Drugs used in Parkinsonism & other movement disorders

Question 1

MOA of levodopa +/- carbidopa

Answer 1

Precursor of dopamine

Carbidopa inhibits peripheral metabolism via dopa decarboxylase

Question 2

Which types of drugs diminish doses and prolong the actions of levodopa?

Answer 2

COMT inhibitors

MAO B inhibitors

Question 3

Adverse effects of levodopa

Answer 3

GI upset (emesis)
Dyskinesias in 80% - usually choreoathetosis of the face and distal extremities
Postural hypotension

Question 4

COMT inhibitors used in the treatment of Parkinson’s disease

Answer 4

Tolcapone

Entacapone (peripheral action only)

Question 5

MAO-B inhibitors used in the treatment of Parkinson’s disease

Answer 5

Selegiline, rasagiline

*NB serotonin syndrome with meperidine and possibly SSRIs and TCAs

Question 6

D2 agonists used in the treatment of PD

Answer 6

Bromocriptine (ergot; not frequently used anymore)
Ropinirole - can be used as sole agent in early PD and adjunct to L-dopa. Non-ergot
Apomorphine

Question 7

D3 agonist used in the treatment of PD

Answer 7

Pramipexole; can be used as sole agent in early PD and adjunct to L-dopa

Question 8

Injected subcutaneously to provide rapid but temporary relief of “off-periods” of akinesia in patients on optimized dopaminergic therapy

Answer 8

Apomorphine

Question 9

Common side effects of dopamine agonists

Answer 9

Anorexia, nausea, constipation, postural hypotension, dyskinesias, and mental disturbances (confusion, delusions, and hallucinations)
*NB: mental disturbances occur more frequently with DA receptor activators than with levodopa.

Question 10

Antimuscarinic agent used in treatment of PD

Answer 10

Benztropine

Question 11

What symptoms of PD do antimuscarinic agents improve?

Answer 11

Tremor and rigidity but NOT bradykinesia

Question 12

D2 antagonists used in the treatment of HD

Answer 12

Haloperidol

Perphenazine

Question 13

Amine-depleting drugs used in the treatment of HD

Answer 13

Reserpine

Tetrabenazine

Question 14

Side effects of haloperidol

Answer 14

Extrapyramidal dysfunction

Question 15

Side effects of tetrabenazine

Answer 15

depression, hypotension, sedation

Question 16

Drugs for Tourette’s syndrome

Answer 16

Haloperidol
Clonidine
- Reduce vocal and motor tic frequency and severity

Question 17

Drugs for managing essential tremor

Answer 17

Beta blockers: propranolol, metoprolol

Question 18

What drug is most suitable for management of tremor in a patient who has pulmonary disease?

Answer 18

Metoprolol: it is B1 selective and is equally effective.

Question 19

D2 agonist that is metabolized by hepatic CYP1A2, and therefore whose plasma levels may be increased by other substrates of this enzyme (including caffeine and warfarin)

Answer 19

Ropinirole

Question 20

Antiviral used in the treatment of PD

Answer 20

Amantadine

Question 21

MOA of amantadine

Answer 21

exact mechanism is unknown; increases the neurotransmission of DA, either by increasing synthesis or release of DA or inhibition of DA reuptake

Question 22

Drugs that can induce parkinsonism

Answer 22

1. Butyrophenone and phenothiazine are the most important antipsychotics that cause PD
2. Reserpine
3. MPTP ( a by-product of the attempted synthesis of an illicit meperidine analog, which causes irreversible parkinsonism through destruction of dopaminergic neurons in the nigrostriatal tract)