Therapeutic drug monitoring

Question 1

What are the 4 main principles of pharmacokinetics

Answer 1

1. Absorption
2. Distribution
3. Metabolism
4. Excretion

Question 2

What are the 6 factors that affect the pharmokinetics of a drug

Answer 2

1. Age
2. Weight
3. Sex
4. Genetrics
5. Diseases
6. Drug interactions

Question 3

What is pharmacokinetics

Answer 3

studies how drugs move through the body, covering four primary processes: absorption, distribution, metabolism, and excretion

Question 4

What is the MEC

Answer 4

Minimum Effective Concentration: This is the minimum concentration of the drug above which therapeutic value of the drug is seen

Question 5

What is the MTC

Answer 5

Minimum Toxic Concentration: upper concentration above which the rate and severity of adverse effects become
unacceptable

Question 6

What could be the 4 possible causes of a lower than expected conc. of a drug in a patient

Answer 6

1. Incorrect dose given to the patient
2. Patient is non adherent to the patient
3. Rapid elimination of the drug
4. Time when the sample was taken is incorrect

Question 7

What are the possible causes of a higher than normal conc. of the drug

Answer 7

1. Error in the dose regimen
2. Decreased renal or hepatic function
3. Timing of the sampling
4. No response despite therapeutic conc. [tolerance]

Question 8

When can you safely say that you have reached the steady state

Answer 8

This occurs after at least 5 half lives after the last dose change

Question 9

What is therapeutic drug monitoring

Answer 9

Measurement of drug concentration in the body fluids

Question 10

Why is it important to do TDM

Answer 10

1. Avoid toxicity
2. Optimize the dose of the drug
3. Detect any changes in pharmacokinetics
4. Monitor adherence to the drugs

Question 11

What are the 6 main factors that influence pharmacokinetics

Answer 11

1. Age
2. Weight
3. Sex
4. Genetics
5. Disease
6. Drug interaction

Question 12

Which drugs are suitable for TDM

Answer 12

1. High interpatient variability in the plasma concentration
2. Narrow therapeutic range
3. When there is a high correlation between the plasma conc. and then clinical effect
4. Pharmacological effect is dependent on the plasma conc.
5. There is availability and it is cost effective

Question 13

What are the factors related to a patient that indicate TDM

Answer 13

1. Lack of a clinical response
2. To monitor the adherence to drugs
3. Suspected toxicity

Question 14

What are the co morbidities that would indicate TDM in patients

Answer 14

1. Drug- drug interactions
2. Renal and hepatic disease
3. GIT issues that could result in decreased absorption

Question 15

What are the possible causes of lower concentrations than what is expected

Answer 15

1. Incorrect dose was given
2. Patient is non adherent
3. Rapid elimination of the drug is present [Induction, genetics, increased renal excretion]
4. Timing of the sample was taken at the incorrect time

Question 16

What are the causes of higher than normal concentration

Answer 16

1. Error in the dose regimen
2. There is a decrease in renal and hepatic function
3. Slowed elimination
4. Timing of the sampling is incorrect

Question 17

When is the steady state achieved

Answer 17

At least 5 half lives after the last dose change

Question 18

What is zero order kinetics

Answer 18

The body eliminates a fixed amount of the drug per unit of time. The elimination is linear irrespective of the conc. of the drug

Question 19

What is first order kinetics

Answer 19

This is where the rate of elimination is proportional to the drug conc..Elimination is exponential on a concentration vs. time graph.

Question 20

What is meant by a Capacity-saturable metabolism

Answer 20

This is where the drug elimination become saturated at higher drug concentrations and so there is a transition from a first order