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给 药
(一)
中国医科大学护理学院
王健
Medications
(one)
A medication is a substance
administered for the diagnosis, cure,
treatment, mitigation (relief), or
prevention of disease. In the health
care context, the words medication
and drug are generally used
interchangeably. The term drug
also has the connotation of an
illicitly obtained substance such as
heroin, cocaine, or amphetamines.
In the United States and Canada,
medications are usually dispensed
on the order of physicians and
dentists. In some US states, specially
qualified nurse-practitioners and
physician’s assistants may prescribe
drugs. The written direction for the
preparation and administration of a
drug is called a prescription.
One drug can have as many as
four kinds of names: its generic
name, official name, chemical
name, and trademark or brand
name. The generic name is given
before a drug becomes official. The
official name is the name under
which it is listed in one of the
official publications (eg, the United
States Pharmacopeia).
The chemical name is the
name by which a chemist knows it;
this name describes the
constituents of the drug precisely.
The trademark, or brand name, is
the name given by the drug
manufacturer. Because one drug
may be manufactured by several
companies, it can have several
trade names.
Medications are often
available in a variety of forms.
They are aerosol spray or foam,
aqueous solution, aqueous
suspension, caplet, capsule,
cream, elixir, extract, gel or jelly,
liniment, lotion, lozenge(troche),
ointment (salve, unction), paste,
pill, powder, suppository, syrup,
tablet, tincture, transdermal patch.
Pharmacology is the study of the
effect of drugs on living organisms.
Pharmacy is the art of preparing,
compounding, and dispensing
drugs. The word also refers to the
place where drugs are prepared
and dispensed. Drugs are prepared
by a pharmacist, a person licensed
to prepare and dispense drugs and
to make up prescriptions.
A clinical pharmacist is a
specialist who often guides
the physician in prescribing
drugs. A pharmacy technician
is a member of the health
team who in some states
administers drugs to clients.
DRUG STANDARDS
•Drugs may have natural (eg, plant,
mineral, and animal) sources or they
may be synthesized in the laboratory.
For example, digitalis and opium are
plant derived, iron and sodium chloride
are minerals, insulin and vaccines have
animal or human sources, and the
sulfonamides and propoxyphene
hydrochloride (the analgesic Darvon) are
the products of laboratory synthesis.
•Drugs vary in strength and
activity. Drugs derived from plants,
for example, vary in strength
according to the age of the plant,
the variety, the place in which it is
grown, and the method by which
it is preserved. Drugs must be
pure and of uniform strength if
drug dosages are to be
predictable in their effect.
•Drug standards have therefore been
developed to ensure uniform quality. In
the United States, official drugs are those
so designated by the Federal Food, Drug,
and Cosmetic Act. These drugs are
officially listed in the United States
Pharmacopeia (USP) and described
according to their source, physical and
chemical properties, tests for purity and
identity, method of storage, assay,
category, and normal dosages.
•A Pharmacopoeia (also spelled
pharmacopeia) is a book containing a
list of products used in medicine, with
descriptions of the product, chemical
tests for determining identity and
purity, and formulas and prescriptions.
The United States’ National
Formulary lists drugs and their
therapeutic value and can include
drugs that may still be used but not
listed in the USP.
•Pharmacopoeias and formularies are
invaluable reference sources for nurses
and nursing students. Nurses not only
administer thousands of medications but
also are responsible for assessing their
effectiveness and recognizing
unfavorable reactions to drugs. Since it
is impossible to commit to memory all
pertinent information about a very large
number of drugs, nurses must have a
reliable reference readily available.
LEGAL ASPECTS OF DRUG ADMINISTRATION
• The administration of drugs in both the
United States and Canada is controlled by law.
Nurses need to (a) know how nursing practice
acts in their areas define and limit their
functions and (b) be able to recognize the
limits of their own knowledge and skill. To
function beyond the limits of nursing practice
acts or one’s ability is to endanger clients’ lives
and leave oneself open to malpractice suits.
•Under the law, nurses are responsible for
their own actions regardless of whether
there is a written order. If a physician
writes an incorrect order (eg, Demerol 500
mg instead of Demerol 50 mg), a nurse
who administers the written incorrect
dosage is responsible for the error.
Therefore, nurses should question any
order that appears unreasonable and
refuse to give the medication until the
order is clarified.
•Another aspect of nursing practice
governed by law is the use of
controlled substances. In hospitals,
controlled substances are kept in a
locked drawer, cupboard, medication
cart, or computer-controlled
dispensing system. Agencies have
special forms for recording the use
of controlled substances.
•The information required usually
includes the name of the client, the
date and time of administration, the
name of the drug, the dosage, and
the signature of the person who
prepared and gave the drug. The
name of the physician who ordered
the drug may also be part of the
record.
•Included on the record are the controlled
substances wasted during preparation. In
most agencies, counts of controlled
substances are taken at the end of each
shift. The count total should tally with the
total at the end of the last shift minus the
number used. If the totals do not tally, the
discrepancy must be reported immediately.
In facilities that use a computerized
dispensing system, manual counts are not
required, because the dispensing system
runs a continuous count; however,
discrepancies must be accounted for.
EFFECTS OF DRUGS
1.The therapeutic effect of a drug, also
referred to as the desired effect, is the
primary effect intended, that is, the
reason the drug is prescribed. For
example, the therapeutic effect of
morphine sulfate is analgesia, and the
therapeutic effect of diazepam is relief of
anxiety. The kinds of therapeutic actions
are as follows: palliative, curative,
supportive, substitutive,
chemotherapeutic and restorative.
