Workshop IV: drug treatment guidelines for the long-term management of Parkinson's disease

Inhibitors of MAO-A and MAO-B in Psychiatry and Neurology

Inhibitors of MAO-A and MAO-B are in clinical use for the treatment of psychiatric and neurological disorders respectively. Elucidation of the molecular structure of the active sites of the enzymes has enabled a precise determination of the way in which substrates and inhibitor molecules are metabolized, or inhibit metabolism of substrates, respectively. Despite the knowledge of the strong antidepressant efficacy of irreversible MAO inhibitors, their clinical use has been limited by their side effect of potentiation of the cardiovascular effects of dietary amines (“cheese effect”). A number of reversible MAO-A inhibitors which are devoid of cheese effect have been described in the literature, but only one, moclobemide, is currently in clinical use. The irreversible inhibitors of MAO-B, selegiline and rasagiline, are used clinically in treatment of Parkinson's disease, and a recently introduced reversible MAO-B inhibitor, safinamide, has also been found efficacious. Modification of the pharmacokinetic characteristics of selegiline by transdermal administration has led to the development of a new drug form for treatment of depression. The clinical potential of MAO inhibitors together with detailed knowledge of the enzyme's binding site structure should lead to future developments with these drugs.

Neuroprotection in Parkinson's disease; a commentary

Parkinson's disease (PD) is a worldwide neurodegenerative disorder. Although the etiology has been linked to genetic and environmental factors, curative treatment remains a challenge. Several hypotheses support different pathophysiological mechanisms related to oxidative stress, glutamate-mediated neurotoxicity, mitochondrial energetic impairment and nitric oxide (NO) over-production. Moreover, apoptotic mechanisms have been identified in PD. In this way, classical drugs such as amantadine, selegiline and dopamine agonists show only a modest neuroprotective effect. New strategies with enormous potential are now under development. These include neuroprotectants and agents that might rescue dopaminergic neurons. Glutamate receptor antagonists, neurotrophins, neuroimmunophilins, adenosine A2A receptor antagonists, iron-chelators and NO modulators, as well as caspase inhibitors have evident neuroprotective properties in experimental PD models.