The effects of entacapone on cardiorespiratory, autonomic, and clinical responses in L-dopa-treated patients with Parkinson's disease

Rest tremor, rigidity, and slowness of movements-considered to be mainly due to markedly reduced levels of dopamine (DA) in the basal ganglia-are characteristic motor symptoms of Parkinson's disease (PD). Although there is yet no cure for this illness, several drugs can alleviate the motor symptoms. Among these symptomatic therapies, L-dopa is the most effective. As a precursor to DA, it is able to replace the loss of DA in the basal ganglia. In the long run L-dopa has, however, disadvantages. Motor response complications, such as shortening of the duration of drug effect ("wearing-off"), develop in many patients. In addition, extensive peripheral metabolism of L-dopa by aromatic amino acid decarboxylase and catechol-O-methyltransferase (COMT) results in its short half-life, low bioavailability, and reduced efficacy. Entacapone, a nitrocatechol-structured compound, is a highly selective, reversible, and orally active inhibitor of COMT. It increases the bioavailability of L-dopa by reducing its peripheral elimination rate. Entacapone extends the duration of clinical response to each L-dopa dose in PD patients with wearing-off fluctuations. COMT is important in the metabolism of catecholamines. Its inhibition could, therefore, theoretically lead to adverse cardiovascular reactions, especially in circumstances of enhanced sympathetic activity (physical exercise). PD patients may be particularly vulnerable to such effects due to high prevalence of cardiovascular autonomic dysfunction, and the common use of monoamine oxidase B inhibitor selegiline, another drug with effects on catecholamine metabolism. Both entacapone and selegiline enhance L-dopa's clinical effect. Their co-administration may therefore lead to pharmacodynamic interactions, either beneficial (improved L-dopa efficacy) or harmful (increased dyskinesia). We investigated the effects of repeated dosing (3-5 daily doses for 1-2 weeks) of entacapone 200 mg administered either with or without selegiline (10 mg once daily), on several safety and efficacy parameters in 39 L-dopa-treated patients with mild to moderate PD in three double-blind placebo-controlled, crossover studies. In the first two, the cardiovascular, clinical, and biochemical responses were assessed repeatedly for 6 hours after drug intake, first with L-dopa only (control), and then after a 2 weeks on study drugs (entacapone vs. entacapone plus selegiline in one; entacapone vs. selegiline vs. entacapone plus selegiline in the other). The third study included cardiovascular reflex and spiroergometric exercise testing, first after overnight L-dopa withdrawal (control), and then after 1 week on entacapone plus selegiline as adjuncts to L-dopa. Ambulatory ECG was recorded in two of the studies. Blood pressure, heart rate, ECG, cardiovascular autonomic function, cardiorespiratory exercise responses, and the resting/exercise levels of circulating catecholamines remained unaffected by entacapone, irrespective of selegiline. Entacapone significantly enhanced both L-dopa bioavailability and its clinical response, the latter being more pronounced with the co-administration of selegiline. Dyskinesias were also increased during simultaneous use of both entacapone and selegiline as L-dopa adjuncts. Entacapone had no effect on either work capacity or work efficiency. The drug was well tolerated, both with and without selegiline. Conclusions: the use of entacapone-either alone or combined with selegiline-seems to be hemodynamically safe in L-dopa-treated PD patients, also during maximal physical effort. This is in line with the safety experience from larger phase III studies. Entacapone had no effect on cardiovascular autonomic function. Concomitant administration of entacapone and selegiline may enhance L-dopa's clinical efficacy but may also lead to increased dyskinesia.

Työkykyarviokokous moniammatillisen työryhmän päätöksentekotilanteena : Tutkimus vuorovaikutuksesta ja potilaan osallisuudesta

Work capacity assessment meeting as a decision-making situation of a multi-professional team a study on interaction and patient participation Multi-professional working has become an increasingly popular method of work in social and health care. The introduction of the viewpoints of several professionals is seen as a way to enhance the openness and quality of decision-making. However, so far relatively few study results are available on the implementation of this method in actual operations. This study examines one work method, a work capacity assessment meeting, along with medical certificates B and their enclosures written by the doctor to the patient after a meeting. After the theoretical and methodological chapter, providing background information, the study describes the structure of the meeting and the medical certificate as a constructive factor. This is followed by a discussion on the manner of assessing the various domains of the patient s functional capacity and the decision-making based on the assessed factors. Next, the study moves on to examine the effect of patient involvements on the conclusions and decisions that professionals make at the meeting. In conclusion, the study looks into how the voices of the professionals and the customer are transferred to the medical certificate. The material of the study consists of 11 meetings recorded on video, of which eight are work capacity assessment meetings and three are rehabilitation examination meetings. The first type of meeting is attended by a patient and a number of professionals, while the latter is attended only by the professionals. All the patients, whose cases are discussed in the work capacity assessment meetings, have a musculoskeletal disorder, while the rehabilitation meetings are related to patients who all also have some additional problem. The study material also consists of seven medical certificates B, written after a work capacity assessment meeting. For the most part, the material has been collected by the conversation analysis method. Moreover, also discourse analysis and a rhetorical approach were used. By using conversation analysis, it is possible to study closely how interaction is built up at the meeting and to examine how the actors implement their institutional assessment tasks in a co-operation that takes its form turn by turn. The four main findings of the study are as follows: firstly, the meeting is structured to a great extent on the basis of the medical certificate form to various phases of the meeting and the headings of the certificate are seen as communicative affordances at the meeting, directed primarily to the professionals that have assessed the patient s work capacity with various tests. The medical certificate is the ethno-method of the doctor acting as the chairman of the meeting that functions in two directions: it constructs the meeting and constitutes the task of the professionals as they produce contents for it. Secondly, the study describes the ways that are used to assess the different domains of the patient s work capacity, how they are described at the meeting and how a decision is taken when the assessment information has been saturated in the opinion of the team. Thirdly, the study brings up ways, with which the patient can influence the conclusions and decisions made by the professionals at the meeting. The study showed that the patient can affect the preconditions of his or her own future and wellbeing. Fourthly, the study describes how the wealth of expressions at the meeting is transferred to the certificate as an argumentative micro-cosmos, where the patient is classified to be recommended for rehabilitation or disability pension. An important finding is also how objective and subjective information and the voices of actors at the meeting are transferred to the statement in a strategic and intentional manner, with an orientation to the decision that will be taken at the insurance institution. The study results can be utilized in the training of professionals and in developing the operations of organisations performing the assessment of the work capacity of people suffering from musculoskeletal disorders.