Pharmacological, Physiological, and Biochemical Effects

It should also be noted that a profound physiological disturbance such as prolonged anoxia may result in irreversible pathological damage to sensitive tissue. There are many different types of response within this category with a variety of mechanisms, and it is beyond 

This type of effect can occur in all tissues and is caused by a metabolic inhibitor such as azide or cyanide, which inhibits the electron transport chain. Inhibition of one or more of the enzymes of the tricarboxylic acid cycle such as that caused by fluoroacetate (Fig. 6.7) also results in inhibition of cellular respiration (for more details of cyanide and fluoroacetate see chap. 7). 

Excessive muscular blockade may be caused by compounds such as the cholinesterase inhibitors. Such inhibitors, exemplified by the organophosphate insecticides such as malathion (chap. 5, Fig. 12) (see also chap. 7) and nerve gases (e.g., isopropylmethylphosphonofluor-idate), cause death by blockade of respiratory muscles as a result of excess acetylcholine accumulation. This is due to inhibition of the enzymes normally responsible for the inactivation of the acetylcholine (see chap. 7). Respiratory failure may also result from the inhibition of cellular respiration by cyanide, for example, or central effects caused by drugs such as dextropropoxyphene. 

Toxic substances can interfere with normal neurotransmission in a variety of ways, either directly or indirectly, and cause various central effects. For example, cholinesterase inhibitors such as the organo phosphate insecticides cause accumulation of excess acetylcholine. The accumulation of this neurotransmitter in the CNS in humans after exposure to toxic insecticides leads to anxiety, restlessness, insomnia, convulsions, slurred speech, and central depression of the respiratory and circulatory centers. 

The induction of unconsciousness may be the result of exposure to excessive concentrations of toxic solvents such as carbon tetrachloride or vinyl chloride, as occasionally occurs in industrial situations (solvent narcosis). Also, volatile and nonvolatile anesthetic drugs such as halothane and thiopental, respectively, cause the same physiological effect. The mechanism(s) underlying anesthesia is not fully understood, although various theories have been proposed. Many of these have centered on the correlation between certain physicochemical properties and anesthetic potency. Thus, the oil/water partition coefficient, the ability to reduce surface tension, and the ability to induce the formation of clathrate compounds with water are all correlated with anesthetic potency. It seems that each of these characteristics are all connected to hydrophobicity, and so the site of action may be a hydrophobic region in a membrane or protein. Thus, again, physicochemical properties determine biological activity. 

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Toxic responses can be divided into six types direct tissue lesions pharmacological, physiological, and biochemical effects teratogenesis immunotoxicity genetic toxicity and carcinogenesis. 

Bibliographic database covering the biochemical, pharmacological, physiological, and toxicological effects of drugs and other chemicals over 2.5 million citations, almost all with abstracts and/ or index terms and CAS registry numbers. 

TOXCENTER TOXCENTER on STN is a bibliographic database that covers the pharmacological, biochemical, physiological, and toxicologicitl effects of drugs and other chemicals. The data m TOXCENTER are from 1907 to the preseni, Tliere are more Ihan 5,7 million records (December, 2002). It is updaled weekly... 

Pharmacodynamics. The processes of the body s responses resulting from treatment with a medicine or compound. The processes include pharmacological, biochemical, physiological, and therapeutic effects. The pharmacodynamics of a response to treatment are presented with the scientific and/or clinical language of the disciplines involved in detecting, measuring, and describing the effects. 

Pharmacodynamics is the study of drug effects (biochemical and physiological) and their mechanism of action. When the drug reaches its site of action it has a pharmacological effect which may be responsible for an eventual therapeutic effect and also responsible for the adverse effects as well as some other effects which may be of no clinical importance. 

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