CD-ROM Today (UK) (Spanish) 15/CDRT.iso/dp/0299/02991.txt

Text File | 1994-01-17 | 17KB | 309 lines

$Unique_ID{BRK02991}
$Pretitle{}
$Title{The New Prescription Drug Reference Guide - How Drugs Work, part II}
$Subject{Types CARDIOVASCULAR Antianginals Antiarrhythmics Antihypertensives
Diuretics Cardiac Glycosides Anticoagulants Antihyperlipidemics Vasodilators
Beta Blockers Calcium Channel Blockers EARS EYES GASTROINTESTINAL
Antinauseants Anticholinergics Antiulcer Antidiarrheals HORMONES Thyroid
Antidiabetic Steroids Sex Hormones ANTI-INFECTIVES Antibiotics Antivirals
Vaccines anthelmintics pediculicide scabicide ANTINEOPLASTICS TOPICAL CENTRAL
NERVOUS SYSTEM Sedatives Tranquilizers Antidepressants Amphetamines
Anticonvulsants Antiparkinsonism Agents Analgesics Anti-Respiratory
Antitussives Expectorants Decongestants Bronchodilators Antihistamines
VITAMINS MINERALS}
$Volume{}
$Log{}

Copyright (C) 1993 Publications International, Ltd.


How Drugs Work, part II
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     Sex Hormones

     Although the adrenal glands secrete small amounts of sex hormones, these
hormones are produced mainly by the sex glands.  Estrogens are the female
hormones responsible for secondary sex characteristics such as development of
the breasts and maintenance of the lining of the uterus.  Testosterone
(androgen) is the corresponding male hormone.  It is responsible for secondary
sex characteristics such as a beard, a deepened voice, and the maturation of
external genitalia.  Progesterone is also produced in females--it prepares the
uterus for pregnancy.
     Testosterone reduces elimination of protein from the body, thereby
producing an increase in muscle size.  Athletes sometimes take drugs called
anabolic steroids (chemicals similar to testosterone) for this effect, but
such use of these drugs is dangerous.  Anabolic steroids can adversely affect
the heart, nervous system, and kidneys.
     Most oral contraceptives (birth control pills) combine estrogen and
progesterone, but some contain only progesterone.  The estrogen in birth
control pills prevents egg production.  Progesterone aids in preventing
ovulation, alters the lining of the uterus, and thickens cervical
mucus--processes that help to prevent conception and implantation.  Oral
contraceptives have many side effects, so their use should be discussed with a
physician.
     Conjugated estrogens are used as replacement therapy to treat symptoms of
menopause in women whose bodies are no longer producing sufficient amounts of
estrogen.  Medroxyprogesterone is used to treat uterine bleeding and menstrual
problems.  It prevents uterine bleeding by inducing and maintaining a lining
in the uterus that resembles the lining produced during pregnancy.  In
addition, it suppresses the release of the pituitary gland hormone that
initiates ovulation.

ANTI-INFECTIVES

     Antibiotics

     Antibiotics are used to treat a wide variety of bacterial infections.
They are usually derived from molds or are produced synthetically.
Antibiotics inhibit the growth of bacteria by interfering with their
production of certain biochemicals necessary to sustain life or by interfering
with their ability to use nutrients.  The body's defenses then have a much
easier time eliminating the infection.
     When used properly, antibiotics are usually effective.  To adequately
treat an infection, antibiotics must be taken regularly for a specific period
of time.  If you do not take an antibiotic for the prescribed period,
microorganisms resistant to the antibiotic are given the opportunity to
continue growing, and your infection could recur.  Aminoglycosides,
cephalosporins, erythromycins, penicillins (including ampicillin and
amoxicillin), and tetracyclines are some examples of antibiotics.
     Antibiotics do not counteract viruses, such as those causing the common
cold, so their use in cold therapy is inappropriate.

     Antivirals

     Antiviral drugs are used to combat viral infections.  An antiviral drug
called acyclovir is being used in the management of herpes.  Acyclovir reduces
the reproduction of the herpes virus in initial outbreaks, lessens the number
of recurring outbreaks, and speeds the healing of herpes blisters.  However,
this antiviral drug does not cure herpes.

     Vaccines

     Vaccines were used long before antibiotics became available.  A vaccine
contains weakened or dead disease-causing microorganisms or parts of such
organisms, which activate the body's immune system to produce a natural
defense against a particular disease (such as polio or measles).  A vaccine
may be used to alleviate or treat an infectious disease, but most commonly it
is used to prevent a specific disease.

     Other Anti-infectives

     Drugs called anthelmintics are used to treat worm infestations.  Fungal
infections are treated with antifungals (such as nystatin)--drugs that destroy
and prevent the growth of fungi.
     A pediculicide is a drug used to treat a person infested with lice, and a
scabicide is a preparation used to treat a person with scabies.

