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Brian, there might be some significant pharmacokinetic and effectiveness differences among the agonists - the dopamine sites to which the agonist is active - as well as the half-life or duration of effectiveness. tolcapone is not an agonist as I understand. it's function (and that of entacapone) is to retard the COMT (catechol O-methyl transferase) enzyme action which metabolizes levodopa. The effect-result is that the levodopa concentration reaches a higher peak and endures much longer. Bromocriptine has both presynaptic and postsynaptic effects and stimulates D2 receptors. Pergolide does not have presynaptic effects and stimulates both D1 and D2 receptors. Unlike the currently available dopamine agonists, pramipexole and ropinirole are non-ergot derivatives and do not cause skin inflammation, paresthesias, pulmonary infiltrates, or pleural effusion. The COMT inhibitors, tolcapone and entacapone, improve the pharmacokinetics of levodopa by preventing its peripheral catabolism and increasing the concentration of brain dopamine; thus, these agents may reduce the incidence of "wearing-off" effects associated with the short half-life of levodopa and the progression of Parkinson's disease. I agree with you that we would benefit from gathering all the available information on these drugs (actually all that we use) into as concise yet complete a database or 'expert program' that is possible. the drug companies do not wish to assist toward this end - nor do the physicians. yet, the pharmacists and physicians should have the best artificial intelligence programs to provide best diagnosis and prescribing. the patient with access could be nearly able to optimize medication himself if he learns to use such an expert.Few would learn to use it well, but there is some hazard in having some 'fools' per the 'he who acts as his own physician has a fool for a doctor'. I hope this is relevant to your posting. it deserves some discussion at least imo -- Ron Vetter 1936, 1984 PD dz 'paradise is where you make it, not a place to go' e-mail: [log in to unmask] janet paterson http://www.ridgecrest.ca.us/~rfvetter