DƯỢC LÍ Goodman & Gilman's The Pharmacological Basis of Therapeutics 12th, 2010

1886 if available. The USP maintains an electronic web site
that can be accessed for useful drug naming, classification,
and standards information (www.usp.org).
In the U.S., drug products also are coded under
the National Drug Code (NDC). The NDC originally
was established as an essential part of out-of-hospital
drug reimbursement under Medicare. In the U.S., the
NDC serves as a universal product identifier for drugs
used in humans. The current edition of the National
Drug Code Directory is limited to prescription drugs
and a few selected over-the-counter products. Each
drug product listed under the Federal Food, Drug, and
Cosmetic Act is assigned a unique 10-digit, 3-segment
number. This number, known as the NDC number,
identifies the labeler/vendor, product, and package size.
The labeler/vendor code is assigned by the FDA. The
second segment, the product code, identifies a specific
strength, dosage form, and formulation for a particular
drug company. The third segment, the package code,
identifies package sizes. Both the product and package
codes are assigned by the manufacturer.
In addition to classification of drugs by therapeutic
category, drugs also are grouped by control schedule.
Drug schedules in the U.S. are listed in Table AI–1
from schedule I to schedule V and are discussed above
under “Controlled Substances.”
The FDA also categorizes drugs that may be used
in pregnant women. These categories are similar to
those used in other countries and provide guidance
based on available science. The risk from a drug may be
throughout pregnancy or limited to a particular period
of fetal development. The categories range from A to
X, in increasing order of concern, as noted here:
APPENDIX I
PRINCIPLES OF PRESCRIPTION ORDER WRITING AND PATIENT COMPLIANCE
Pregnancy Category A: Adequate and well-controlled
studies have failed to demonstrate a risk to the
fetus in the first trimester of pregnancy (and there is
no evidence of risk in later trimesters). Because of
the obvious nature of the risk associated with the use
of medications during gestation, the FDA requires a
body of high-quality data on a drug before it can be
considered for Pregnancy Category A.
Pregnancy Category B: Animal reproduction studies
have failed to demonstrate a risk to the fetus, and
there are no adequate and well-controlled studies in
pregnant women, OR animal studies have shown an
adverse effect, but adequate and well-controlled
studies in pregnant women have failed to demonstrate
a risk to the fetus in any trimester.
Pregnancy Category C: Animal reproduction studies
have shown an adverse effect on the fetus, and
there are no adequate and well-controlled studies in
humans, but potential benefits may warrant use of
the drug in pregnant women despite potential risks.
Pregnancy Category D: There is positive evidence
of human fetal risk based on adverse reaction data
from investigational or marketing experience or
studies in humans, but potential benefits may warrant
use of the drug in pregnant women despite
potential risks.
Pregnancy Category X: Studies in animals or
humans have demonstrated fetal abnormalities,
and/or there is positive evidence of human fetal risk
based on adverse reaction data from investigational
or marketing experience, and the risks involved in
use of the drug in pregnant women clearly outweigh
potential benefits.
Physicians should realize that the pregnancy categories
by themselves provide little guidance for the physician
treating pregnant women. For example, angiotensinconverting
enzyme (ACE) inhibitors such as captopril
cause developmental toxicity (Category X) only after
the first trimester. Physicians’ primary responsibility
remains treating the pregnant patient. However, the
risks of withholding treatment to the mother because of
possible risks to the fetus have to be considered as well.
Drugs also are grouped by their potential for misuse
under British and U.N. legal classifications as class A, B,
or C. The classes are linked to maximum legal penalties
in a descending order of severity, from A to C.
COMPLIANCE
Compliance may be defined as the extent to which the
patient follows a regimen prescribed by a healthcare
professional. The assumption that the doctor tells the
patient what to do and then the patient meticulously
follows orders is unrealistic. The patient is the final and
most important determinant of how successful a therapeutic
regimen will be and should be engaged as an
active participant who has a vested interest in its success.
Whatever term is used—compliance, adherence,
therapeutic alliance, or concordance—physicians must
promote a collaborative interaction between doctor and
patient in which each brings an expertise that helps to
determine the course of therapy. The doctor is the medical
expert; the patient is the expert on himself and his
beliefs, values, habits, and lifestyle. The patient’s qualityof-life
beliefs may differ from the clinician’s therapeutic
goals, and the patient will have the last word every time
when there is an unresolved conflict.