8. Mode of administration. This has a definite
impact on the dose. Example: Injections
may require smaller doses.
METHODS OF ADMINISTERING
Drugs are introduced into the body by dif-
ferent routes, each serving a specific purpose.
Oral administration of medications is the most
common method. Advantages are (1) conven-
ience, (2) economy, (3) the drug need not be ab-
solutely pure or sterile, and (4) a wide variety of
dosage forms are available. Oral medications in-
clude tablets, capsules, liquids, and suspensions.
Disadvantages include (1) inability of some pa-
tients to swallow, (2) slow absorption, and (3) par-
tial or complete destruction by the digestive
system. Other routes associated closely with
oral administration are SUBLINGUAL and
SublingualThe drug is placed under the
tongue and rapidly absorbed directly into
the blood stream. Example: Nitroglycerin
BuccalThe drug is placed between the
cheek and gum and is quickly absorbed
directly into the blood stream.
Parenteral medications are those introduced
by injection. All drugs used by this route must
be pure, sterile, pyrogen-free (pyrogens are prod-
ucts of the growth of microorganisms), and in a
liquid state. There are several types of parenteral
SubcutaneousThe agent is injected just
below the skins cutaneous layers. Exam-
IntradermalThe drug is injected within
the dermis. Example: Purified protein
IntramuscularThe drug is injected into
the muscle. Example: Procaine penicillin G
IntravenousThe drug is introduced
directly into the vein: Example: In-
Intrathecal/intraspinalThe drug is in-
troduced into the subarachnoid space of
the spinal column.
Inhalation is the introduction of medications
through the respiratory system in the form of a
gas, vapor, or powder. Inhalation is divided into
three major types:
Vaporization This is where the drug is
changed from a liquid or solid to a gas or
vapor by the use of heat, such as steam
Gas inhalationIt is almost entirely
restricted to anesthesia.
NebulizationThe drug is nebulized into
minute droplets by the use of compressed
Ointments, creams, lotions, and shampoos are
examples of topical preparations. Topical applica-
tion serves two purposes: (1) local effect-the drug
is intended to relieve itching, burning, or other
skin conditions without being absorbed into the
bloodstream and (2) systemic effectthe drug is
absorbed through the skin into the bloodstream.
Example: Nitroglycerin paste
The rectal method is preferred to the oral route
when there is danger of vomiting or when the pa-
tient is unconscious, uncooperative, or mentally
Suppositories, creams, or tablets are examples
of vaginal preparations which are inserted into the
vagina to produce a local effect.
The definition of a drug is any chemical
substance that has an effect on living tissue but