Clinical Relevance and Dosing Regimes.

Question 1

What is aim of drug administration?

Answer 1

To get a particular concentration of the drug at the site of infection.

Question 2

Do we always want a drug to reach the site of infection quickly?

Answer 2

Sometimes we will want the drug to get to the infection site very quickly.

Other times it does not matter how long it takes for the drug to get there.

Question 3

What influences a drugs route of administration?

Answer 3

The type of infection and its location.

Question 4

How can we get a drug to be absorbed into the tissues?

Answer 4

By setting up a concentration gradient.

Question 5

What kind of concentration gradient do we need to set up to ensure that drug absorption occurs?

Answer 5

Where the drug is in high concentration in the blood and low concentration on the tissues.

Question 6

Why do we need a drug to be in high concentration in the blood if it is to be absorbed in the tissues?

Answer 6

As the drug will want to flow from the blood and enter the tissues.

Question 7

What is the rate of drug absorption?

Answer 7

The time it takes for the drug to move from the blood to the tissues.

Question 8

Why do we use different routes of administration for different drugs?

Answer 8

Because we want different drugs to stay in the system for different amounts of time.

Question 9

Can the same does absorption rates depending on how it is administered?

Answer 9

Yes.

Question 10

What type of administration has the highest rate of absorption?

Answer 10

Intravenous administration.

Question 11

What type of administration has the lowest rate of absorption?

Answer 11

Intrarectal administration.

Question 12

Why do we use different doses of drugs?

Answer 12

As the dose depends on the species/breed of the animal.

Question 13

What dictates the dose of the drug we use?

Answer 13

The weight of the animal in kilograms.

Question 14

What is the formula for drug injection?

Answer 14

Miligrams per kilogram (mg/Kg).

Question 15

Why is it better to take the metabolic bodyweight of an animal, rather than use its bodyweight in Kg’s?

Answer 15

As it takes into account the physiological differences of different species/ breeds.

Question 16

How do we calculate the metabolic bodyweight of an animal?

Answer 16

We take the logarithm of the bodyweight.

Question 17

Why does the metabolic bodyweight allow us to give a much more effective dose?

Answer 17

As it takes into account the physiology of the animal.

Question 18

What is allometric scaling?

Answer 18

The correlation between pharmokinetics and the metabolism and elimination of the drug.

Question 19

Drug elimination is correlated with what physiological characteristic?

Answer 19

Cardiac output (except for drugs that are metabolised very quickly).

Question 20

What does allometric scaling allow us to calculate?

Answer 20

The pharmokinetics, but not the pharmacodynamics.

This means we can see how the drug gets to the site of infection, but not how it works.