PREVENTION OF AMLODIPINE ABSORPTION BY ACTIVATED-CHARCOAL - EFFECT OFDELAY IN CHARCOAL ADMINISTRATION

Aims The purpose of this study was to investigate the effect of activa ted charcoal on the absorption of amlodipine, with special reference t o delayed charcoal administration. Methods Thirty-two healthy voluntee rs, eight subjects in four parallel groups, ingested 10 mg of amlodipi ne on an empty stomach. Activated charcoal (25 g in 300 ml of water) w as ingested either immediately afterwards or 2 h or 6 h after amlodipi ne, or amlodipine was ingested with 300 mi of water only (control). Pl asma concentrations and the cumulative excretion of amlodipine into ur ine were measured by GC-MS for 96 h and 72 h, respectively. In additio n, adsorption of amlodipine to charcoal was studied in vitro. Results Activated charcoal administered immediately after amlodipine reduced t he amlodipine AUC(0,96 h) and the 72-h urinary excretion by 99% (P<0.0 005). After a delay of 2 h in charcoal administration the AUC(0,96 h) was reduced by 49% (P=0.001), but after a delay of 6 h the reduction w as 15% only (P=NS). At a charcoal:drug ratio of 5:1, about 90% of amlo dipine was adsorbed by charcoal in vitro; at ratios of 10:1 and 20:1, adsorption was practically complete. Conclusions Activated charcoal al most completely prevented amlodipine absorption when administered imme diately after amlodipine ingestion. Charcoal also markedly reduced aml odipine absorption when given 2 h after amlodipine; in amlodipine over dose, administration of charcoal may be beneficial even later. We conc lude that administration of activated charcoal is the method of choice to prevent absorption of amlodipine in amlodipine overdose.