2.A side effect, or secondary effect, of a
drug is one that is unintended. Side
effects are usually predictable and may
be either harmless or potentially harmful.
For example, digitalis increases the
strength of myocardial contractions
(desired effect), but it can have the side
effect of inducing nausea and vomiting.
Some side effects are tolerated for the
drug’s therapeutic effect; more severe
side effects, also called adverse effects,
may justify the discontinuation of a drug.
3.Drug toxicity (deleterious effects
of a drug on an organism or
tissue) results from overdosage,
ingestion of a drug intended for
external use, and buildup of the
drug in the blood because of
impaired metabolism or excretion
(cumulative effect).
Some toxic effects are apparent
immediately; some are not apparent
for weeks or months. Fortunately,
most drug toxicity is avoidable if
careful attention is paid to dosage and
monitoring for toxicity. An example of
a toxic effect is respiratory depression
due to the cumulative effect of
morphine sulfate in the body.
4.A drug allergy is an
immunologic reaction to a drug.
When a client is first exposed to
a foreign substance (antigen), the
body may react by producing
antibodies. A client can react to a
drug as to an antigen and thus
develop symptoms of an allergic
reaction.
•Allergic reactions can be either mild
or severe. A mild reaction has a
variety of symptoms, which are skin
rashes, pruritus, angioedema, rhinitis,
lacrimal tearing, nausea, vomiting,
wheezing and dyspnea, diarrhea. An
allergic reaction can occur anytime
from a few minutes to 2 weeks after
the administration of the drug.
•A severe allergic reaction usually
occurs immediately after the
administration of the drug; it is called
an anaphylactic reaction. This
response can be fatal if the symptoms
are not noticed immediately and
treatment is not obtained promptly. The
earliest symptoms are acute shortness
of breath, acute hypotension, and
tachycardia.
5.Drug tolerance exists in a person
who has unusually low physiologic
activity in response to a drug and
who requires increases in the dosage
to maintain a given therapeutic effect.
Drugs that commonly produce
tolerance are opiates, barbiturates,
ethyl alcohol, and tobacco.
•A cumulative effect is the increasing
response to repeated doses of a
drug that occurs when the rate of
administration exceeds the rate of
metabolism or excretion. As a result,
the amount of the drug builds up in
the client’s body unless the dosage
is adjusted. Toxic symptoms may
occur.
•An idiosyncratic effect is
unexpected and individual.
Underresponse and overresponse
to a drug may be idiosyncratic. Also,
the drug may have a completely
different effect from the normal one
or cause unpredictable and
unexplainable symptoms in a
particular client.
6.A drug interaction occurs when the
administration of one drug before, at
the same time as, or after another
drug alters the effect of one or both
drugs.
•The effect of one or both drugs may
be either increased (potentiating or
synergistic effect) or decreased
(inhibiting effect).
•Drug interactions may be beneficial
or harmful. For example, probenecid,
which blocks the excretion of
penicillin, can be given with penicillin
to increase blood levels of the
penicillin for longer periods
(potentiating effect). Two analgesics,
such as aspirin and codeine, are
often given together because
together they provide greater pain
relief (additive effect).
•In addition, certain foods may
interact adversely with a
medication. See Table 44-1.
7.Iatrogenic disease (disease
caused unintentionally by
medical therapy) can be due to
drug therapy. Hepatic toxicity
resulting in biliary obstruction,
renal damage, and malformations
of the fetus as a result of specific
drugs taken during pregnancy
are examples.
DRUG MISUSE
1.Drug misuse is the improper use of common
medications in ways that lead to acute and
chronic toxicity. Both over-the-counter drugs
and prescription drugs may be misused.
Laxatives, antacids, vitamins, headache
remedies, and cough and cold medications are
often self-prescribed and overused. Most
people suffer no harmful effects from these
drugs, but some people do. A persistent cough
may go undiagnosed until the underlying
problem becomes serious and advanced.
2.Drug abuse is inappropriate intake of
a substance, either continually or
periodically. By definition, drug use is
abusive when society considers it
abusive. For example, the intake of
alcohol at work may be considered
alcohol abuse, but intake at a social
gathering may not. Drug abuse has two
main facets, drug dependence and
habituation.
•Drug dependence is a person’s
reliance on or need to take a drug
or substance. The two types of
dependence, physiologic and
psychologic, may occur separately
or together.
a.Physiologic dependence is due
to biochemical changes in body
tissues, especially the nervous
system. These tissues come to
require the substance for normal
functioning. A dependent person
who stops using the drug
experiences withdrawal
symptoms.
b.Psychologic dependence is
emotional reliance on a drug to
maintain a sense of well-being,
accompanied by feelings of need
or cravings for that drug. There
are varying degrees of
psychologic dependence, ranging
from mild desire to craving and
compulsive use of the drug.
•Drug habituation denotes a mild
form of psychologic dependence.
The individual develops the habit
of taking the substance and feels
better after taking it. The
habituated individual tends to
continue the habit even though it
may be injurious to health.
3.Illicit drugs, also called street drugs,
are those sold illegally. Illicit drugs are of
two types: (a) drugs unavailable for
purchase under any circumstances, such
as heroin (in the United States), and (b)
drugs normally available with a
prescription that are being obtained
through illegal channels. Illicit drugs
often are taken because of their moodaltering effect; that is, they make the
person feel happy or relaxed.
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