Anti Parkinsion Drugs Flashcards
Classify anti Parkinson drugs
- Dopamine precursors
- dopamine agonists
- NMDA receptor antagonists
- MAO-B inhibitors
- COMT inhibitors
- centrally acting anticholinergic drugs
- anti-histamines with anticholinergic activity
Name a precursor of dopamine that does not cross the blood brain barrier and act as a pro drug
Levodopa
Which enzyme converts levodopa into dopamine 
Decarboxylase 
Levodopa is used in combination with which drugs
Carbidopa/ Benserazide
Why is levodopa given 30 to 60 minutes before meals
Because amino acids present in the food interfere with absorption of levodopa
What are the metabolites of levodopa
Homovanillic acid (HVA)
3,4- dihydroxyphenylacetic acid (DOPAC)
What are the adverse effects of levodopa
- GIT: nausea, vomiting, anorexia
- CVS: postural hypotension, tachycardia, palpitation and rarely cardiac arrhythmias
- Alteration in taste sensation
- Dyskinesias
- CNS: Mental changes
- Fluctuations in response

What is the ratio of using levodopa with carbidopa / benserazide 
Levodopa : carbidopa / benserazide
4:1
Bromocriptine is contraindicated in which patients
Patient with a history of
1. mental illness
2. recent MI
3. peptic ulcers
4. peripheral vascular disease
Which drug rarely causes fulminant hepatitis and should be avoided in patients with liver disease?
Tolcapone
What are the metabolites of selegiline
amphetamine and methamphetamine
Which anti- Parkinson’s drug is also an antiviral that is used for the treatment and prophylaxis of influenza A
Amantadine
What are the side effects of amantadine
- Headache, heart failure, hypotension, hallucinations, nausea, vomiting, constipation, dry mouth and insomnia
- Livedo reticularis (discoloured patches on the skin)
Which group anti-Parkinson’s causes blurring vision and urinary retention as an adverse effect
Anti cholinergic drugs ( benzhexol [trihexyphenidyl] and benztropine)
Levodopa is not active in drug induced parkinsonism, why?
- Dopamine receptors are blocked
- There is no deficiency of dopamine
What is the advantage of using levodopa with MAO inhibitors
Retards metabolism Of dopamine And increases plasma concentration of dopamine. 
Why should we avoid prescribing levodopa with pyradoxine?
Pyradoxine Promotes conversion of levodopa to dopamine and reduces it’s therapeutic effect
Should levodopa be given with anti-hypertensive agents?
No because it worsens postural hypotension
What happens when levodopa is given with metoclopramide?
It crosses BBB, blocks D2 receptors in the basal ganglia and causes drug induced Parkinsonism
Which drugs can be used to treat Tremors
- Beta blockers
- antiepileptic drugs
- botulinum toxin
Which drugs can be used to treat Tremors
- Beta blockers (Propranolol metoprolol)
- antiepileptic drugs (Gabapentin, primidone, topiramate)
- botulinum toxin
What are the drugs used for the treatment of Huntingtons disease
- Amine depleting drugs (reserpine, tetrabenazine)
- Dopamine receptor antagonists (haloperidol, perphenazine)
- Olanzapine

What drugs are used for the treatment of Tourette’s syndrome
- Dopamine D2 antagonists
- Carbamazepine
- Clonazepam
- Clonidine 
Which drugs are used for the treatment of drug-induced dyskinesis? Why can’t levodopa and bromocriptine be used
- Benztropine Or diphenhydramine
Because dopamine receptors are blocked by antipsychotic drugs
