7- Renal excretion of Drugs

Question 1

What happens when a drug is bound to plasma proteins

Answer 1

It cannot be filtered and removed by the kidney as effectively- which can extend the duration of action

Question 2

What is the main aim during drug metabolism

Answer 2

Transformation of a drug into a form that is readily excreted by modification of its molecular properties to a more water-soluble species

Question 3

How can we tell drugs and metabolites are excreted in urine

Answer 3

At macro level- colour, smell

At macro level- analytical spectroscopy/spectrometry

Question 4

What does biotransofrmation do

Answer 4

Increase hydrophilic character to render metabolites water soluble which aids urinary excretion

Question 5

What are some examples of polar (hydrophilic groups)

Answer 5

OH NH2. COOH

Question 6

What are factors affecting renal excretion

Answer 6

Plasma protein binding
Age
Renal Function
Blood flow

Question 7

What does LogD show in terms of metabolism

Answer 7

If logD is positive it indicates that the drug will favour distribution into the lipid layer and will therefore be reabsorbed into the blood stream- reduces excretion.

opposite for low logD

Question 8

What are determinants for rate of drug filtration

Answer 8

Size restriction and protein binding.