off time

In Parkinson's disease, the hours of the day when a dose of medicine has worn off and the slowness, stiffness or other symptoms return, usually between doses.

Levodopa, the main treatment for Parkinson's disease, works in doses, and early on each dose carries a person comfortably to the next. Over the years that changes. The National Institute of Neurological Disorders and Stroke says that medicines may work for shorter periods as time passes and that their effects become less predictable. The result is a day divided into on time, when the medicine is working and movement is good, and off time, when it has worn off and the symptoms come back.

Trials of Parkinson's drugs measure both. The TEMPO-3 trial report in JAMA Neurology defines off time as the return or worsening of motor and non-motor symptoms often experienced between medication doses, and on time as good mobility, smoother movement and fewer symptoms. The trial's main measure was good on-time, which is on time without troublesome dyskinesia, the involuntary movements the medicines can cause, because an hour of movement spoiled by writhing is not an hour gained. Participants in that trial began with 5.5 hours of off time in a typical day.

Sources