Anesthetic agents, pharmacologic properties

Methoxyflurane (Penthmne) is the most potent inhala-tional agent available, but its high solubility in tissues limits its use as an induction anesthetic. Its pharmacological properties are similar to those of halothane with some notable exceptions. For example, since methoxyflurane does not depress cardiovascular reflexes, its direct myocardial depressant effect is partially offset by reflex tachycardia, so arterial blood pressure is better maintained. Also, the oxidative metabolism of methoxyflurane results in the production of oxalic acid and fluoride concentrations that approach the threshold of causing renal tubular dysfunction. Concern for nephrotoxicity has greatly restricted the use of methoxyflurane. 

Todorovic SM, Lingle CJ (1998) Pharmacological properties of T-type Ca current in adult rat sensory neurons effects of anticonvulsant and anesthetic agents. J Neuro-phys 79 240-252... 

Chen G, Ensor CR, Bohner B (1966) The neuropharmacology of 2-(o-chlorophenyl)-2-methylaminocyclohexanone hydrochloride. J Pharm Exp Ther 152 332-339 Child KJ, Currie JP, Davis B et al. (1971) The pharmacological properties in animals of CT1341 - a new steroid anaesthetic agent. Br J Anaesth 43 2-24 Christensen HD, Lee IS (1973) Anesthetic potency and acute toxicity of optically active di-substituted barbituric acids. Toxicol Appl Pharmacol 26 495-503 Domenjoz R (1959) Anaesthesist 8 16... 

Ixxtal anesthetics do not rely on blood circulation to reach their site of action, as they are usually administered at. or close to. their site of action. Systemic side effects ari.se be-caiLse the local anesthetic agent is carried away in the blood hefure it can be fully metabolized. Con.sequently. the chemi-ciil iind pharmacological properties of local anesthetics arc of major importance in determining not only the effectiveness of the drug but also its systemic. side effects. 

The challenge at hand is to achieve optimal patient comfort while avoiding the risks of oversedation and respiratory depression. The type of local anesthetic and the dose delivered are important in addition to appropriate conscious sedation. As a general rule, it is desirable to select an anesthetic agent that is rapid in onset in combination with one that offers sustained action. A list of pharmacologic properties of commonly used local anesthetic agents is found in Table 4.6. 

Table 4.6 Pharmacologic properties of commonly used local anesthetic agents.

General Anesthetics - Although there were many reports concerning the pharmacological and clinical properties of previously reported agents, little was published during 1967 which constitutes an appreciable advance in this area of medicinal chemistry. 

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