at the WPC in washington DC in Feb, one of the speakers referred to coffee as a cheap adenosine A(2A) receptor antagonist. Istradefylline, an adenosine A(2A) receptor antagonist continues to be studied in PD patients--a Phase 3 trial was begun in March 05, referred to as "long term, multicenter study" ; a recent report on another phase 3 study on this drug can be found at:

http://tinyurl.com/jdyhd

meanwhile:
Caffeine Aids Levodopa in Some Parkinson's Patients

By David Douglas

NEW YORK (Reuters Health) Sept 29 - Caffeine appears to enhances the bioavailability of levodopa used in treatment of Parkinson's disease, researchers report in the September issue of Neurology.

"Although the study is an evaluation of a single dose of caffeine in a small number of parkinsonian patients, it shows that in certain patients the effect of levodopa may be

enhanced following the intake of caffeine," lead investigator Dr. Dirk Deleu told Reuters Health.

Dr. Deleu of Gamad Medical Corporation, Doha, Qatar and colleagues note that there have been mixed reports of the efficacy of this combination.

To investigate further, the researchers conducted a double-blind crossover study of 12 patients with idiopathic Parkinson's disease.

They received oral caffeine 200 mg or placebo 15 minutes before treatment with a standard tablet of levodopa 250 mg with carbidopa 25 mg. The second session was conducted 48 hours later.

The researchers assessed responses by the speed of alternative finger tapping in the most affected hand, the walking speed and tremor and dyskinesia score.

In particular, although there was significant intersubject variability, the researchers found a non-significant 39% increase in the magnitude of tapping. This and other responses continued to increase over the 3-hour testing period.

The findings, say the investigators, suggest that caffeine may play a role in dopamine receptor-mediator interactions. These and other results, they add, suggest that more selective adenosine antagonists may be of benefit as synergistc adjuncts to conventional antiparkinsonian agents.

Neurology 2006;67:897-899.