Drugs For Parkinson's Disease

Question 1

Dopamine agonist

Answer 1

Moa:stimulate dopamine receptors, inhibit prolactin secretion, reduce size of prolactinomas, decrease GH concentration in ppl with acromegaly

Precaution
Compromised cerebral or cardiac circulation -risk of hypotension and collapse.
Treatment with dopamine antagonist such as metoclopramide - avoid combined use (mutual antagonism)

Adr: common more than 1%
Nausea,vomiting, constipation, headache, dizziness, orthostatic hypotension,nasal congestion, peripheral edema,digital vasospasm..pg 753 AMH

Psy effects
Impulse control disorders
Withdrawal syndrome

Question 2

Apomorphine

Answer 2

Indication:PD in ppl severely disabled by motor fluctuations refractory to conventional treatment

Precaution
Allergy to morphine or it’s derivatives
Respiratory or CNS depression
Hypotonia
Neuropsychiatric disorder -alzheimers
Ppl whose ‘on’ response to levodopa is marred by severe dyskinesia -risk of aggravation
Predisposition to nausea & vomiting
Risk of prolonged QTC intervals
Apomorphine can cause hypotension and used with caution in cardiovascular disease or taking vasoactive drugs

Elderly: use with caution; risk of respi depression & orthostatic hypotension

Preg: avoid use

Bf: contact preg information centre

Adr common more than 1%: eosinophilia,injection site reaction including subcutaneous nodules and skin necrosis

Dosage initiation

Domperidone pre treatment 48 to 72 hours before apomorphine dose. Hold all anti Parkinsonian drugs overnight to provoke and off period in motor performance. Dosing usually less than 15 mins, 1.5 to 7mg

Maintenance: continuous infusion of 2-4mg/hr

Practice points

Apomorphine injection are useful for off periods of the day
. techniques requires dexterity BD requires a carer to administer
If spilt, apomorphine may permanently stain clothing and most surfaces green

Question 3

Bromocriptine

Answer 3

Indication: PD, acromegaly where surgery or radiotherapy is CI or has failed to control disease or until radiotherapy becomes fully effective
Hyperprolactonemia including prolactinomas

Precaution

Respiratory, pericardial or retroperitoneal fibrotic disorder - increase risk of fibrotic disorders

Tx with ergometrine, vasoconstrictive sympathomimetics- possible cvs AE risk

Peptic ulcer-risk of gastric hemmorhage in ppl with acromegaly