Initial therapy for Parkinson's disease: levodopa vs. dopamine receptor agonists

Abstract

Levodopa therapy is essential for patients in the advanced stages of Parkinson's disease. However, at early stages, DA agonist therapy has similar efficacy in the treatment of parkinsonism and a lower incidence of motor complications compared to levodopa therapy several years after the initiation of the therapy. The main factors causing motor complications have been speculated to be a severe reduction of dopaminergic nerve terminals because of disease progression, and a pulsatile stimulation of DA receptors using a drug with a short plasma half-life. DA agonists have longer plasma half-lifes than levodopa; therefore, they are expected to have a favorable effect on motor complications. Moreover, two clinical reports confirmed the potential neuroprotection by DA agonists. Although the patient's conditions should be considered in the selsction of a drug, DA agonist therapy is recommended as the initial therapy for Parkinson's disease.

Consensus guideline for the diagnosis and treatment of tetrahydrobiopterin (BH4) deficiencies

“…Non-ergot DAs (apomorphine, piribedil, pramipexole, ropinirole and rotigotine) seem to possess a very low and statistically insignificant risk of fibrotic complications and are preferred in clinical practice [131]. Potential benefits of DAs are related to their longer bioavailability in the synaptic cleft leading to equalised L-Dopa/DC inhibitor stimulation of dopaminergic terminals in the striatum [132].…”

Higher nigrostriatal dopamine neuron loss in early than late onset Parkinson's disease?—A [99mTc]‐TRODAT‐1 SPECT study

“…This difference cannot be attributed to medication, since it is not necessary to withdraw PD medication to measure DAT levels with SPECT 13. Moreover, previous reports have suggested that dopaminergical agonist therapy14 that are more commonly used in EOPD might reduce DAT loss during PD disease progression. Although EOPD patients had lower DAT density, they presented similar motors symptoms disability and PD severity at off state.…”

Different Alterations of Cerebral Regional Homogeneity in Early-Onset and Late-Onset Parkinson's Disease

“…With respect to treatment, EOPD patients have a better medication response to levodopa (Ribeiro et al, 2009 ). Moreover, Kondo et al have suggested that the dopamine agonist therapies that are more commonly used in EOPD might reduce dopamine transporter (DAT) loss during PD disease progression (Kondo, 2002 ). The pathophysiological mechanisms that differentiate EOPD and LOPD disease progression are not yet clear (Shih et al, 2007 ).…”