Poisoning anesthetic agents

Some anesthetics are either too irritating or too ineffective to be applied to the eye. However, they are useful as topical anesthetic agents on the skin and/or mucous membranes. These preparations are effective in the symptomatic relief of anal and genital pruritus, poison ivy rashes, and numerous... 

Toxic agents cause injuries in different ways and have been categorized into seven types (see Figure 5-1) asphyxiates, irritants, systemic poisons, anesthetics, neurotics, corrosives, and carcinogens. 

The method of drug administration or exposure to a poison may impart selectivity to a xenbiotic. For example, atropine can be applied directly to the eye for the dilation of the pupils. Note that eventual absorption into the blood stream from this site will cause systemic effects. Another example would be the topical (skin) application of a local anesthetic such as benzocaine. Monoclonal antibodies, which are specific for chemical functional groups, are tissue and cell-specific natural agents to which drugs can be chemically bonded. 

Research on anesthetic gases during the nineteenth century facilitated the development and use of poisonous war gases in the twentieth. This led to attempts to counteract the effects of chemical warfare agents and other toxic compounds, particularly arsenicals, introduced by Paul Ehrlich (1854-1915) for the treatment of syphilis. This resulted in the synthesis of the first specific chemical antidote, British anti-Lewisite (BAL), in 1945 by R.A. Peters, L.A. Stocken, and R.H.S. Thompson in Oxford. Studies on the mechanistic bases for toxicity were applied to the synthesis of effective insecticides. For example, during the 1940s, the Swiss chemist Paul Muller discovered a compound, now known as DDT, that poisons insects on contact. 

Poisoning by cocaine is rare, and the chief forensic interest in this compound is as a drug of addiction. At one time, however, it was a fairly common suicidal agent. As a local anesthetic it has now been almost completely replaced by synthetic compounds such as procaine and ligno-caine which are without addictive properties, and whose toxicity, though by no means negligible, is considerably less than that of cocaine (97). 

Two well-known alkaloids, cocaine (3.11) and atropine (3.12), are ester derivatives of the 8-azabicyclo[3.2.1]octane ring system. Cocaine, isolated from a variety of the poppy plant, has been used as a topical anesthetic, but it is highly addictive if it enters the bloodstream and is now a controlled substance. Atropine, however, is highly useful in medicine with anticholinergic properties. It is isolated from the Belladonna plant and has been used for many years to dilate the pupil of the eye. It is also an effective antidote to poisoning by anticholinesterase chemicals, when these are used as insecticides or in extremely toxic form as chemical warfare agents. 

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