ABSTRACT
This chapter provides a multitude of pharmacologic classes which are best grouped together as those which act on the central nervous system. Inhalation anesthetic agents dissolve in the blood at the level of the alveolar capillary for delivery to the site of action in the lipid-rich central nervous system. Upon intravenous injection, barbiturates cause rapid, reversible, and dose-dependent central nervous system depression that ranges from sedation to general anesthesia to euthanasia. Tranquilizers, sedatives, and narcotic analgesics depress the central nervous system, but differ in their mechanism of action. These drugs are marketed in aqueous solutions or as dry powders of the water soluble salts. Interactions between the barbiturates and other drugs are common. Anesthetic activity of barbiturates is enhanced when the drugs are displaced from albumin by phenylbutazone, steroids, or radiographic contrast medium. Neuromuscular blockade may also be achieved by the administration of nondepolarizing drugs. Absorption of the phenothiazines is erratic, and following absorption, these drugs are highly bound to plasma albumins.
