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MK 458, a selective and potent D2 receptor agonist in advanced Parkinson's disease
A Lieberman1, L Chin, G Baumann
1Department of Neurology, N.Y.U. School of Medicine, NY 10016.
Abstract:
MK 458 is a potent and selective D2 receptor agonist. MK 458 consists of (+)-4-propyl-9-hydroxynaphthoxazine (PHNO) in a hydroxypropyl-methylcellulose-lactose matrix. MK 458, mean dose 8.1 mg (range 2.5 to 13.5 mg), was administered to 14 patients with advanced Parkinson's disease (PD) who were no longer satisfactorily responding to levodopa. The duration of the study was 4 weeks with a titration to maximum dose in 2 weeks. The addition of MK 458 resulted in a mean reduction in levodopa of 41% (range 0 to 81%). This degree of levodopa reduction was not seen in previous studies with other DA agonists. While the reduction in signs of PD was comparable to those on levodopa, MK 458 did not induce dyskinesias or dystonias. It is postulated that MK 458 may be able to replace levodopa as the primary treatment for PD.
Insights
MK 458, a D2 receptor agonist, effectively reduced levodopa dosage by 41% in Parkinson's disease patients. This novel treatment showed comparable efficacy without inducing dyskinesias, suggesting potential as a primary therapy.
Area of Science:
- Neuroscience
- Pharmacology
- Neurology
Background:
- Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor symptoms.
- Levodopa is a primary treatment, but its efficacy diminishes over time, and it can cause motor complications.
- Alternative or adjunctive therapies are needed for advanced PD patients with suboptimal levodopa response.
Purpose of the Study:
- To evaluate the efficacy and tolerability of MK 458, a selective D2 receptor agonist, in patients with advanced Parkinson's disease.
- To assess the potential for MK 458 to reduce levodopa dosage.
- To determine if MK 458 can improve PD symptoms without inducing dyskinesias.
Main Methods:
- A 4-week study involving 14 patients with advanced PD receiving levodopa.
- MK 458 (mean dose 8.1 mg) was added and titrated over 2 weeks.
- Levodopa dosage was reduced, and motor symptoms, dyskinesias, and dystonias were assessed.
Main Results:
- MK 458 addition led to a mean 41% reduction in levodopa dosage.
- The reduction in levodopa was greater than observed with other dopamine agonists in previous studies.
- Motor symptom improvement was comparable to levodopa, but MK 458 did not induce dyskinesias or dystonias.
Conclusions:
- MK 458 is a potent D2 receptor agonist with significant potential in Parkinson's disease management.
- It effectively reduces levodopa requirements and improves motor symptoms without causing troublesome dyskinesias.
- MK 458 may represent a viable alternative to levodopa as a primary treatment for PD.