In its entirety, pharmacology embraces the knowledge of the history, source, physical and chemical properties,
compounding, biochemical and physiological effects, mechanisms of action, absorption, distribution, biotransformation and
excretion, and therapeutic and other us of drugs. Since a drug is broadly defined as any chemical agent that affects living
process, the subject of pharmacology is obviously quite extensive.
For the physician and the medical student, however, the scope of pharmacology is less expansive than indicated by the
above definitions. The clinician is interested primarily in drugs that are uful in the prevention, diagnosis, and treatment
of human dia, or in the prevention of pregnancy. His study of the pharmacology of the drugs can be reasonably limited
to tho aspects that provide the basis for their rational clinical u. Secondarily, the physician is also concerned with
chemical agents that are not ud in therapy but are commonly responsible for houhold and industrial poisoning as well as
environmental pollution. His study of the substances is justifiably restricted to the general principles of prevention,
recognition, and treatment of such toxicity or pollution. Finally, all physicians share in the responsibility to help resolve
the continuing sociological problem of the abu of drugs.
A brief consideration of its major subject areas wil属猴和属鼠的合不合
l further clarify how the study of pharmacology is best approached经典华语歌曲
from the standpoint of the specific requirements and interests of the medical students and practitioners. At one time, it
was esntial for the physician to have a broad botanical knowledge, since he had to lect the proper plants from which to
prepare his own crude medicinal preparations. However, fewer drugs are now obtained from natural sources, and, more
importantly, most of the are 孙悦婷
highly purified or standardized and differ little from synthetic chemicals. Hence, the interests
of the clinician in pharmacognosy are correspondingly limited. Nevertheless, scientific curiosity should stimulate the physician
to learn something of the sources of drugs, and this knowledge often proves practically uful as well as interesting. He will
find the history of drugs of similar value.
The preparing, compounding, and dispensing of medicines at one time lay within the province of the physician, but this work
is now delegated almost completely to the pharmacist. However, to write intelligent prescription orders, the physician must have
some knowledge of the physical and chemical properties of drugs and their available dosage forms, and he must have a basic
familiarity with the practice of pharmacy. When the physician shirks his responsibility in this regard, he invariably fails to
translate his knowledge of pharmacology and medicine into prescription orders and medication best suited for the individual patient.
Pharmacokinetics deals with the absorptio
n, distribution, biotransformation, and excretion of drugs. The factors, coupled
with dosage, determine the concentration of a drug at its sites of action and, hence, the intensity of its effects as a function
of time. Many basic principles of biochemistry and enzymology and the physical and chemical principles that govern the active
and passive transfer and the distribution of substances across b梦见水流
iological membranes are readily applied to the understanding of
this important aspect of pharmacology.
The study of the biochemical and physiological effects of drugs and their mechanisms of action are termed as pharmacodynamics.
It is an experimental medical science that dates back only to the later half of the nineteenth century. As a border science,
pharmacodynamics borrows freely from both the subject matter and the experimental techniques of physiology, biochemistry,
microbiology, immunology, genetics, and pathology. It is unique mainly in that attention which is focud on the characteristics
of drugs. As the name implies, the subject is a dynamic one. The student who attempts merely to memorize the pharmacodynamic
properties of drugs is foregoing one of the best opportunities for correlating the entire field of preclinical medicine. For
example, the actions and effects of the saluretic agents can be fully understood only in terms of the basic principles of renal
physiology and of the pathogenesis of edema. Converly, no greater insight into normal and abnormal renal physiology can be
gained than by the study of the pharmacodynamics of the saluretic agents.
Another ramification of pharmacodynamics is the correlation of the actions and effects of drugs with their chemical
structures. Such structure-activity relationships are an integral link in the analysis of drug action, and exploitation of
the relationships among established therapeutic agents has often led to the development of better drugs. However, the
correlation of biological activity with chemical structure is usually of interest to the physician only when it provides
the basis for summarizing other pharmacological information.
The physician is understandably interested mainly in the effects of drugs in man. This emphasis on clinical pharmacology is
justified, since the effects of drugs are often characterized by significant interspecies variation, and since they may be
further modified by dia. In addition, some drug effects, such as tho on mood and behavior, can be adequately studied only
in man. However, the pharmacological evaluation of drugs in man may be limited for technical, legal, and ethical reasons, and
the choice of drugs must be bad in part on their pharmacological evaluation in animals. Conquently, some knowledge of animal
pharmacology and comparative pharmacology is helpful in deciding the extent to which claims for a drug bad upon studies in
animals can be reasonably extrapolated to man.
Pharmacot
herapeutics deals with the u of drugs in the prevention and treatment of dia. Many drugs stimulate or
depress biochemical or physiological function in man in a sufficiently reproducible manner to provide relief of symptoms or,
ideally, to alter favorably the cour of dia. Converly, chemicotherapeutic agents are uful in therapy becau they
have only minimal effects on man but can destroy or eliminate parasites. Whether a drug is uful for therapy is crucially
dependent upon its ability to produce its desired effects with only tolerable undesired effects. Thus, from the standpoint
of the physician interested in the therapeutic us of a drug, the lectivity of its effects is one of its most important
characteristics. Drug therapy is rationally bad upon the correlation of the actions and effects of drugs with the
physiological, biochemical, microbiological, immunological, and behavioral aspects of dia. Pharmacodynamics provides one
of the best opportunities for this correlation during the study of both the preclinical and the clinical medical sciences.
Toxicology is the aspect of pharmac古巴共和国
ology that deals with the adver effects of drugs. It is concerned not only with drugs
ud in therapy but also with the many other chemicals that may be re内蒙古高考状元
sponsible for houhold, environmental, or industrial
intoxication. The adver effects of the pharmacological agents employed in therapy are properly considered an integral part
of their total pharmacology. The toxic effec力挽狂澜
ts of other chemicals are such an extensive subject that the physician must
usua浮躁小说
lly confine his attention to the general principles applicable to the prevention, recognition, and treatment of drug
poisonings of any cau.
