Parkinsons Drugs

Question 1

In parkinsons disease the pars compacta part of the substantia nigra becomes smaller and eventually reduces or stops producing dopamine. What can this cause in patients?

Answer 1

• direct pathway of basal ganglia is affected

- patients struggle to initiate movement due to low dopamine levels

Question 2

Ropinirole, is a medication used to treat Parkinson’s disease and restless legs syndrome. What is the aim of this drug?

Answer 2

• to increase dopamine levels

Question 3

Ropinirole, is a medication used to treat Parkinson’s disease and restless legs syndrome by increasing the levels of dopamine. Is it generally used early on in Parkinsons disease or later in the disease?

Answer 3

• earlier

- there are more dopaminergic receptors to act on

Question 4

Ropinirole, is a medication used to treat Parkinson’s disease and restless legs syndrome by increasing the levels of dopamine. What is the mechanism of action of Ropinirole?

Answer 4

• selectively stimulate dopamine D2 receptors on the post-synapse
• in the basal ganglia direct pathway

Question 5

Levodopa, also known as L-DOPA is a prodrug of dopamine that is administered to patients with Parkinson’s due to its ability to cross the blood-brain barrier. What does it mean to be a pro-drug?

Answer 5

• levodopa, also known as L-DOPA only becomes active when it is metabolised
• eventually becomes dopamine

Question 6

Levodopa, also known as L-DOPA is a prodrug of dopamine that is administered to patients with Parkinson’s due to its ability to cross the blood-brain barrier. It is a pro-drug because it only becomes active once it is metabolised, and then become dopamine. How does Levodopa become dopamine?

Answer 6

• Levodopa (L-DOPA) crosses the BBB
• Levodopa (L-DOPA) converted by DOPA decarboxylase into dopamine
• dopamine stimulates the basal ganglia direct pathway

Question 7

Levodopa, also known as L-DOPA is a prodrug of dopamine that is administered to patients with Parkinson’s due to its ability to cross the blood-brain barrier. There is an enzyme that is able to convert L-DOPA into dopamine. What is this enzyme called?

Answer 7

• DOPA decarboxylase

- present throughout the body

Question 8

Levodopa, also known as L-DOPA is a prodrug of dopamine that is administered to patients with Parkinson’s due to its ability to cross the blood-brain barrier. There is an enzyme that is able to convert L-DOPA into dopamine called DOPA decarboxylase that is present throughout the body. Why is it bad if this enzyme converts L-DOPA into dopamine outside the brain?

Answer 8

• dopamine will not reach the direct basal ganglia pathway

Question 9

Rasagiline is an irreversible inhibitor of something that can be used to treat Parkinsons disease. What is this drug able to inhibit that increases dopamine levels?

Answer 9

• monoamine oxidase (MAO)-B
• MAO-B degrades dopamine in astrocytes or pre-synapse as it is part of mitochondrial membranes
• inhibition of MAO-B means higher levels of dopamine

Question 10

Entacapone is a selective reversible catechol-O-methyltransferase (COMT) inhibitor for the treatment of Parkinson’s disease. What does this drug do?

Answer 10

• COMT break down dopamine after it has been reabsorbed at pre-synapse
• inhibition of COMT means there will be more dopamine

Question 11

Carbidopa is a drug given to people with Parkinson’s disease in order to inhibit what enzyme that is responsible for the break down of L-DOPA?

Answer 11

• dopa decarboxylase