Chinese Society of Critical Care Medicine-CSCCM 10th Anniversary

讲座摘要

POISONINGS AND ANTIDOTES

F Baud

Frédéric J Baud¹

¹Medical and Toxicological Critical Care Department. Assistance Publique–Hôpitaux de Paris ; Hôpital Lariboisière-Université Denis Diderot. Paris, France

Abstract

The treatment of poisoning includes supportive treatment, decontamination, and antidotes.

This classification masks the duality of human poisoning involving the combination of toxicokinetic and toxicodynamic processes.

All treatments used in toxicology can be classified within 8 categories including 5 modifying toxicokinetics and 3 modifying toxicodynamics of poisons.

The 5 ways to modify toxicokinetics include:

-1- decreasing the bioavailability of toxicants by non-specific (activated charcoal, skin or ocular washing, whole bowel irrigation) or specific agents (ex: calcium for fluoride, Prussian blue for Thallium)

-2- promoting the extra-cellular redistribution of the toxicants: specific Fab fragments for cardiac glycosides, methemoglobin-forming agents or hydroxocobalamin for cyanide

-3- promoting the elimination of the toxicant unchanged in the urine (alkaline dieresis for salicylates, phenobarbital, glyphosate; chelating agents for heavy metals) or in the breath (oxygen and carbon monoxide)

-4- increasing the metabolism resulting in inactive metabolites: N-acetylcystein for paracetamol, sodium thiosulfate for cyanide, carboxypeptidase for methotrexate, L-carnithine for valproate

-5- blocking a metabolism resulting in active metabolites: fomepizole for toxic alcohols

The 3 ways modifying toxidynamics include:

-6- non competitive (pralidoxime in organophosphates), or competitive antagonism (antagonists: naloxone, flumazénil, atropine, catecholamines, …)

-7- by pass of the binding of the toxicant to the receptor/target (glucagon and beta-blockers, insulin and calcium channel inhibitors)

-8- correcting the peripheral effects of the toxicants (dextrose for insulin, calcium to correct fluoride-induced hypocalcaemia, mechanical ventilation to support drug-induced respiratory failure, cardiovascular support in drug-induced cardiovascular shock)

Decontamination aimed at decreasing the bioavailability of toxic substances; there are accumulating evidence of its efficiency during a very short period of time.

Supportive treatment efficiently corrects the peripheral effects of the toxicants.

Supportive treatment may correct failure of organ involved in the elimination of substances.

In this condition, supportive treatment is also a toxicokinetic treatment.

The number of antidotes obviating or decreasing the need for supportive therapy is progressively growing.

第二届中法危重病医学研讨会暨上海重症医学论坛（2009年12月中国上海）