Test 1: lecture 18

Question 1

Name three routes of administration that result in essentially instantaneous absorption.

Question 2

Identify two advantages and two disadvantages of oral administration.

Answer 2

1st pass

Question 3

Will a weak base with a pKa of 8.4 be best absorbed in the stomach or the intestine?
Why?

Question 4

After oral administration of 10 mg of a drug, 50% is absorbed and 40% of the amount absorbed is metabolized by the first pass effect. What is the bioavailable dose or
bioavailability of this drug? Please be sure to provide units for your answer.

Question 5

A 10 mg/Kg dose of a drug is given by intravenous injection to a 20 Kg dog. What is the
volume of distribution of the drug if the plasma concentration is 0.1 mg/L (assume the drug
is instanteously distributed)? What is the volume of distribution if the same drug is given orally and only 50% of the drug was absorbed (the concentration of drug at time = 0 is 0.1 mg/L)? Be sure to provide units.

Question 6

How much of a drug is eliminated after 4 half-lives? What will happen to elimination of the drug if the system becomes saturated?

Question 7

You have started a patient on a new drug. Each dose introduces 0.04 ng/mL of drug after redistribution and prior to elimination. This drug is administered at 24 h intervals and has a half-life of 24 h. What will the concentrations of drug be after each of the first six doses?

Question 8

If you wanted to reduce the difference between peak and trough levels that occur with
repeated administration of a drug, how would you adjust the dose and dose interval?
Note: You don’t want to increase the plateau concentration (plateau is the average of peak and trough levels).

1. Increase dose
2. Decrease dose
3. Do not change dose
4. Increase the interval between doses (give the drug less frequently)
5. Decrease the interval between doses (give the drug more frequently)
6. Do not change the interval

Question 9

When a patient is being given multiple drugs, there can be drug-drug interactions that
result from saturation of the system used for elimination. How would this affect the time
required to metabolize half of the drug?
1. Increase dose
2. Decrease dose
3. Do not change dose

How might you adjust the dosing regimen (dose or dose interval) to maintain therapeutic concentrations of the drug?
1. Increase the interval between doses (give the drug less frequently)
2. Decrease the interval between doses (give the drug more frequently)
3. Do not change the interval