The medical and nursing professions use the words "drugs" to refer to
medicines - substances that can cure or arrest disease, relieve symptoms,
ease pain, and provide other benefits this definition includes essential
vitamins and minerals that may be given to correct deficiency diseases.
Powerful drugs often have marked side effects. Commonly used drugs with less
potential to cause harm are sold over the counter in pharmacies and
supermarkets. More powerful drugs (those that the Medicines Commission has
ruled cannot be used safely without medical supervision) require a doctor's
prescription
A different use of the word "drugs" refers to those substances on which a
person may become dependent. These range from mild stimulants such as
caffeine (found in tea and coffee) to powerful agents that alter mood and
behaviour some addictive drugs have no medical use and cannot be obtained
legally.
Where drugs come from..
At one time, the only available drugs were substances extracted from plants,
or, in some cases, animals Herbalism, the study and medicinal use of plants,
was practised by the Chinese more than 5,000 years ago and thrives in many
parts of the world today.
Virtually all the drugs in current use have been developed in the laboratory
and are manufactured through various chemical processes . About a quarter of
these are derived from plants or other organisms. Most drugs are synthetic
chemical copies, but some are still extracted from natural sources for
example, the opioid drugs, including morphine, are made from a species of
poppy. Many antibiotics and some anticancer drugs are still of natural origin.
The main difference between drugs of plant origin and "herbal medicines" is that the drugs have been thoroughly
tested for safety and to prove that they work.
Some drugs can now be made through genetic engineering, in which the genes (which
control a cell's function) of certain microorganisms are altered, changing
the products of cell activity to the desired drug For example, the hormone
insulin can now be manufactured by genetically engineered bacteria .This
could eliminate the need to extract insulin from animal pancreas glands, the
source until recently, benefiting those people who experience adverse
reactions to material derived from animal sources.
Purely synthetic drugs are either modifications of naturally occurring ones,
with the aim of increasing effectiveness or safety, or drugs developed after
scientific investigation of a disease process with the intention of changing
it biochemically
Developing and marketing new drags
Pharmaceutical manufacturers find new products in a variety of ways new
drugs are usually developed for one purpose but quite commonly a variant
will be found that will be useful for something entirely different.
When a new drug is discovered, the manufacturer often undertakes a programme
of molecular tinkering, or elaboration. This refers to investigations into
variants of the drug to see if the substance can be made more effective or
more free of adverse effects. In some cases that experimental process has
unexpected results The elaboration process, for example, transformed some
sulpha drugs, which were originally valued for their antibacterial
properties, into widely used oral antidiabetics, diuretics, and
anticonvulsants.
All new drugs undergo a long, careful test period before they are approved
for marketing by the Committee on Safety of Medicines (CSM) . Once approval has been given, the manufacturer can then
market the drug under a brand or trade name Technically, the manufacturer
has exclusive rights to the drug for 20 years, although in actual fact the
period of the manufacturer's patent protection is often far shorter.
When patent protection ends, other manufacturers may produce the drug,
although they must use a different brand name.
Testing and approving new drugs
Before a drug is cleared by the CSM it undergoes a cautious step by-step
period of testing often lasting six to ten years By law a drug must be both
safe and medically effective Safety is established through various means,
including tests on animals and human volunteers Efficacy is proven through
complex tests (including double-blind trials) on groups of healthy and ill
patients The testing is done in various research institutions under
government-approved procedures
The approval process also involves weighing a new drug's risks against its
benefits a dangerous drug whose only potential might be the relief of an
ordinary headache undoubtedly would not win approval yet an equally Toxic
drug effective against cancer might Medical judgment is an important part of
the approval process.
Developing and testing new drugs
All new drugs undergo a rigorous testing period in the laboratory.
The 5,000 or so substances loosely called drugs are described in
many ways. Scientists and pharmacologists, interested in chemical structure, use
one system. Doctors, concerned with use, employ another. Manufacturers and
advertisers, promoting the benefits of their products, use simpler, more
appealing names. Government regulators, wary of the harm some drugs may do,
classify them in a different manner altogether, according to their legal status.
Specific names
All drugs in general use rely on three terms the generic, brand, and chemical
names The generic name, which is the official medical name for the basic active
substance.
The brand name is chosen by the manufacturer, usually on the basis that it can
be easily pronounced, recognized, or remembered. There may be several brands (each
by a different manufacturer) containing the same generic substance Differences
between the brands may be slight but may relate to absorption rate (bioavailability),
convenience, and digestibility A drug may be available in generic form, as a
brand-name product, or both Some brand-name products contain several generic
drugs. The chemical name is a technical description of the drug, and is not
used.
For example, the three names for a drug used to help those with AIDS are as
follows The generic name is zidovudine, the brand name is Retrovir (generic
names are not capitalized, brand names are), and the chemical name is
3-azldo-3-deoxythymidine.
General terms
Drugs may be grouped according to chemical similarity, for example, the
benzodiazepines. More often, though, drugs are classified according to use (antihypertensive)
or biological effect (diuretic). Most drugs fit into one group, although many
have multiple uses and are listed in several categories
We have grouped drugs according to use, although a chemical description may be
added to distinguish one group of drugs from others used to treat the same
disorder (for example, benzodiazepine sleeping drugs)
Legal classification
Besides specifying which drugs can be sold over the counter and which require a
doctor's prescription, government regulations determine the degree of
availability of many substances that have an abuse potential .Regulated drugs
are also classified by how harmful they are when abused.
The Misuse of Drugs Regulations define those people who are authorized in
their professional capacity to supply and possess controlled drugs .The
Regulations also describe the requirements for legally undertaking these
activities such as storage of the drugs and limits on their prescription Drugs
are divided into five schedules based on their potential for abuse if misused.
Schedule I
Virtually all the drugs in this group are prohibited except in
accordance with Home Office authority all of them have a high potential for
abuse and are not used medicinally.
Examples - Marijuana (cannabis) LSD
Schedule II
Like Schedule I drugs, these have a high potential for abuse
and can lead to physical and psychological dependence. They have an accepted
medical use, but are subject to full controlled drug requirements Most of them
are stimulants, opioids or depressants Prescriptions cannot be renewed.
Examples - Amphetamines cocaine diamorphine (heroin), glutethimide
morphine pethidine, quinalbarbitone
Schedule III
Drugs in this group have a lower potential for abuse than those
in Schedules I and II but they are nevertheless subject to special prescription
requirements Prescriptions for Schedule III drugs may be repeated if authorized.
Examples - Barbiturates, diethylpropion, mazindol, meprobamate,
methyprylone pentazocine, phentermine, temazepam.
Schedule IV
The drugs in this group have a lower potential for abuse than
Schedule I-III drugs and are subject to minimal control .Special prescription
requirements do not apply.
Examples - Benzodiazepines
Schedule V
These drugs have a low potential for abuse because of their low
strength .For the most part, they are preparations that contain small amounts of
opioid drugs, but are exempt from controlled drug requirements.
Examples - Kaolin and morphine (an antidiarrhoeal), codeine linctus (a cough
suppressant) DF118 tablets (an opioid analgesic containing dihydrocodeine)
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