Dopamine agonists in Parkinson’s disease

Bonucelli U, Comparing dopamine agonists in Parkinson s disease, Current Opinion Neurology 16 513—S19, 2003. 

Stocchi F, Dopamine agonists in Parkinson s disease—What is their role in early treatment CNS Drugs 10 159—170, 1998. 

Tintner R, Jankovic J. Dopamine agonists in Parkinson s disease. Expert Opin Investig Drugs. 2003 12 1803-1820. 

Pineau F, Schtipbach M, Corvol JC, Fla-mand-Rouviere C, Vidailhet M, Roze E. Long-standing paraphilia induced by dopamine agonists in Parkinson s disease. Mov Disord 2010 25(7) 963-5. 

Bromocriptine is a dopamine agonist acting by direct stimulation of the dopamine receptors. In Parkinson s disease, it is reserved for use in patients who are intolerant to levodopa or in whom levodopa alone is not sufficient. Orphenadrine is an antimuscarinic indicated in Parkinson s disease. Antimuscarinics tend to be more effective than levodopa in targeting tremor rather than rigidity and bradykinesia. Moclobemide is an antidepressant referred to as a reversible monoamine oxidase inhibitor (RIAAA) type A. 

Thobois S (2006) Proposed Dose Equivalence for Rapid Switch Between Dopamine Receptor Agonists in Parkinson s Disease a Review of the Literature. Clin Ther 28 1... 

Figure 7.8 Dopamine and motor function. When nigrostriatal dopamine activity is normal so is motor function. Any reduction in this DA activity, as in Parkinson s disease, results in reduced motor activity, i.e. akinesia. By contrast, too much DA activity, as in Huntington s Chorea, produces abnormal motor function, i.e. dyskinesia. The latter may be controlled by neuroleptic drugs (DA antagonists) but they can swing the balance in DA activity sufficiently to produce akinesia (Parkinsonism). DA agonists (and levodopa) may overcome akinesia but can induce DA overactivity and dyskinesia (peak dose effect) (see Chapter 15)...

Roth T., Rye D Borchert L. et al. (2003). Assessment of sleepiness and unintended sleep in Parkinson s disease patients taking dopamine agonists. Sleep Med. 4, 275-80. 

E.-K. Tan (2003). Dopamine agonists and their role in Parkinson s disease treatment. Exp. Rev. Neurotherap. 3 805-810. 

Dopamine agonists suppress prolactin release very effectively in patients with hyperprolactinemia. GH release is reduced in patients with acromegaly, although not as effectively. Cabergoline and bromocriptine are also used in Parkinson s disease to improve motor function and reduce levodopa requirements (see Chapter 28). Newer, nonergot D2 agonists... 

Jenner P. Dopamine agonists, receptor selectivity and dyskinesia induction in Parkinson s disease. Curr Opin Neurol. 2003 16(suppl 1) S3-S7. 

Dopamine receptor agonists are also available for therapy in Parkinson s disease. The strategy of using dopamine agonists early as monotherapy or in combination with levodopa to delay long-term levodopa complications is gaining wider acceptance. 

Driver-Dunkley E, Samanta J, Stacy M. Pathological gambling associated with dopamine agonist therapy in Parkinson s disease. Neurology 2003 61 422-3. 

Apomorphine, a very potent non-selective dopamine agonist, which acts on both Di and D2 receptors, has been nsed with some snccess in Parkinson s disease, particn-larly in patients with severe long-term adverse effects of levodopa. Because of first-pass metabohsm it has to be used subcutaneously, sublingually, or intranasally. Its adverse effects resemble those of levodopa. 

Cantor CR, Stern MB. Dopamine agonists and sleep in Parkinson s disease. Neurology 2002 58(4 Suppl l) S71-8. 

The dopamine D /D2 receptor agonist R-(-)-apomorphine has proven to be very effective in Parkinson s disease. Subcutaneously administered R-(-)-apomorphine in combination with L-DOPA rapidly and consistently reverses the off period motor deficits.253 256 Beside its action as a dopamine D,/D2 receptor agonist, R-(-)-apomorphine can also act as a radical scavenger257 and, therefore, may have neuroprotective properties. One of the major limitations of the clinical use of R-(-)-apomorphine, a catechol-aporphine, however, is its low oral activity. 

Olanow, C.W. Jenner, P. Brooks, D. (1998) Dopamine agonists and neuroprotection in Parkinson s disease. Ann. Neurol 44, SI67-74. 

Parkinson s disease is caused by the oxidative stress-induced loss of dopaminergic neurons and can be effectively treated with levo-dopa in combination with dopa decarboxylase inhibitors such as carbidopa or catechoi-0-methyltransferase inhibitors such as tolca-pone. Levodopa is well known to increase the life spans of patients with Parkinson s disease. It may do this by enhancing brain dopamine levels and inhibiting tyrosine hydroxylase, which produces oxygen radicals. Several dopamine receptor agonists are available for use in Parkinson s disease and are extensively used in patients suffering from the adverse effects of levodopa. Anticholinergics such as trihexyphenidyl are also used in Parkinson s disease. 

Dopamine receptor agonists should not be used in Parkinson s disease prior to a trial of levodopa... 

Dopamine receptor agonist used in Parkinson s disease less toxicity than bromocriptine. Tox dyskinesias, sedation. Piamipexole is similar. 

The combined use of levodopa and dopamine agonists can increase efficacy and adverse effects in Parkinson s disease, therefore doses of both drugs should be slowly adjusted to optimise therapy. A study suggests that bromocriptine can moder-... 

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