Anticholinergics and dyskinesia

Pathophysiology of L-dopa-induced motor and non-motor complications in Parkinson's disease

Involuntary movements, or dyskinesia, represent a debilitating complication of levodopa (L-dopa) therapy for Parkinson's disease (PD). L-dopa-induced dyskinesia (LID) are ultimately experienced by the vast majority of patients. In addition, psychiatric conditions often manifested as compulsive behaviours, are emerging as a serious problem in the management of L-dopa therapy. The present review attempts to provide an overview of our current understanding of dyskinesia and other L-dopa-induced dysfunctions, a field that dramatically evolved in the past twenty years. In view of the extensive literature on LID, there appeared a critical need to re-frame the concepts, to highlight the most suitable models, to review the central nervous system (CNS) circuitry that may be involved, and to propose a pathophysiological framework was timely and necessary. An updated review to clarify our understanding of LID and other L-dopa-related side effects was therefore timely and necessary. This review should help in the development of novel therapeutic strategies aimed at preventing the generation of dyskinetic symptoms.

Striatal cholinergic interneuron regulation and circuit effects

The striatum plays a central role in motor control and motor learning. Appropriate responses to environmental stimuli, including pursuit of reward or avoidance of aversive experience all require functional striatal circuits. These pathways integrate synaptic inputs from limbic and cortical regions including sensory, motor and motivational information to ultimately connect intention to action. Although many neurotransmitters participate in striatal circuitry, one critically important player is acetylcholine (ACh). Relative to other brain areas, the striatum contains exceptionally high levels of ACh, the enzymes that catalyze its synthesis and breakdown, as well as both nicotinic and muscarinic receptor types that mediate its postsynaptic effects. The principal source of striatal ACh is the cholinergic interneuron (ChI), which comprises only about 1-2% of all striatal cells yet sends dense arbors of projections throughout the striatum. This review summarizes recent advances in our understanding of the factors affecting the excitability of these neurons through acute effects and long term changes in their synaptic inputs. In addition, we discuss the physiological effects of ACh in the striatum, and how changes in ACh levels may contribute to disease states during striatal dysfunction.

Amisulpride versus moclobemide in treatment of clozapine-induced hypersalivation

OBJECTIVES

Previous publications demonstrated substitute benzamides as effective agents in treatment of clozapine-induced sialorrhea (CIS). The aim of this study was to compare efficacy of amisulpride and moclobemide (both from the substitute benzamide group) in controlling, or at least minimizing, CIS.

METHODS

The study was designed as a 6-week, two-center, fixed-dose, comparison study of 400 mg/day of amisulpride versus 300 mg/day of moclobemide as an adjunctive treatment in 53 schizophrenia and schizoaffective disorder patients (diagnosed according to DSM-IV) suffering from CIS. The patients were treated with each medication during 2 weeks, followed by a washout period of 2 weeks. Primary outcome measures included the reduction in the five-point Nocturnal Hypersalivation Rating Scale (NHRS). Secondary outcomes included the Positive and Negative Syndrome Scale (PANSS), Manic State Assessment Scale, and Extrapyramidal Symptom Rating Scale (ESRS).

RESULTS

Both amisulpride and moclobemide were very effective in reducing CIS. Almost 74% of patients treated with amisulpride and 83% of patients treated with moclobemide showed some level of improvement on NHRS. Only in one patient treated with amisulpride, CIS worsened.

CONCLUSIONS

Both medications were safe and effective as treatment of CIS. Although moclobemide exceeded amisulpride in antisalivation activity, treatment of CIS with amisulpride leads to improvement in psychotic symptoms.

Motor complications in Parkinson disease: Clinical manifestations and management

Long-term dopaminomimetic therapy, not limited to levodopa, is complicated by the emergence of variations of motor response in a majority of Parkinson disease (PD) patients. These variations can occur in different forms, as early wearing off during the initial stage of motor complications, dyskinesias in the intermediate stage, and complex fluctuations in the advanced stage. Considered to be a major source of disability in advanced PD patients, recognition of these complications is critical in order to develop different strategies designed not only to treat these problems when they develop, but also to prevent troublesome complications associated with potential risk factors. In this article, authors classify a wide clinical spectrum of motor complications into different stages as the disease progresses through the treatment. A number of strategies are proposed in order to manage these complications as well as to avoid them. Better understanding of these potential complications will result in better management of these problems and lessen the disability associated with advanced PD.