Drug compound chemical activity

The mutual chemistry of plastic containers and food products must be considered for any proposed application. There is continuous physical and chemical activity at the interface between the food product and the container. The type and extent of this activity determines whether or not the plastic container can successfully hold and protect the food product. However, the U.S. Food and Drug Administration and the American public are increasingly suspicious of all plastics, particularly the halo-genated compounds. The recent ban (April 1973) on poly(vinyl chloride)... 

MAO-inhibitors are chemical compounds whose activity in the body slows down or interferes with Mono Amine Oxidase, an enzyme system that oxidizes many compounds in foods and drugs into harmless byproducts. In the presence of MAO-inhibitors, compounds that would normally be metabolized into inactive by-products instead have the duration of their physiological and psychological activity extended. 

If an interesting activity is described, larger quantities (10-100 kg) of the plant material are collected, from which chemists purify and characterize the active principle. The active principle is known as a lead compound . Chemists will then usually attempt to modify the lead compound in order to render it more therapeutically useful (e.g. make it more potent, or perhaps increase its hydrophobicity so that it can pass through biological membranes). This is then subjected to further pre-clinical trials, and chemists determine whether an economically feasible method, allowing the drug s chemical synthesis, can be developed. 

Both metabolism and excretion can be viewed as processes responsible for elimination of drug (parent and metabolite) from the body. Drug metabolism changes the chemical structure of a drug to produce a drug metabolite, which is frequently but not universally less pharmacologically active. Metabolism also renders the drug compound more water soluble and therefore more easily excreted. 

Cutaneous biotransformation is mostly associated with the stratum basale layer where there can be phase I and phase II metabolism. However, the skin is not very efficient, compared to the liver. The epidermal layer accounts for the major portion of biochemical transformations in skin, although the total skin activity is low (2-6% that of the liver). Where activity is based on epidermis alone, that layer is as active as the liver or, in the case of certain toxicants, several times more active. For some chemicals, metabolism can influence absorption, and transdermal delivery systems of drugs utilize this activity. For example prodrug such as lipid esters are applied topically, and cutaneous esterases liberate the free drug. These basal cells and extracellular esterases have been shown to be involved in detoxification of several pesticides and bioactivation of carcinogens such as benzo(a)pyrene. For rapidly penetrating substances, metabolism by the skin is not presently considered to be of major significance, but skin may have an important first-pass metabolic function, especially for compounds that are absorbed slowly. 

Pro-drugs are systems comprising drug molecules chemically bonded to a polymer carrier. The drug converts to the active compound at a specific tissue site, often through the agency of an enzyme or receptor [53-56]. 

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