An anti-parkinson’s medication taken to provide immediate relief from motor symptoms such as severe bradykinesia, rigidity, or freezing when the regular medication regimen cannot control them. Such off-state episodes can occur in the disease’s later stages when conventional anti-Parkinson’s medications are no longer effective in meeting the brain’s dopamine needs.
Extra oral doses of regular release levodopa, as levodopa/carbidopa (Sinemet) or levodopa/benser-azide (Madopar), often can act as rescue drugs, although they can take 45 minutes to an hour to become effective. Extended release formulas such as Sinemet CR, which many people with Parkinson’s take because the effect lasts longer between doses, do not work well as rescue drugs because they are designed to enter the bloodstream slowly over a controlled period.
For extreme symptoms, subcutaneous injection of the drug apomorphine, a potent dopamine agonist medication chemically similar to morphine that is not a narcotic and acts on different receptors in the brain, can provide relief within five to 15 minutes. Other dopamine agonists, because of their receptor activations, tend to be less effective than apomorphine when taken as rescue drugs. The primary drawback of apomorphine is that at present it is available only in injectable form and it almost invariably causes moderate to severe nausea and vomiting in most people. For this reason, rescue drug doses are almost always taken with an antiemetic medication such as trimethobenzamide (Tigan). Also the risk of unde-sired side effects, particularly dyskinesia (fidgety movements) dystonia (extreme muscle rigidity) is quite high when rescue drugs are added to one’s usual dose of medications. It can be a fine balance between relieving one set of symptoms and causing another.