PSP: SOME ANSWERS( continued)
What about treatment with medication?
Several prescription medications can help patients with PSP, in some cases. Levodopa and carbidopa are the almost universally prescribed generic form of the brand name Sinemet. Levodopa is the component that helps the disease symptoms; carbidopa simply helps prevent the nausea that levodopa can cause. When levodopa came along in the late 1960s, it was a revolutionary treatment for Parkinson’ s, but it is of only modest benefit in PSP. It can help the slowness, stiffness, and balance problems of PSP to a degree, but usually not the mental, speech, visual, or swallowing difficulties. About 50 % of those with PSP-parkinsonism respond to levodopa / carbidopa, while the figure is only 14 % for Richardson’ s syndrome. The drug typically loses its benefit after two or three years, but a few patients with PSP continue to respond.
Some patients with PSP require large dosages to see an improvement— up to 1,200 milligrams of levodopa( with carbidopa) per day— so the dosage should generally be raised to at least that level under the close supervision of a physician, unless a benefit or intolerable side effects occur sooner. The most common side effects of this drug in PSP are confusion, hallucinations, and dizziness. These typically disappear after the drug is stopped. The most common side effect in patients with Parkinson’ s disease, involuntary writhing movements( chorea or dyskinesias), occur very rarely in PSP, even at high dosages.
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Patients with PSP should generally receive the standard Sinemet or generic carbidopa / levodopa preparation rather than the controlled-release( Sinemet CR or generic carbidopa / levodopa ER) form. The CR or ER form is absorbed from the intestine into the blood slowly and can be useful for people with Parkinson’ s disease who respond well to carbidopa / levodopa but need to prolong the number of hours of benefit from each dose. In PSP, however, such response fluctuations almost never occur. Because the CR or ER is sometimes absorbed very little or erratically, a poor response in a patient with PSP might be incorrectly blamed on the fact that the disease is usually unresponsive to the drug. Such a patient might actually respond to the standard form, which reaches the brain in a more predictable way.
For people with PSP who cannot swallow pills safely, a solution is to crush a regular levodopa-carbidopa tablet into a food or beverage that is easily swallowed. The drug dissolves best in acidic beverages such as juices or sodas.
Another formulation of levodopa-carbidopa combines those two drugs with a third drug, entacapone, in the same tablet called Stalevo. The entacapone slows the rate at which dopamine is broken down. It is useful for patients with Parkinson’ s but rarely, if ever, in PSP.
There are three dopamine receptor agonists drugs on the market for Parkinson’ s— Mirapex( pramipexole), Requip( ropinirole), and Neupro( rotigotine, which comes only as a skin patch). For PSP, these rarely give any benefit beyond that provided by carbidopa / levodopa and may cause hallucinations and confusion, excessive involuntary movements, dizziness, and nausea.
Antidepressants have also had some modest success in PSP, sometimes relieving the depression that can be part of the disease. There are many antidepressants and none has been shown to be superior to any others. The older, tricyclic antidepressants seem to be no less effective in PSP than the newer reuptake blocker antidepressants.