Routes of Drug Administration Overview

Study Notes

Routes of Drug Administration

Various routes exist for administering drugs, impacting their absorption and effects.
Routes include sublingual, inhalation, oral, transdermal patch, rectal, and topical.
Parenteral routes involve injection (e.g., IV, IM, SC).

Factors Affecting Choice of Route

Drug form influences the choice of route.
Physical and chemical properties of the drug are key considerations.
Rapidity of response is a critical factor.
Animal behavior and the disease's nature and location play roles.

Routes of Drug Administration - Details

A) Body Orifices: Includes oral, nasal, respiratory, rectal, vaginal, urethral, and intramammary routes.
1) Oral Route (Per Os): Drugs given orally should be palatable, non-irritant, stable at intestinal and gastric pH, unaffected by digestive juices, and adequately absorbed.
Advantages: Convenient, inexpensive, variety of forms, and safe.
Disadvantages: Difficult handling, inappropriate for unconscious animals, unsuitable during gastrointestinal (GIT) disturbances, some drugs destroyed by gastric acidity, enzymes, or decomposed in the GIT.
2) Nasal Route (Nasal drops): Local effect, used for anti-inflammatory drops (e.g., rhinitis) and decongestant drops (vasoconstriction).
3) Respiratory Route (Inhalation): Drug administration via inspired air, using forms like gas, volatile liquids (ether), or aerosols (e.g., isoprenaline spray). Used for local effects like bronchodilation (e.g., asthma) and systemic effects like anesthesia. Rapid onset of action is an advantage.
4) Rectal Route (Per rectum): Drug is administered as suppositories or enemas with local effects (e.g., purgative, treating enteritis, and piles or treating infections with antibiotics via suppositories). Absorption is slow, suitable when other routes are unsatisfactory.
5) Vaginal Route: Uses are localized treatment for vaginal and uterine affections using pessaries or uterine tablets.
6) Urethral Route: Drug is introduced using a catheter for localized treatment of urethra, prostate, and urinary bladder affections.
7) Intramammary Route: involves drug administration using a teat catheter (syphon) or cannula for udder conditions (mastitis).

Parenteral Routes (By Injection)

Drugs introduced into the body using syringes.
Useful when oral administration is ineffective due to destruction by gastric acidity, enzyme, or impaired absorption.
In conditions like nausea, vomiting due to irritant action, or severe gastrointestinal issues. Useful in emergencies or for rapidly raising drug concentration.

Intravenous (I/V), Intramuscular (I/M), Subcutaneous (S/C), Intradermal (I/D), Intraperitoneal (I/P), Intracardiac, and Intra-articular

1) Intravenous (I/V): Fastest action, high risk due to toxicity.
2) Intramuscular (I/M): Slower action, good for moderate irritant drugs.
3) Subcutaneous (S/C): Slower absorption than intramuscular, less risk of irritation.
4) Intradermal (I/D): Introduction of drug under the skin, used for testing.
5) Intraperitoneal (I/P): Used for rapidly absorbing drugs when other routes are unavailable (e.g., laboratory animals).
6) Intracardiac: Emergency route for rapid drug administration directly into the heart.
7) Intra-articular: Administration into joints, used to treat joint inflammation.

Epidural and Topical (Local)

8) Epidural: Local anesthetic injections into the epidural space for regional anesthesia.
c) Topical (Local): Drugs placed on the skin or mucous membranes; used for localized effects, such as counterirritants, anti-inflammatory agents, and antiseptics. Absorption is relatively slow through skin compared to some other routes, though vehicle addition may enhance absorption.