Combined paracetamol and amitriptyline adsorption to activated charcoal

Abstract

Objectives. High-gram drug doses seen in multiple-drug poisonings might be close to the adsorption capacity of activated charcoal (AC). The aim was to determine the maximum adsorption capacities (Q_m) of amitriptyline and paracetamol, separately and in combination, to AC. Methods. ACs (Carbomix® and Norit Ready-To-Use) were tested in vitro. At pH 1.2 and pH 7.2, 0.250 g AC and paracetamol and/or amitriptyline were mixed and incubated. The AC : drug ratios were 10 : 1, 5 : 1, 3 : 1, 2 : 1, and 1 : 1. The mixed-drug adsorption vials contained the same AC : paracetamol ratios, but amitriptyline was added as fixed dose (0.080 g) to all samples. Drug concentrations in the liquid phase were analyzed using high-performance liquid chromatography (HPLC)/UV-detection. Results. Q_m, amitriptyline, were 0.49 g/g Carbomix® and 0.70 g/g Norit Ready-To-Use, and Q_m, paracetamol, were 0.63 g/g Carbomix® and 0.72 g/g Norit Ready-To-Use. The tested pH differences had minor effect on the adsorption. The mixed-drug adsorption showed about 40% Q_m reduction of each drug with increasing amounts of drug/g AC, but the total gram of drug adsorbed to AC was increased compared to one-drug conditions. Conclusion. The adsorption of the two compounds to AC seems to compete resulting in lower maximum adsorption capacity for both drugs when mixed. However, a great adsorptive capacity was noted and might be explained by adsorption of the drugs to different AC surface sites. Furthermore, the Norit Ready-To-Use preparation, with less volume and total weight for the same AC dose as Carbomix®, showed a higher Q_m. This might be clinically significant in terms of preventing nausea, vomiting, and subsequent aspiration.

• Intoxication
• Analgesics
• Cyclic antidepressants
• Activated charcoal

Acknowledgments

The ACs, Carbomix® and Ready-To-Use, used in this study were kindly provided by Aage Christensen A/S, Valby, Denmark.

Declaration of interest

The authors report no declarations of interest. The authors alone are responsible for the content and writing of this paper.