form is not swallowed. The tablet is to be dissolved under the tongue (sublingual) or in
the pouch of the cheek (buccal). The drugs administered in this manner are rapidly
absorbed and have the advantage of bypassing the gastrointestinal tract. Nitroglycerin,
for heart patients, in tablet form is more likely the most frequently administered
(3) Rectal. Drugs administered by the rectal route may have a local effect
(as for hemorrhoids) or a systemic effect (as in the prevention of nausea and vomiting).
The rectal route is convenient to use in pediatric patients (children) or in patients who
are unconscious or vomiting. The amount of drug absorbed in the rectal route is usually
less than if the drug were administered orally. The absorption of drugs administered
rectally is unpredictable and can vary among patients.
(4) Vaginal/urethral. Drugs administered using the vaginal/urethral route are
used for their local effect. That is, they are usually given to treat an infection or other
pathological condition. Drugs administered in this route should not be irritating since
systemic absorption may occur.
(5) Inhalation. Drugs administered by inhalation have either may a local or
systemic effect. Anesthetics, like nitrous oxide, are inhaled and exert their effect after
absorption into the circulatory system. Sprays for nasal congestion have their effect on
the tissue in the nose and do not necessarily enter the general circulation.
(6) Topical. The topical route is probably the oldest route of administration.
Topical medications are applied directly upon the skin. As long as the skin is intact (not
broken or cut), drugs applied in this manner exert a local effect. The base (vehicle)
used to carry the ingredients in the local preparation can influence the action of the
drug. For example, dimethylsulfoxide (DMSO) will readily penetrate the skin and carry
the active ingredient along with it.
(7) Parenteral. The term parenteral literally means to avoid the gut
(gastrointestinal tract). Thus, parenterals are injectable drugs that enter the body
directly and are not required to be absorbed in the gastrointestinal tract before they
show their effect. Parenteral routes of administration usually have a more rapid onset of
action (show their effects more quickly) than other routes of administration. Parenteral
products must be sterile (free from living microbes). The parenteral route of
administration does have its disadvantages: it hurts, it is not a convenient route, and
once administered the injected drug cannot be retrieved.
(a) Intravenous (IV). The injection of a drug directly into the patient's
veins is the most rapid route of administration. This type of parenteral route results in
the most rapid onset of action.
(b) Intraarterial. In this parenteral route, the drug is injected directly
into the patient's arteries. This route is not frequently used.