3. OTHER DRUGS - Amantidine , MAO inhibitors and COMT inhibitors

Amantidine is an antiviral used for the treatment of

Influenza A , herpes simplex and varicella zoster

has modest anti parkinsonian activity

Given orally and is well tolerated

MOA of Amantidine as an anti parkinsonian drug

acts by releasing dopamine from intact dopaminergic neurons - increases levels in the synpases

also decreases dopamine reuptake in CNS

Only a few benefits and tolerance develops with time.

ADRS of Amantidine

nightmares

insomnia

Hallucinations

Delirium

dizziness

GIT disturbances

skin discoloration

dry mouth

peripheral edema

rarely - leukopenia

DOPAMINE METABOLISM INHIBITORS

MAOb inhibitors - selegiline , rosagiline

COMT inhibitors - entacapone and tolcapone

dopamine is metabolised by MAO (mono amine oxidase) and COMT (catechol-o-methyl transferase)

Does Entacapone act centrally or peripherally

peripherally

Does Tolcapone act centrally or peripherally

both centrally and peripherally

Entacapone is useful in

end dose of motor flactuations as an adjunct to L dopa - carbidopa combinations.

use of dopamine decarboxylase inhibitors is associated with the rise in 3-o methyldopa

ADRS of entacapone

increased L DOPA associated dyskinesias , nausea and confusion

diarrhea

abdominal pain

orthostatic hypotension

sleep disturbances

orange discolouration in urine.

ADRs of tolcapone

Hepatotoxic effects - hepatotoxicity with cases of acute hepatic failure rarely reported.

SELEGELINE

MAO B inhibitor. In high doses inhibits MAO A.

• Used in conjunction with L-dopa in severe disease to reduce end of dose deterioration.

Early use may delay need for L-dopa therapy and slow down progression of disease.

DOSAGE OF SELEGINE

• Given orally.

• Dose 10MG OD in the morning, or 5mg at breakfast and 5 mg at midday.

ADRS OF SELEGELINE

• Nausea, vomiting

• Hypotension

• Confusion

• Agitation

DIs OF SELEGELINE

• Should not be taken with:

• Meperidine

• TCAs

• Serotonin reuptake inhibitors- may cause acute toxic reaction of serotonin syndrome

• Adverse effects of levodopa may be increased by selegeline.

Rasagiline

• MAO B inhibitor

• Pharmacology like selegeline, but pore potent in preventing MPTP induced Parkinsonism.

Used as a neuroprotective agent and for early treatment.

• Preps - 0.5mg, 1mg

• Dose - standard dose 0.5 mg /d

Other movement disorders

• Tremors

• Chorea

• Huntington's disease

• Ballismus

• Athetosis and dystonia

• Tics

• Drug induced dyskinesias

• Restless leg syndrome

• Wilson's disease