ANSWERS

1. Define local administration.
   Local administration is the application of a drug directly to the part of the body affected; i.e. skin or mucous membranes.
2. By what name are locally administered drugs commonly known?
   Topical preparations.
3. List 8 types of topical preparation.
   • Aerosols.
   • Creams.
   • Enemas.
   • Lotions.
   • Ointments.
   • Pessaries.
   • Powders are sometimes also used (flea powder, wound powder) but these tend to fall off and therefore are not terrible effective for external use).
   • Suppositories.
4. Define systemic administration.
   Systemic administration refers to orally, parentally (by injection generally, but can refer to any route other than oral), intracardiac or epidural routes enabling a drug to act upon an internal organ or throughout the entire body. NB. Two less common routes of systemic administration are intra-articular (injection into a joint cavity) and intra-thecal (injection into the central nervous system).
5. What medical condition would contra-indicate the oral administration of a drug and why?
   A vomiting animal should not be given oral preparations due to the risk of aspiration pneumonia or choking. In addition the drug may be vomited before it has time to be absorbed and is therefore useless.
6. In addition to vomiting, list 3 other reasons why oral administration of a drug may not be a suitable route (clue - these are associated with the drug rather than the patient).
   • Some drugs are unstable in gastric acid (this is why some tablets should not be crushed since this destroys their protective outer layer).
   • The gut enzymes destroy drugs such as penicillin G and insulin.
   • Some drugs may be inactivated by the liver before they have a chance to reach the systemic circulation.
7. These abbreviations are commonly used in practice: I/V, I/M, S/Q (or S/C), I/P & P/O. What do they stand for?
   • I/V = Intravenous.
   • I/M = Intramuscular.
   • S/Q or S/C = Subcutaneous.
   • I/P = Intraperitoneal.
   • P/O = Per os (Latin for by mouth)
8. Of the routes of drug administration listed in Q6, which is the fastest acting and why?
   The intravenous route is the quickest since the drug reaches the blood stream directly and therefore achieves a higher peak plasma concentration than any of the other routes listed.
9. What is the difference between a solution and a suspension? Explain why suspensions should never be injected.
   A solution is a liquid in which a solute has been dissolved within a solvent, while a suspension is a liquid in which particles of a substance are held but not dissolved. Suspensions should not be injected since the particles may cause a fatal capillary blockage in the lungs or brain.
10. Although the fastest route of action is often desirable, certain drugs may benefit from slower absorption. Explain why.
    Slower absorption means that a drug may maintain an effective concentration within the blood stream for a longer period of time. NB. The oral route is the slowest of all the drug routes listed in Q7.
11. What is a depot preparation?
    A depot preparation is a long acting injectable drug containing a combination of salts of varying solubility producing different rates of absorption. Examples include protamine zinc insulin and hormone implants.
12. What is nebulisation?
    Nebulisation is the inhalation of a very fine mist of droplets from an atomiser. This is not an ideal drug route due to the risk self-inhalation by the member of staff administering the preparation.