PHARMACOLOGY

'Pharmacology' (in Greek: ''pharmakon (φάρμακον)'' meaning drug, and ''lego (λέγω)'' to tell (about)) is the study of how drugs interact with living organisms to produce a change in function. Pharmacology: An Introduction, , Hinter, Nagle, McGraw Hill, 2005, ISBN 0-07-312275-0 If substances have medicinal properties, they are considered 'pharmaceuticals'. The field encompasses drug composition and properties, interactions, toxicology, therapy, and medical applications and antipathogenic capabilities.
Development of medication is a vital concern to medicine, but also has strong economical and political implications. To protect the consumer and prevent abuse, many governments regulate the manufacture, sale, and administration of medication. In the United States, the main body that regulates pharmaceuticals is the Food and Drug Administration and they enforce standards set by the United States Pharmacopoeia. In the European Union, the main body that regulates pharmaceuticals is the EMEA and they enforce standards set by the European Pharmacopoeia.
Pharmacology as a chemical science is practiced by pharmacologists. Subdisciplines include ''clinical pharmacology'' (the medical field of medication effects on humans), ''neuro-'' and ''psychopharmacology'' (effects of medication on behavior and nervous system functioning), ''pharmacogenetics'' (clinical testing of genetic variation that gives rise to differing response to drugs), ''pharmacogenomics'' (application of genomic technologies to new drug discovery and further characterization of older drugs), ''pharmacoepidemiology'' (study of effects of drugs in large numbers of people), ''toxicology'' and ''theoretical pharmacology''.
Pharmacology is not identical with pharmacy, though in common usage the two are at times confused. Pharmacology deals with how drugs interact within biological systems to effect function. Pharmacy is a medical science which is concerned with the safe use of medication.

Medicine development and safety testing

If the structure of a medicine is altered slightly, this will slightly alter the medicine's properties. This means when a useful activity has been identified, chemists will make many similar compounds called analogues, to attempt and maximise the beneficial effects. This development phase can take up to 3 years and is expensive.^[1]
These new analogues need to be developed. It needs to be determined how safe the medicine is for human consumption, its stability in the human body and the best form for dispensing, like tablet or aerosol. After extensive testing, which can take up to 6 years the new medicine is ready for marketing.
As a result of the long time required to develop analogues and test a new medicine and the fact that of every 5000 potential new medicines typically only one will ever reach the open market, this is an expensive way of doing things, costing millions of dollars. To recoup this outlay pharmaceutical companies may do a number of things:

★ Carefully research the demand for their potential new product before spending an outlay of company funds.

★ Obtain a patent on the new medicine preventing other companies from producing that medicine for a certain allocation of time.

Drug legislation and safety

In the United States, the Food and Drug Administration (FDA) is responsible for creating guidelines for the approval and use of drugs. The FDA requires that all approved drugs fulfill two requirements:
# The drug must be found to be effective against the disease for which it is seeking approval.
# The drug must meet safety criteria by being subject to extensive animal and controlled human testing.
Gaining FDA approval usually takes several years to attain. Testing done on animals must be extensive and must include several species to help in the evaluation of both the effectiveness and toxicity of the drug. The dosage of any drug approved for use is intended to fall within a range in which the drug produces a therapeutic effect or desired outcome.
The safety and effectiveness of prescription drugs in the U.S. is regulated by the federal Prescription Drug Marketing Act of 1987.
The Medicines and Healthcare products Regulatory Agency (MHRA) has a similar role in the UK.

Scientific background

The study of chemicals requires intimate knowledge of the biological system affected. With the knowledge of cell biology and biochemistry increasing, the field of pharmacology has also changed substantially. It has become possible, through molecular analysis of receptors, to design chemicals that act on specific cellular signalling or metabolic pathways by affecting sites directly on cell-surface receptors (which modulate and mediate cellular signalling pathways controlling cellular function).
A chemical has, from the pharmacological point-of-view, various properties. Pharmacokinetics describes the effect of the body on the chemical (e.g. half-life and volume of distribution), and pharmacodynamics describes the chemical's effect on the body (desired or toxic).
When describing the pharmacokinetic properties of a chemical, pharmacologists are often interested in ''ADME'':

★ Absorption - How is the medication absorbed (through the skin, the intestine, the oral mucosa)?

★ Distribution - How does it spread through the organism?

★ Metabolism - Is the medication converted chemically inside the body, and into which substances. Are these active? Could they be toxic?

★ Excretion - How is the medication eliminated (through the bile, urine, breath, skin)?
Medication is said to have a narrow or wide ''therapeutic index'' or ''therapeutic window''. This describes the ratio of desired effect to toxic effect. A compound with a narrow therapeutic index (close to one) exerts its desired effect at a dose close to its toxic dose. A compound with a wide therapeutic index (greater than five) exerts its desired effect at a dose substantially below its toxic dose. Those with a narrow margin are more difficult to dose and administer, and may require therapeutic drug monitoring (examples are warfarin, some antiepileptics, aminoglycoside antibiotics). Most anti-cancer drugs have a narrow therapeutic margin: toxic side-effects are almost always encountered at doses used to kill tumours.

Drugs used as medicines

Main articles: Medication

A 'medication' is a licensed drug (chemical) taken to cure, prevent or reduce symptoms of an illness or medical condition.
Medications are generally divided into two groups -- ''over-the-counter'' (OTC) medications, which are available without special restrictions, and ''Prescription only medicines'' (POM), which must be prescribed by a physician. Most OTC medication is generally considered to be safe enough that most persons will not hurt themselves accidentally by taking it as instructed. Many countries, such as the UK have a third category of pharmacy medicines which can only be sold in registered pharmacies, by or under the supervision of a pharmacist.
However, the precise distinction between OTC and prescription depends on the legal jurisdiction.
Medications are typically produced by pharmaceutical companies and are often patented. Those that are not patented are called generic drugs.

Education

Footnotes

1. Revise A2 Chemistry, , David, Newton, Heinemann Educational Publishers, ,

External links

★ Pharmaceutical Business Review.

★ Pharmaceutical company profiles at NNDB.

★ International Conference on Harmonisation.

★ US Pharmacopeia.

★ Medicine updates.

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