Chapter 2

CHAPTER 2
DRUGS
DEFINITION OF DRUGS:
• A drug is a chemical substance that brings about physical,

physiological, behavioral and/or psychological changes in a person
taking it.
• All medicines are drugs, but not all drugs are medicinal drugs.
•Drugs also help a person’s body and mind function better during an illness. But drugs
have to be taken correctly in order to do these things.
•The wrong drug or the wrong amount of the right one can make an illness, worse,
destroy blood cells, damage the body and may cause death.
•For this reason, most drugs can be legally purchased only with doctor’s written order
called prescription. Only a medical doctor can prescribe medicinal drugs.
•These drugs could be dangerous and must be used with care, according to the
doctor’s prescription. He gives direction on how much medicine to take and how often.
•The practice of taking drugs without proper medicinal supervision is called the non-
medical use of drugs or drug abuse.
TWO FORMS OF DRUGS:
1. Natural Drugs - include natural plant leaves, flowering tops, resin, hashish, opium,
and marijuana.
2. Synthetic/Artificial Drugs - are produced by clandestine laboratories which
include those drugs that are controlled by law because they are used in the medical
practice. Physicians prescribe them and are purchased in the legitimate outlets like
drugstores.
THE PRESCRIPTIVE DRUGS
•These are drugs requiring written authorization from a doctor to allow a

purchase. They are prescribed according to the individual’s age, weight and
height and should not be taken by anyone else. It is a personal requirement
and self-medication should be strictly avoided. The pharmacist should never
allow the consumer to request them knowingly without first consulting a
doctor.
•Once again strict emphasis of the following directions needs to be stated.
In addition to dosage, the physician indicates both when and for how long the
medicine should be taken. Theses directions are intended to safeguard the
patient from needlessly treating himself after his illness has been brought
under control or from prematurely stopping a drug because he thinks he is
well. Since the chemistry of the body is subtle and variable, only a physician
should have the responsibility of prescribing and directing the use of drugs in
the treatment of illnesses.
THE OVER-THE-COUNTER-DRUGS (OTC)
•These are non-prescription medicines, which may be purchased from any

pharmacy or drugstore without written authorization from a doctor. They are
use to treat minor and short term illnesses and any persistent condition
should be immediately referred to a physician. It should be strongly
emphasized that “directions” be closely followed and all precautions
necessarily taken to avoid complications.
OTCs must be used discriminately:
1. To avoid the dispensing of OTC to known identified habitual drug users.

2. To avoid complications, this is done by inquiring from the buyer of the
drugs as to the identity of the patient, the patient’s age and other information
such as pregnancy, hypertension, etc.
3. Counseling the patient so as to avoid the “self-medication” syndrome by
inquiring about the buyer’s source of information about the drug.
•OTC drugs are used for the prevention and symptomatic relief of minor ailments.
The precautions that must be observed when dispensing OTCs are the following:
1. the correct drug with the correct drug content is given to the correct patient in the
correct dosage form;
2. the pharmacist must counsel the patient to make sure that he/she takes the drugs
correctly; and
3. the pharmacist must be aware of and know about the possible toxicity’s possessed
by the OTC drugs to avoid food/drug incompatibilities and overdoses.
THE “SELF-MEDICATION SYNDROME”
• The “self-medication” syndrome is found in users and would be users of

drugs whose sources of information are people or literature other than
doctors, pharmacists and health workers. These could be members of the
family, relatives, and/or neighbors, all of whom may have previously used
the drug for their specific disease or disorder. Self-medication may work
against the good of the user because it can lead to intoxication and other
adverse reactions.
Possible outcomes of self-medication are:
1. Adverse reaction towards the drug, such as allergies that may be mild or severe.
2. Possible non-response of the patient to the drug effectively due to incorrect drug
usage.
3. Possible drug toxicities, through over dosage which may lead to severe reactions
such as nausea, vomiting, rashes, etc.
4. Possible habit-forming characteristics due to periodic use of the drugs even when
such are no longer needed.
MEDICINAL DRUGS AND DANGEROUS DRUGS :
DIFFERENCE
• Medicinal drugs – a substance which when taken into the human

body cures illness and/or relieves signs/symptoms of disease.
• Dangerous drugs – a substance affecting the central nervous system
which when taken into the human body brings about physical,
emotional or behavioral changes in a person taking it.
LEGAL CLASSIFICATION OF DRUGS:
A. R.A. 9165 – (Comprehensive Dangerous Drug Act of 2002)

