Ergot derivatives for Parkinsonism.

The response of Parkinsonism to three ergot derivatives which modify dopaminergic transmission was studied. CF 25-397 behaved more as an antagonist than an agonist. Lergotrile was an agonist with therapeutic properties marred by prominent hepatotoxicity. Bromocriptine is an effective anti-Parkinsonian agent, particularly useful in patients with prominent dyskinesia or "on-off" reactions to levodopa; in most patients optimal results have been obtained by combining from 40 to 90 mg of bromocriptine daily with approximately 60% of the previous maximal dose of levodopa. Unfortunately, only some 50% of patients tolerate long-term bromocriptine therapy, but all adverse reactions have been dose dependent and reversible.