Chapter 8
- Metabolism and Toxicity of Modern Inhaled Anesthetics
- Jackie L. Martin Jr.
- Dolores B. Njoku
After a drug is administered, it undergoes the processes of absorption,
distribution, target interaction, metabolism, and excretion. Unlike most drugs,
inhaled anesthetics are administered in great excess of the amount metabolized.
Biotransformation has little effect on the pharmacologic activity of anesthetics
but may have a significant effect on anesthetic toxicities. It was once thought
that the inhaled anesthetics were chemically inert, but many of these anesthetic
agents undergo significant metabolism and, in many cases, biotransformation and chemical
breakdown to reactive and potentially toxic intermediates. The metabolic processes
are affected by many factors, including age, disease, drug-drug interactions, and
perhaps most importantly, genetics. This chapter focuses on the current understanding
of mechanisms of anesthetic associated toxicities, particularly liver injury and
the role of drug metabolism in many of these processes. The clinical mechanisms,
implications, and risks of haloalkene- and carbon monoxide-associated toxicities,
as well as other side effects of inhaled anesthetics, are reviewed.
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