Routes of administration

Question 1

List the various routes of administration of drugs.

Answer 1

• Oral
• Sublingual
• Rectal
• Transdermal
• Inhalation
• Topical
• Parenteral

Question 2

Oral

Answer 2

Offers maximal convenience; absorption is often slower. Subject to the first-pass effect, in which a significant amount of the agent is metabolized in the gut wall, portal circulation, and liver before it reaches the systemic circulation

Question 3

Buccal and sublingual (not swallowed

Answer 3

Direct absorption into the systemic venous circulation, bypassing the hepatic portal circuit and first-pass metabolism

Question 4

Intravenous

Answer 4

Instantaneous and complete absorption (by definition, bioavailability is 100%). Potentially more dangerous

Question 5

Intramuscular

Answer 5

Often faster and more complete (higher bioavailability) than with oral administration. Large volumes may be given if the drug is not too irritating. First-pass metabolism is avoided

Question 6

Subcutaneous

Answer 6

Slower absorption than the intramuscular route. First-pass metabolism is avoided.

Question 7

Rectal (suppository)

Answer 7

The rectal route offers partial avoidance of the first-pass effect. Larger amounts of drug and drugs with unpleasant tastes are better administered rectally than by the buccal or sublingual routes

Question 8

Inhalation

Answer 8

Route offers delivery closest to respiratory tissues (eg, for asthma). Usually very rapid absorption (eg, for anesthetic gases)

Question 9

Topical

Answer 9

The topical route includes application to the skin or to the mucous membrane of the eye, ear, nose, throat, airway, or vagina for local effect

Question 10

Transdermal

Answer 10

The transdermal route involves application to the skin for systemic effect. Absorption usually occurs very slowly (because of the thickness of the skin), but the first-pass effect is avoided