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Medicinal Chemistry is the science that deals with the discovery or design of new therapeutic chemicals and their development into useful medicines. It may involve synthesis of new compounds, investigations of their relationships between the structure of natural or synthetic compounds and their biological activities, elucidations of their interactions with receptors of various kinds, including enzymes and DNA, the determination of their absorption, transport, and distribution properties, and studies of the metabolic transformations of these chemicals into other chemicals.
Medicinal chemistry, in its crudest sense, has been practiced for several thousand years. Man has searched for cures of illnesses by chewing herbs, berries roots, and barks. Some of these early clinical trials were quite successful, however, not until the last 100 year has knowledge of the active constituents of these natural sources been known. The earliest written records of the Chinese, Indian, South American, and Mediterranean cultures described the therapeutic effects of various plant concoctions. If the approach to drug discovery continued as in ancient times, few diseases would be treatable today. Natural products make up a small percentage of drugs on the current market. Typically, when a natural product is found to be active, it is chemically modified in order to improve its properties. As a result of advances made in synthesis and separation methods and biochemical techniques since the late 1940s, a more rational approach to drug discovery has been possible, namely, one which involves the element of design.
- Adrenergic Drugs
- The compounds ordinarily classified as central stimulants are drugs that increase behavioral activity, thought processes, and alertness or elevate the mood of an individual. These drugs differ widely in their molecular structures and in their mechanism of action. Thus, describing a drug as a stimulant does not adequately describe its medicinal chemistry. The convulsions induced by a stimulant such as strychnine, for example, are very different from agitation induced by amphetamine.
- Analgesics and Anti-Inflammatory Agents
- The anti-inflammatory, analgesic, and antipyretic drugs are a heterogeneous group of compounds, often chemically unrelated (although most of them are organic acids), which nevertheless share certain therapeutic actions and side effects. The prototype is aspirin; hence these compounds are often referred to as aspirin-like drugs. All aspirin-like drugs are antipyretic, analgesic, and anti-inflammatory, but there are important differences in their activities.
- Anticancer Drugs
- When fighting cancer, the entire population of neoplastic cells must be eradicated in order to obtain desired results. The logical outgrowth of these concepts has been the attempt to achieve total cell-kill by the use of several chemotherapeutic agents concurrently or in rational sequences. The resulting prolonged survival of patients with acute lymphocytic leukemia through the use of such multiple-drug regimens has encouraged the application of these principles the treatment of other neoplasms.
- Antihistamines and Local Anesthetics
- Histamine is 2-(4-imidazolyl)ethylamine and is a hydrophilic molecule comprised of an imadazole ring and an amino group connected by two methylene groups. It arises in vivo by decarboxylation of the amino acid histadine. Histamine is a neurotransmitter in the CNS and a typical problem with some antihistamines is drowsiness. The effort has been to produce compounds that do not enter the brain very well.
- Antimicrobial Drugs
- An antibiotic is any substance produced by a microorganism that is excreted to harm or kill another microorganism. Technically, antibiotics are microbial or fungal products. But these substances can be synthesized and mass produced in the laboratory to use against harmful microorganisms in the environment. Antibiotics can further be grouped under the broader heading of chemotherapuetic agents, chemical agents used to treat disease. Good chemotherapuetic agents are able to kill or inhibit the tar
- Basic Aspects of Drug Activity
- While there are several types of exeptions, the effects of most drugs result from their interaction with functional macromolecular components of the organism. Such interaction alters the function of the pertinent cellular component and thereby initiates the series of biochemical and physiological changes that are characteristic of the response to the drug. The term receptor is used to denote the component of the organism with which the chemical agent interacts.
- Cardiovascular Drugs
- Cardiovascular disease constitutes the largest single cause of death in the industrialized countries. As with cancer, which is a distant second in terms of mortality, cardiovascular disease morbidity increases with age, accounting for about two-thirds of all deaths in persons over 75. Even though some diseases affect primarily the heart and other diseases effect the vascular system, they cannot be divorced from each other. This obvious interdependence makes a unified imperative.
- Cholinergic Drugs I - Nicotinic and Muscarinic Receptors
- A cholinergic drug is any of various drugs that inhibit, enhance, or mimic the action of the neurotransmitter acetylcholine within the body. Acetylcholine stimulation of the parasympathetic nervous system helps contract smooth muscles, dilate blood vessels, increase secretions, and slow the heart rate. Some cholinergic drugs, such as muscarine, pilocarpine, and arecoline, mimic the activity of acetylcholine in stimulating the parasympathetic nervous system. These drugs have few therapeutic uses.
- Colinergic Drugs II - Anticholinesterase Agents & Acetylcholine Antagonists
- Acetylcholine is inactivated by the enzyme acetylcholinesterase (enlarged), which is located at cholinergic synapses and breaks down the acetylcholine molecule into choline and acetate. Three particularly well-known drugs, neostigmine, physostigmine, and diisopropyl fluorophosphate, inactivate acetylcholinesterase so that it cannot hydrolyze the acetylcholine released at the nerve ending. As a result, acetylcholine increases in quantity with successive nerve impulses.
- In most instances of natural neuron inhibition GABA is the inhibitory transmitter. GABA has the specific effect of opening anion channels in nerves, allowing large numbers of chloride ions to diffuse into the terminal fibril.
- Psychoactive Drugs
- A sedative drug decreases activity, moderates excitement, and calms the recipient. A hypnotic drug produces drowsiness and facilitates the onset and maintenance of a state of sleep that resembles natural sleep in its electrocephalographic characteristics and from which the recipient may be easily aroused; the effect is sometimes called hypnosis.