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On/off phenomena

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

This phenomenon consists of a sudden loss of anti-Parkinsonian effects of L-dopa and a resulting hypokinesia and rigidity. The loss of effectiveness of L-dopa therapy may last for several hours and can occur irregularly throughout the day.

It is a troublesome symptom which usually develops some time after the patient has been on L-dopa. It is not related to blood levels of L-dopa.

Consider:

  • increasing the frequency and decreasing drug dosage.
  • a drug holiday
  • anticholinergic drugs
  • apomorphine by injection

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