Calcium channel blockers and beta-blockers in relation to Parkinson's disease. A randomized and controlled pilot trial of beta-blockers for the treatment of recurrent syncope in patients with a positive or negative response to head-up tilt test.
We investigated the risk of Parkinson's disease (PD) associated with calcium channel blockers (CCBs) and beta-blockers in a population-based case-control study of 206 men and women between ages 35 and 89 with a new diagnosis of idiopathic PD between 1992 and 2002, and 383 controls without PD or other neurodegenerative disorders who were frequency matched on age, sex, duration of GHC enrollment and clinic. The adjusted odds ratio associated with ever use was 0.85 (95% confidence interval [CI]: 0.43, 1.66) for CCBs, and 1.20 (95% CI: 0.71, 2.03) for beta-blockers. We observed no association with PD risk for either class of medication in terms of duration, dose, number of prescriptions or pattern of use. The weakness of these associations and the absence of additional influence of dose or duration of use argue against any causal interpretation. The aim of this study was to assess the efficacy of lipophilic beta-blockers in preventing recurrent neurocardiogenic syncope and the value of head-up tilt test (HUT) in predicting response to therapy. The efficacy of beta-blockers in recurrent syncope is controversial. The value of HUT in predicting efficacy of therapy has not been investigated. Fifty-six patients (44+/-18 years, 36 women) with recurrent syncope (> 1 event in the last 6 months) of suspected neurocardiogenic origin were included in the study. Independent of the response to HUT, patients were randomized to receive metoprolol or propanolol at the maximal tolerated dose (28 patients, group A, 86+/-23 vs 98+/-29 mg/d) or no pharmacological therapy (28 patients, group B). The primary endpoint was the first recurrence of syncope. During the 1-year of follow-up, 20 patients of group A and 8 of group B had no recurrence. In group A, of 20 patients without recurrences 12 had a positive and 8 a negative HUT result while of 8 patients with recurrences 5 had a positive and 3 a negative response to HUT. In the group B, of 20 patients with recurrences 10 had a positive and 10 a negative HUT result while of 8 patients without recurrences 4 had a positive and 4 a negative response to HUT. In a multivariate Cox-regression analysis, medical therapy was the only independent factor for predicting recurrence of syncope (P = 0.004); HUT had no influence in this regard (P = 0.773). In conclusion, lipophilic beta-blockers appear efficacious in preventing recurrent syncope of suspected neurocardiogenic origin. The efficacy of therapy seems to be not predicted by HUT.
In view of this lack of evidence, it is impossible to determine whether beta-blocker therapy is effective and safe for the treatment of tremor in Parkinson's disease. The high frequency of bradycardia in one trial raises some concerns about the prescription of beta-blockers to normotensive elderly patients but the study was too small for the true degree of risk to be calculated.