B. P.D. 1619 – (Volatile Substances)
C. R.A. 6425 – (Classified as: Regulated and Prohibited)
• Under R.A. 9165, otherwise known as the Comprehensive Dangerous Drugs
Act of 2002, the term prohibited and regulated was changed into dangerous
drug with the following classification:
1. Immediate precursors – a chemical substance used in the clandestine
manufacturing process becomes incorporated in full or in part into the final
molecules of a substance under international control.
2. Essential chemicals – chemical substance used as reagent or
solvent in the illegal manufacture of controlled substances.
3. Narcotic, psychotropic and designer drugs
HOW DRUGS WORK?
• Most drugs act within a cell, rather than on the surface of a
cell or in the extracellular fluids of the body. Similar to
normal body chemicals, a drug enters a cell and participates
in a few steps of the normal sequence of a cellular process.
• Thus, drugs may later, interfere with or replace chemicals of
normal cellular life, hopefully for the betterment of the
person. The actual action of a particular drug depends on its
chemical make-up.
• When two drugs are taken together or within a few hours of each
other they may interact with unexpected results. This is one reason a
physician should always know the names of all drugs one is using.
• A dose of a drug is the amount taken at one time. The doses taken
become an extremely important part of drug abuse.
THE AMOUNT OF DRUG IN A DOSE CAN BE DESCRIBED AS:
1. Minimal dose – amount needed to treat or heal, that is, the smallest amount of a drug that
will produce a therapeutic effect.
2. Maximal dose – largest amount of a drug that will produce a desired therapeutic effect,
without any accompanying symptoms of toxicity.
3. Toxic dose – amount of drug that produces untoward effects or symptoms of poisoning.
4. Abusive dose – amount needed to produce the side effects and action desired by an
individual who improperly uses it.
5. Lethal dose – amount of drug that will cause death.
HOW DRUGS ARE ADMINISTERED?
THE COMMON METHODS OF ADMINISTRATION ARE
THE FOLLOWING:
1. Oral – this is the safest, most convenient and economical route whenever possible. There are however, drugs,
which cannot be administered this way because they are readily destroyed by the digestive juices or because they
irritate the mucous lining of the gastro-intestinal tract and induce vomiting.
2. Injection – this form of drug administration offers a faster response than the oral method. It makes use of a
needle or other device to deliver the drugs directly into the body tissue and blood circulation.
3. Inhalation – this route makes use of gaseous and volatile drugs, which are inhaled and absorbed rapidly through
the mucous of the respiratory tract.
4. Topical – this refers to the application of drugs directly to a body site such as the skin and the mucous membrane.
5. Iontophoresis – the introduction of drugs into the deeper layers of the skin by the use of special type of electric
current for local effect.
THE CONCEPT OF TOXICOLOGY
A DRUG MAY CAUSE EFFECTS BECAUSE OF ANY OF THE FOLLOWING:
1. Overdose – when too much of a drug in taken, there may be an over extension of its effects.
2. Allergy – some drugs cause the release of histamine giving rise to allergic symptoms such as dermatitis, swelling,
fall in blood pressure, suffocation and death.
3. Idiosyncrasy – for unexplained reasons, morphine, which sedates all men, stimulates and renders some women some
maniacal. Perhaps the phrase “catty woman” has pharmacological basis since most mammals are sedated by
morphine but some cats become extremely excited by it.
4. General Protoplasmic Poison Property – drugs are chemicals and some of them have the property of being general
protoplasmic poisons.
5. Side Effects – some drugs are not receptors for one organ but receptors of other organs as well. The effect in the
other organ may constitute a side effect, which is unwanted.
THE MEDICAL USES OF DRUGS
1. Take medicines on doctor’s advice. In prescribing medicine,
the doctor considers factors like age and weight, prevalent
signs and symptoms, severity of the disease, results of
laboratory examinations, route of administration tolerated by
patient, and presence of impairment in the organ or system.
The physician has always a reason for his orders.
2. When taking prescribed medicines, remember carefully the dosage,
