Everything about Pharmacological totally explained
Pharmacology is the study of how
drugs interact with living organisms to produce a change in function. If substances have
medicinal properties, they're considered
pharmaceuticals. The field encompasses
drug composition and properties,
interactions,
toxicology, therapy, and medical applications and antipathogenic capabilities. Pharmacology isn't synonymous with
pharmacy, which is the name used for a profession. Though in common usage the two terms are confused at times. Pharmacology deals with how drugs interact within biological systems to affect function, while pharmacy is a medical science concerned with the safe and effective use of medicines.
The origins of
clinical pharmacology date back to the
Middle Ages in
Avicenna's
The Canon of Medicine,
Peter of Spain's
Commentary on Isaac, and John of St Amand's
Commentary on the Antedotary of Nicholas. Pharmacology as a scientific discipline didn't further advance until the mid-19th century amid the great biomedical resurgence of that period. Before the second half of the nineteenth century, the remarkable potency and specificity of the actions of drugs such as
morphine,
quinine and
digitalis were explained vaguely and with reference to extraordinary chemical powers and affinities to certain organs or tissues. The first pharmacology department was set up by
Buchheim in 1847, in recognition of the need to understand how therapeutic drugs and poisons produced their effects.
Divisions
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 study of the effects of poisons
- theoretical pharmacology
- posology - how medicines are dosed
- pharmacognosy - deriving medicines from plants
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 signaling or
metabolic pathways by affecting sites directly on cell-surface receptors (which modulate and mediate cellular signaling 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 (for example
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 tumors.
Medicine development and safety testing
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.
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.
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 and selling.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's 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 Medicines and Healthcare products Regulatory Agency (MHRA) has a similar role in the UK.
Education
The study of pharmacology is offered in many universities worldwide.
Again, pharmacology education programs differ from pharmacy programs. Students of pharmacology are trained as researchers, studying the effects of substances in order to better understand the mechanisms which might lead to new drug discoveries for example. Whereas as pharmacy student will eventually work in a pharmacy dispensing medications or some other position focused on the patient, pharmacologist will typically work within a laboratory setting.
Some higher educational institutions combine pharmacology and toxicology into a single program as does
Michigan State University. Michigan State University offers PhD training in Pharmacology & Toxicology with an optional Environmental Toxicology specialization. They also offer a Professional Science Masters in Integrative Pharmacology.
Further Information
Get more info on 'Pharmacological'.
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