ANTINEOPLASTICS

     Antineoplastic drugs are used in the treatment of cancer.  Most of the
drugs in this category prevent the growth of rapidly dividing cells, such as
cancer cells.  Antineoplastics are, without exception, extremely toxic and can
cause serious side effects.  But for many cancer victims, the benefits derived
from chemotherapy with antineoplastic drugs far outweigh the risks involved.

TOPICAL DRUGS

     Drugs are often applied topically (locally to the skin) to treat skin
disorders with minimal systemic (throughout the body) side effects.
Antibiotic creams or ointments are used to treat skin infections, and
adrenocorticosteroids are used to treat inflammatory skin conditions.  Another
common dermatologic (skin) problem is acne.  Acne can be--and often
is--treated with over-the-counter drugs, but it sometimes requires
prescription medication.  Antibiotics such as tetracycline, erythromycin, or
clindamycin are used orally or applied topically to slow the growth of the
bacteria that play a role in the formation of acne pustules.  Keratolytics
(agents that soften the skin and cause the outer cells to slough off) are also
sometimes prescribed.
     Some drugs applied to the skin do have effects within the body.  For
example, nitroglycerin is absorbed into the bloodstream from ointment or
patches placed on the skin.  The absorbed nitroglycerin dilates blood vessels
and prevents anginal pain.  Clonidine, scopolamine, and estrogen are available
as transdermal patches, also.

CENTRAL NERVOUS SYSTEM DRUGS

     Sedatives

     Medications used in the treatment of anxiety or insomnia selectively
reduce activity in the central nervous system (brain and spinal cord).  Drugs
that have a calming effect include barbiturates, chlordiazepoxide,
clorazepate, diazepam, doxepin, hydroxyzine, meprobamate, and oxazepam.  Drugs
to induce sleep in insomniacs include butabarbital, flurazepam, temazepam, and
triazolam.

     Tranquilizers

     Major tranquilizers or antipsychotic agents are usually prescribed for
patients with psychoses (certain types of mental disorders).  These drugs calm
certain areas of the brain but permit the rest of the brain to function
normally.  They act as a screen that allows transmission of some nerve
impulses but restricts others.  The drugs most frequently used are
phenothiazines, such as chlorpromazine and thioridazine.  Haloperidol, a
butyrophenone, has the same effect as chlorpromazine.

     Antidepressants

     Tricyclic antidepressants (such as amitriptyline), tetracyclic
antidepressants (such as maprotiline), and monoamine oxidase (MAO) inhibitors
(such as phenelzine) are used to combat depression.  Antidepressants are also
used in the preventive treatment of migraine headaches, although the manner in
which they help these headaches is not clearly understood.
     Antidepressants may produce serious side effects, and they can interact
with other drugs.  MAO inhibitors can also interact with certain foods,
resulting in dangerous increases in blood pressure.  Therefore, they should be
used very carefully.

     Amphetamines

     Amphetamines or adrenergic drugs are commonly used as anorectics (drugs
used to reduce the appetite).  These drugs temporarily quiet the part of the
brain that causes hunger, but they also keep a person awake, speed up the
heart, and raise blood pressure.  After two to three weeks, these medications
begin to lose their effectiveness as appetite suppressants.
     Amphetamines stimulate most people, but they have the opposite effect on
hyperkinetic children.  Hyperkinesis (the condition of being highly
overactive) is difficult to diagnose or define and requires a specialist to
treat.  When hyperkinetic children take amphetamines or the adrenergic drug
methylphenidate, their activity slows down.  Most likely, amphetamines quiet
these youngsters by selectively stimulating parts of the brain that ordinarily
provide control of activity.

     Anticonvulsants

     Drugs such as phenytoin and phenobarbital are used to control seizures
and other symptoms of epilepsy.  They selectively reduce excessive stimulation
in the brain.

     Antiparkinsonism Agents

     Parkinson's disease is a progressive disorder that is due to a chemical
imbalance in the brain.  Victims of Parkinson's disease have uncontrollable
tremors, develop a characteristic stoop, and eventually become unable to walk.
Drugs such as benztropine, trihexyphenidyl, levodopa, and bromocriptine are
used to correct the chemical imbalance, thereby relieving the symptoms of the
disease.  Benztropine and trihexyphenidyl are also used to relieve tremors
caused by other medications.

     Analgesics

     Pain is not a disease but a symptom.  Drugs used to relieve pain are
called analgesics.  These drugs form a rather diverse group.  We do not fully
understand how most analgesics work.  Whether they all act on the brain is not
known.  Analgesics fall into two categories; they may be either narcotic or
nonnarcotic.
     Narcotics are derived from the opium poppy.  They act on the brain to
cause deep analgesia and often drowsiness.  Some narcotics relieve coughing
spasms and are used in many cough syrups.  Narcotics relieve pain and give the
patient a feeling of well-being.  They are also addictive.  Manufacturers have
attempted to produce nonaddictive synthetic narcotic derivatives but have not
yet been successful.
     Many nonnarcotic pain relievers are commonly used.  Salicylates are the
most commonly used pain relievers in the United States today.  The most widely
used salicylate is aspirin.  While aspirin ordinarily does not require a
prescription, many doctors may prescribe it to treat such diseases as
arthritis.
     The aspirin substitute acetaminophen may be used in place of aspirin to
relieve pain.  It does not, however, reduce inflammation (such as that caused
by arthritis).
     A number of analgesics contain codeine or other narcotics combined with
nonnarcotic analgesics (such as aspirin or acetaminophen).  These analgesics
are not as potent as pure narcotics but are frequently as effective.  Because
these medications contain narcotics, they have potential for abuse and must be
used with caution.