manner of administration, frequency and time when to take it. Patient
must not trust his memory when taking medicine. The label of the
medicine should be read three times – once when medicine id remove
from cabinet, again before medicine is taken and a third time after it is
taken. Medicine should not be taken in the dark even if patient knows its
location.
3. If patient goes to more than one doctor, each one of them must know about all
the drugs being taken.
4. Avoid self-medication. Patient should not try to guess what is wrong with him
or to select his own medicines even if his symptoms seem to be familiar to
those of his neighbor.
5. Report any untoward effects of medicine to the physician. After taking
medicine, tell the doctor if any symptoms develop.
6. Patient should not take additional drugs without asking his physician.
7. See whether the medicine has expired or not.
8. Be sure that the label stays on a prescription container until all is used.
9. Store medicine in a safe, cool and dry place and out of reach of children.
10. Some people just purchase and use common drugs without knowing their
functions and contradictions. Thus, instead of being relieved of some symptoms,
their conditions are aggravated. Physicians share the same opinion that the
following drugs are better used under medical supervision to avoid harmful
consequences and habit formation.
11. Analgesics relieve pain. However, they may produce the opposite effects on
somebody who suffers form peptic ulcer or gastric irritation.
12. Antibiotics combat or control infectious organisms. Ingesting the same
antibiotics for a long time can result in allergic reactions and cause resistance to
the drug.
13. Antipyretics can lower body temperature or fever due to infection.
14. Antihistamines control or combat allergic reactions. People who on
antihistamine therapy must not operate or drive vehicles since these drugs can
cause drowsiness.
15. Contraceptives prevent the meeting of the egg cell and sperm cell or
prevent the ovary from releasing egg cells. Pregnant women must not take
birth control pills to avoid congenital abnormalities. This advice also
applies to women suffering from heart disease, varicose veins, breast
limps, goiter and anemia. The effectiveness of oral contraceptives may be
reduced when taken with antibiotic.
16. Decongestants relieve congestion of the nasal passages. Prolonged
used of these decongestants might include nasal congestion upon
withdrawal.
17. Expectorants ease the expulsion of mucus and phlegm from the
lungs and the throat. They are not drugs of choice for the newborn that
does not know to cough the phlegm out.
18. Laxatives stimulate defecation and encourage bowel movement. They should not be
given to pregnant women and those suffering from intestinal obstruction. Taking
purgatives (stronger than laxatives) unnecessarily might result in rupture of the intestines
or appendix if there is an obstruction. Constant use might make the intestines sluggish.
19. Sedatives and tranquilizers calm and quiet the nerves and relieve anxiety without
causing depression and clouding of the mind. Precautions must be taken in the use of
tranquilizers since they can cause impairment of judgement and dexterity.
20. Vitamins are food substances necessary for normal growth and development and
proper functioning of he body. A person who eats a balanced diet does not need
supplements. If they are found necessary, vitamin preparations should be taken with
meals. Vitamins should be treated as drugs since the body does not manufacture them.
Excessive dosage of vitamins A and D can be dangerous and harmful to health.
Excess of vitamin D can lead to nausea, diarrhea, and weight loss, calcification and
heart and kidney troubles. Too much vitamin A might result in symptoms of a disease
of the liver.
END OF CHAPTER 2

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CHAPTER 2

• A drug is a chemical substance that brings about physical,

•These are drugs requiring written authorization from a doctor to allow a

•These are non-prescription medicines, which may be purchased from any

1. To avoid the dispensing of OTC to known identified habitual drug users.

• The “self-medication” syndrome is found in users and would be users of

• Medicinal drugs – a substance which when taken into the human

A. R.A. 9165 – (Comprehensive Dangerous Drug Act of 2002)

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