(damage to the kidneys) results, the accumulation of these toxic products can result in
death.
(4) Toxic effects may not be limited to the person who is taking the drug. In
the past, it has been demonstrated that some drugs will cross the placental barrier and
enter the circulatory system of the fetus. Some drugs can exert serious effects on the
developing fetus. For example, the fetus may abort or be born with any number of
mental or physical defects. Since few mothers are willing to subject themselves and
their unborn children to drug testing, the effects of most drugs on the fetus are
unknown. Most of what is known about teratogenicity, fetal malformations, has been
learned either from experimental studies with animals or from the unfortunate
experiences of some mothers. The fetus is particularly susceptible to the adverse
effects of medications during the first three months after conception (the first trimester).
Unfortunately, many women do not realize they are pregnant until they are well into their
first trimester.
b. Allergic Reactions. A few individuals may be allergic, or hypersensitive, to a
drug. This allergy may arise because of a prior contact with a particular substance
called an allergen (it may even be the drug itself). This acquiring of an allergy is called
sensitization. You should understand that the symptoms of an allergy are not related to
the ordinary effects of the drug. Allergic reactions to a drug may range from a mildly
irritated skin rash to anaphylaxis (a fatal shock). It has been shown that penicillin, a
widely prescribed antibiotic, produces varying types of allergic reactions in from 1 to 10
percent of the patients who are administered the drug.
c. Side Effects. Most drugs do not produce only one single effect. Instead,
they may produce several physiological responses at the same time. For example,
antihistamines, drugs frequently used for their anti-allergic action tend to produce
drowsiness. In this case, drowsiness is a side effect of the antihistamines. With some
drugs, the side effects are so worrisome and inconvenient that the patient may stop
taking the medication.
d. Drug Dependence. All drugs have the potential of producing dependence,
the need to have that drug. There are two major types of dependence: psychological
and physiological.
(1) Psychological dependence may occur after a patient has been taking a
medication for a long time. With psychological dependence, the patient becomes so
convinced that he needs the drug (in order to continue to lead an improved life) that he
will go to great lengths to ensure that he receives the medication. Patients habituated
to amphetamines may demonstrate this type of dependence. Psychological
dependence is very difficult to treat.
(2) With physiological dependence, the patient's body develops a real need
for the drug over a long period. Since there is a physiological need for the drug, the
body reacts by going through withdrawal symptoms (that is, tremors, nausea, vomiting,
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