Introduction to Pharmacology: Pharmacodynamics

Question 0

Define pharmacodynamics.

Answer 0

The study of what drugs do to the body.

Question 1

Define pharmacokinetics.

Answer 1

The study of what the body does to drugs.

Question 2

What is a drug?

Answer 2

A substance that brings about a change in biological function through its chemical actions.

Question 3

What are the 3 types of names a drug is given?

Answer 3

1. Chemical; 2. Generic; 3. Brand

Question 4

In general, what is the function of receptors?

Answer 4

To translate the chemical actions of a drug into a physiological effect.

Question 5

What are the 4 general classifications of receptors?

Answer 5

1. Ion Channel; 2. G-Protein Coupled; 3. Enzyme Coupled Receptors; 4. Intracellular

Question 6

Describe how an ion channel works.

Answer 6

Ion channels are the fastest type of channels, with receptors on or adjacent to the channel. A ligand binds to the receptor, opening the channel, allowing ions to flow across the membrane, changing the polarity of the cell, which leads to other effects.

Question 7

What type of ligands are common to ion channels?

Answer 7

Ligands are commonly neurotransmitters, such as acetylcholine and GABA.

Question 8

Describe how G-protein coupled receptors function.

Answer 8

These are the most common receptors. An agonist binds to the receptor, which activates the coupled G-protein. The G-protein is intracellular, and activates second messengers of a signal transduction pathway (cAMP pathway).

Question 9

What are second messengers?

Answer 9

Signalling molecules that relay the message from the first messenger (the drug binding to a channel) to effectors in the cytoplasm.

Question 10

What are ligands common to G-protein coupled receptors?

Answer 10

Adrenergic agents, such as epinephrine.

Question 11

Describe the functioning of receptors coupled to enzymes (tyrosine kinases).

Answer 11

After ligands binds, the receptors dimerize, activating the tyrosine kinase domain. The activated domain phosphorylates tyrosine residues on various signalling proteins, which then may exert their biochemical effect.

Question 12

What ligands are common to tyrosine kinases?

Answer 12

Generally growth factors, as well as insulin.

Question 13

Describe how intracellular receptors function.

Answer 13

These are the slowest to exert their effects. Receptors are located in the cytoplasm or on the nucleus (where it is brought by a chaperone). Receptors are often transcription factors that play a role in gene expression.

Question 14

What kind of ligands bind intracellular receptors?

Answer 14

Ligands include steroid hormones.

Question 15

What is an agonist?

Answer 15

A substance that has both affinity and intrinsic activity at a receptor. It can be either endogenous or exogenous.

Question 16

What is an antagonist?

Answer 16

A substance that has affinity, but lacks intrinsic activity at a receptor. They are often referred to as inhibitors or blockers.

Question 17

What are the types of antagonists?

Answer 17

Reversible and irreversible.

Question 18

Describe reversible antagonists.

Answer 18

These bind to receptors in a reversible fashion. Increasing levels of the agonist can “outcompete” the reversible antagonist to overcome its effects.

Question 19

Describe irreversible antagonists.

Answer 19

These bind to the receptor irreversibly, where increasing the levels of an agonist will not overcome its effect. They are often referred to as non-competitive.

Question 20

What is a partial agonist?

Answer 20

A substance that has affinity, but less than full intrinsic activity at a given receptor.

Question 21

What is an inverse agonist?

Answer 21

Inverse agonists bind to constitutively active receptors and inactivate them.

Question 22

How is an inverse agonist different from an antagonist?

Answer 22

Unlike antagonists, an inverse agonist does not have to have an agonist present to exert an effect.