Bromocriptine and the clinical spectrum of Parkinson's disease.

As the direct agonist with the widest clinical use, bromocriptine provides a unique window into the clinical spectrum of Parkinson's disease. The efficacy of bromocriptine for therapy of de novo Parkinson's disease has recently been confirmed using a double-blind design with L-Dopa (Sinemet). Over a period of 5.5 months, bromocriptine was found to be as effective as L-Dopa in reducing the functional and neurological disability of Parkinson's disease. This study complements others and demonstrates a role for bromocriptine as de novo therapy. A longitudinal study comparing bromocriptine with L-Dopa is underway, but previous observations with bromocriptine suggest modest, transient beneficial effects with significantly less fluctuation of disability and less dyskinesia when used alone or in combination with L-Dopa. The transient benefits of bromocriptine on progressive disability suggest that both pre- and post-synaptic defects are eventually involved in Parkinson's disease. While agonists with improved efficacy and minimal side effects are required for symptomatic treatment of Parkinson's disease, strategies to protect pre- and post-synaptic neuron populations against progressive dysfunction must be developed.