     Anti-inflammatory Drugs

     Inflammation is the body's response to injury.  It causes swelling, pain,
fever, redness, and itching.  Aspirin is one of the most effective
anti-inflammatory drugs.  Other drugs, called nonsteroidal anti-inflammatory
drugs (for example, fenoprofen, ibuprofen, indomethacin, naproxen, and
tolmetin), relieve inflammation and may be more effective than aspirin in
certain individuals.  Steroids are also used to treat inflammatory diseases.
     When sore muscles tense, they cause pain, inflammation, and spasm.
Skeletal muscle relaxants (for example, orphenadrine, aspirin, and caffeine
combination; meprobamate and aspirin combination; and chlorzoxazone and
acetaminophen combination) can relieve these symptoms.  Skeletal muscle
relaxants are often given in combination with an anti-inflammatory drug such
as aspirin.  Some doctors, however, believe that aspirin and rest are better
for alleviating the pain and inflammation of muscle strain than are skeletal
muscle relaxants.

RESPIRATORY DRUGS

     Antitussives

     Antitussives control coughs.  There are numerous over-the-counter
(nonprescription) antitussives available--most of them contain
dextromethorphan.  Codeine is a narcotic antitussive that is an ingredient in
many prescription cough medications.  These cough syrups must be absorbed into
the blood and must circulate and act on the brain before they relieve a cough.

     Expectorants

     Expectorants are used to change a nonproductive cough to a productive one
(one that brings up phlegm).  Expectorants are supposed to increase the amount
of mucus produced.  However, drinking water or using a vaporizer or humidifier
is probably more effective in increasing mucus production.  Popular
expectorant ingredients include ammonium chloride, guaifenesin, potassium
guaiacolsulfonate, and terpin hydrate.

     Decongestants

     Decongestants constrict blood vessels in the nose and sinuses to open up
air passages.  They are available as oral preparations, nose drops, and nose
sprays.  Oral decongestants are slow-acting but do not interfere with
production of mucus or movement of the cilia (special hairlike structures) of
the respiratory tract.  They can, however, increase blood pressure, so they
should be used cautiously by patients with high blood pressure.  Topical
decongestants (nose drops or spray) provide almost immediate relief.  They do
not increase blood pressure as much as oral decongestants, but they do slow
the movement of the cilia.
     People who use these products may also develop a tolerance for them.
Tolerance can be described as a need for ever-increasing dosages to achieve a
beneficial effect.  The additional disadvantage of developing tolerance is
that the risk of side effects increases as the dosage increases.  Topical
decongestants should not be used for more than a few days at a time.

     Bronchodilators

     Bronchodilators (agents that open airways in the lungs) and agents that
relax smooth-muscle tissue (such as that found in the lungs) are used to
improve breathing.  Theophylline and aminophylline are oral bronchodilators
commonly used to relieve the symptoms of asthma and pulmonary emphysema.
Albuterol and metaproterenol are inhalant bronchodilators, which act directly
on the muscles of the bronchi (breathing tubes).

     Antihistamines

     Histamine is a body chemical that, when released in the body, typically
causes swelling and itching.  Antihistamines counteract these symptoms of
allergy by blocking the effects of histamine.  For mild respiratory allergies,
such as hay fever, antihistamines can be used.  Diphenhydramine and other
antihistamines are relatively slow-acting.  Severe allergic reactions
sometimes require the use of epinephrine (which is not an antihistamine); in
its injectable form, it is very fast-acting.
     Some types of antihistamines are also used to prevent or treat the
symptoms of motion sickness.  Diphenhydramine and meclizine are examples of
drugs used specifically for this purpose.

VITAMINS AND MINERALS

     Vitamins and minerals are chemical substances that are vital to the
maintenance of normal body function.  Most people obtain enough vitamins and
minerals in their diet, but some people have vitamin deficiencies.  Serious
nutritional deficiencies lead to diseases such as pellagra and beriberi, which
must be treated by a physician.  People who have an inadequate or restricted
diet, people who have certain disorders or debilitating illnesses, and women
who are pregnant or breast-feeding are among those who may benefit from taking
supplemental vitamins and minerals.  However, even these people should consult
a doctor to see if a true vitamin deficiency exists.

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The material contained here is "FOR INFORMATION ONLY" and should not replace
the counsel and advice of your personal physician.  Promptly consulting your
doctor is the best path to a quick and successful resolution of any medical
problem.