Dopamine agonist treatment of fluctuating parkinsonism. D-2 (controlled-release MK-458) vs combined D-1 and D-2 (pergolide)
J. E. Ahlskog, M. D. Muenter, P. A. Bailey and P. M. Stevens
Department of Neurology, Mayo Clinic, Rochester, MN 55905.
Adjunctive treatment with the very potent and selective dopamine D-2
agonist MK-458 (controlled-release formulation) improved the control of
parkinsonism in patients with fluctuating responses to levodopa therapy
(with carbidopa). We subsequently switched patients to adjunctive treatment
with pergolide, a less potent D-2 agonist. Pergolide therapy controlled
parkinsonism more effectively than controlled-release MK-458. Unlike
MK-458, pergolide mesylate also has D-1 agonist properties, apparently
accounting for its greater antiparkinsonism efficacy. Adjunctive treatment
with controlled-release MK-458 elicited less choreiform dyskinesias than
either pergolide adjunctive therapy or therapy with carbidopa-levodopa
alone; this finding suggests that D-1 receptor stimulation contributes to
the elicitation of medication-induced chorea. The highest doses of
controlled-release MK-458 resulted in paradoxical freezing of gait in
almost one third of patients. This finding suggests that gait freezing,
common in untreated parkinsonism, can also be elicited by excessive D-2
stimulation.
