentrations in PMNs than in serum, indicating excellent intraphagocytic distribution. In contrast, concentrations in saliva were lower than those measured in serum, with the exception of AZ. ER is characterized by low serum concentrations and moderate concentrations in saliva and PMNs. CL reached considerable concentrations in serum, saliva and PMNs. RO achieved the highest serum levels, but concentrations in saliva and in PMNs were below the detection limit. In contrast, AZ and DI yielded the lowest serum concentrations and the highest saliva and PMN concentrations. CONCLUSIONS: Our data emphasize the importance of tissue distribution, in addition to serum kinetics, in evaluating the pharmacokinetic profiles of antibiotics.