Toxicity unwanted

Drug biotransformation reactions are essential chemical processes, mainly mediated by enzymes, which lead to the formation of drug metabolites that are excreted from the body. Historically, this metabolism was known as a detoxication mechanism. However, these reactions which govern the pharmacological efficacy of the drugs, may in many cases, also be responsible for toxic unwanted effects. Due to the large variety of chemical structures, drug biotransformation involves numerous and sophisticated... 

Hydrolysis of Nitriles. The chemical hydrolysis of nitriles to acids takes place only under strong acidic or basic conditions and may be accompanied by formation of unwanted and sometimes toxic by-products. Enzymatic hydrolysis of nitriles by nitrile hydratases, nittilases, and amidases is often advantageous since amides or acids can be produced under very mild conditions and in a stereo- or regioselective manner (114,115). 

In 1962, bromacil (5-bromo-3-s-butyl-6-methyluracil 1047 R = Bu ), its homologue (isocil 1047 R = Pr ) and related iV-alkyluracils were shown to have valuable selective phytotoxic properties and vitually no mammalian toxicity. Thus, bromacil achieves a complete kill of most unwanted broad-leaf annuals or perennials along with some grasses... 

Bioremediation- Use of microorganisms to remove or detoxify toxic or unwanted chemicals from an environment. 

The characteristics of the downstream pollution discharge must be monitored (see Fig. 13.18). It is essential that the operation and maintenance of the pollution control equipment be included in a quality audit procedure, assisting in determining the operation efficiency of the equipment and the formation of unwanted and possibly toxic compounds in the pollution control steps. Unsuitable operation of an incinerator may result in partial oxidation and formation of unwanted combustion products or excessive formation of MO. 

GTP is a safe operation. A runaway polymerization can be quickly quenched with a protonic solvent. Since the group transfer polymerization goes to completion, no unwanted toxic monomer remains the silicone group on the living end after hydroxylation is removed as inactive siloxane. The living polymer in GTP is costlier than traditional polymerization techniques because of the stringent reaction conditions and requirements for pure and dry monomers and solvents. It can be used in fabrication of silicon chips, coating of optical fibers, etc. 

A further way in which metabolic control may be exercised is the artificial deprivation of required ions and cofactors, for example aconitase must have ferrous ions for activity. Conversely, addition of toxic ions is possible, for example aconitase is inhibited by cupric ions. Finally the use of metabolic analogues is possible. If monofluoroacetate is added to cells then monofluorocitrate is produced by titrate synthase and this compound inhibits the activity of aconitase. Great care has to be taken when using metabolic analogues, however, they are often less than 100% specific and may have unexpected and unwanted serious side effects. 

All drugs, in addition to their therapeutic effects, have the potential to do harm, i.e. to cause adverse/unwanted reactions (side effects). These may or may not be related to the principal pharmacological action of the drug. Examples of the second category are toxic effects of metabolites of a drug or immunological reactions. 

The requirements of protease inhibitors as drugs in terms of potency, pharmacokinetics, and toxicity will vary depending on the nature of the infection and the goals of therapy. At one extreme is treatment of HlV-1, a chroific infection that requires life-long therapy and full suppression of viral replication. At the other extreme is the treatment of human rhinovirus (i.e., the cold virus), where short-term treatment to blunt viremia will likely be sufficient to reduce the unwanted symptoms of a cold. In all cases, viral proteases represent very attractive targets with familiar mechanisms of catalysis that frequently allow for the design of transition state analogs and with distinct specificities from host proteases. 

Risk analysis. The risk of accidents can be assessed in terms of two factors severity and probability of the accident. Severity is high if consequences of the accident to employees, the public, the environment, and the plant are significant. Severity is related to the amount and properties of hazardous (toxic, flammable, explosive) substances that can escape to the surroundings during the accident, and to the energy that is released during the accident. Probability is associated with the likelihood of the occurrence of unwanted chains of events and the time of development of undesired events starting from the disturbance. If the time... 

Chemical interaction together with heat of the side reaction expresses the potential reactiveness present in the process. The unwanted side reactions may be e.g. rapid polymerization, heat formation, and formation of flammable or toxic gas. Side reactions and possible reaction risks in the storage systems etc. are taken into account by the heat of reaction and chemical interaction. 

In a process, chemical interaction is either intended or unintended. The wanted reactions are under control, e.g. in the reactor. Unwanted chemical interaction can lead to unpleasant surprises like heat formation, fire, formation of harmless and nonflammable gas, formation of toxic gas, formation of flammable gas, explosion, rapid polymerization, or soluble toxic chemicals. 

Electrolysis is an environmentally friendly technology. Properly designed electrochemical processes which use a mass-free reagent (the electron without the need of additional chemicals at ambient temperature) do not produce unwanted effluents, they often do not need toxic compounds (such as CN ) and do not introduce hazards of their own. 

Safety Pharmacology. It is important to investigate the potential for unwanted pharmacological activity in appropriate animal models and to incorporate monitoring for these activities in the toxicity studies. 

Adverse event. Unwanted effects that occur and are detected in populations. The term is used whether there is or is not any attribution to a medicine or other cause. Adverse events may be known parts of a disease that are observed to occur within a period of observation, and they may be analyzed to test for their frequency in a given population or trial. This is done to determine if there is an unexpectedly increased frequency resulting from nondisease factors such as medicine treatment. The term adverse event or adverse experience is used to encompass adverse reactions plus any injury, toxicity, or hypersensitivity that may be medicine-related, as well as any medical events that are apparently unrelated to medicine that occur during the study (e.g., surgery, illness, and trauma). See definition of Adverse reaction. 

Scheme 9.1 shows a generalized sequence of reactions for the oxidation of an alkane, via alcohol, ketone and carboxylic acid, to the completely oxidized products, water and carbon dioxide. The latter are often referred to as combustion products as they are the same as those formed by burning hydrocarbons. These are not normally desirable chemical products unless it is necessary to destroy a toxic, hazardous or otherwise unwanted waste material. Oxidation itself is not difficult to achieve, and is a highly exothermic or even explosive process. Selective oxidation, however, is a much greater challenge, as it is important to stop the sequence at the desired product without proceeding further down the oxidation pathway. 

Yet hands-on experience with 1 and other related compounds showed that free malonic acid groups on fullerenes are rather unstable even under physiological conditions and readily decarboxylate into side products, some of which may show toxicity under certain circumstances (Beuerle et al., 2007). To avoid these potential side effects new polar derivatives of 1 like 3, 4 and 5 have been synthesized (Beuerle et al., 2005 Witte et al., 2007). In these trisadducts the polar endgroups are attached via alkyl spacers to the fullerene core and thus no unwanted decarboxylation... 

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