Chap 2: Principles Of Drug Action

Question 1

Why is the half-life (T 1/2) of a drug important?

Answer 1

If drug is not completely metabolized and excreted then the levels of the drug can build up in the body.
It is a measure of now quickly the drug is eliminated from the body

Half life: how long a drug lasts in the body before you consume more

Question 2

What is the difference between enteral vs. Parenteral

Answer 2

Enteral: admin of drugs intended to be absorbed anywhere along the GI tract (mouth; convenient, flexibility in dosage, and painless. Other routes include…. suppositories; via rectum, sublingual, and drug solutions introduced via Indwelling gastric tube).

Parenternal: injectable form of admin of a substance that includes (IV, IM, SC, IT, and IO) IV is the fastest systemic circulation. IM is faster than oral route

Question 3

What is the principle organ for drug metabolism and the one for drug excretion?

Answer 3

Drug metabolism: liver
Drug excretion: kidneys

Question 4

What is a route of administration?

Answer 4

A portal of entry for the drug into the body
Ex: oral, injection, inhalation

Question 5

What factors may have an effect on drug absorption?

Answer 5

• Bioavailability; indicates the proportion of a drug that reaches the systemic circulation.
• blood flow to the site of absorption

Question 6

What is the first -pass effect and why is it important?

Answer 6

When a drug is administered orally and highly metabolized by the liver enzymes, most of the drugs activity is terminated in the passage through the liver before it reaches the general circulation and the rest of the body

It’s important because it allows you to determine the drug metabolism and any possible side effects

Question 7

What is the importance of ED? TI?

Answer 7

Therapeutic index (TI): how safe the drug is. (Smaller TI = more dangerous)

Effective Dose (ED): dose of drug at which half of the test subjects improve

Question 8

What is the definition of tolerance, potentiation, synergism?

Answer 8

Tolerance: decreasing intensity of response to a drug over time

Potentiation: special case of synergism in which one drug was no effect but can increase activity of the other drug

Synergism: occurs when 2 drugs act on the target organ via different mechanisms of action but their effects as a pair are greater than the sum of the separate effects of the drugs