INHALATIONAL ANESTHETICS WITH THEIR PHARMACOKINETIC PROPERTIES

Inhalational anesthetics are the most common drugs used for providing general anesthesia for surgery. They are used to induce unconsciousness, amnesia and immobility. In search for ideal anesthetic gas there have been discovered many agents, but sadly the perfect inhalational drug has not been produced. The pharmacokinetics of inhalational anesthetics depends on their physical properties. The rate of uptake and elimination of the inhalational anesthetics from the alveoli in mainly depends on their blood solubility. The main driving force of absorption and distribution of the gas through the body is partial pressure gradient on both sides of each barrier in the gas flow, and the therapeutic effect of the gas depends of the partial pressure of the anesthetic in the brain. All inhalational anesthetics, with exception of nitrous oxide and xenon, are metabolized (in different degrees) in liver via cytochrome P450 enzymes. The potency of different inhalational anesthetics is expressed via minimum alveolar concentration, which is defined as concentration of the anesthetics that prevent movement in 50% of the patients in response to surgical incision under standard conditions. Nitrous oxide and volatile halogenated ethers (desflurane, isoflurane, sevoflurane) are examples of medical gases that are greenhouse gases with great impact to global warming. This article summarizes a brief historical timeline of the inhalational anesthetics, mechanisms of action, physical characteristics and pharmacokinetic properties of inhalational agents with a short overview of their toxicity and pollution of the environment.