Pergolide in Parkinson's disease: time for a change?

[Two cases of patients with Parkinson's disease developing valvular heart disease while taking cabergoline]

We experienced 2 patients of valvular heart disease in Parkinson's patients taking cabergoline. Patient 1 was a 79-year-old woman who began taking 4 mg cabergoline daily after being diagnosed with Parkinson's disease (PD) in June 2003. She presented with dyspnea in November 2005. The patient had cardiomegaly, pulmonary congestion, and pleural effusion, and an echocardiogram showed valvular heart disease in the form of aortic regurgitation (AR) (grade I), tricuspid regurgitation (TR) (grade I), and mitral regurgitation (MR) (grade III). Cabergoline was thought to have caused these phenomena, so it was replaced with pramipexole, and after administration of diuretics and angiotensin-converting enzyme inhibitors (ACEIs) the patient's symptoms gradually disappeared. MR, AR and TR also disappeared 3 months later. Patient 2 was a 74-year-old woman who presented with sluggish movement in April 2001 and subsequently developed Parkinson's. While being administered 700 mg levodopa (Menesit) and 4 mg cabergoline, the patient presented with shortness of breath in April 2005. An echocardiogram showed valvular heart disease in the form of MR (grade I) and TR (grade I). Heart function improved with the administration of diuretics. However, heart function again worsened in November 2005, and the patient presented with edema of the lungs and lower limbs. An echocardiogram in January 2006 showed worsening MR (grade III) and TR (grade II), and the patient also had pulmonary hypertension. ACEIs were administered along with diuretics and cabergoline was replaced with pramipexole, but the patient also developed malignant syndrome and disseminated intravascular coagulation (DIC) and later died. Patient 2 is the first case in Japan of death due to heart failure caused by the side effects of cabergoline. Caution is usually needed when treating a Parkinson's patient for valvular heart disease due to a dopamine agonist, and periodic checks for heart murmurs and echocardiography are crucial. When signs of heart failure develop during treatment with an ergot preparation of dopamine agonist, it is essential to immediately either stop the administration of the ergot preparation or change to a non-ergot preparation of dopamine agonist.

A review of the receptor-binding and pharmacokinetic properties of dopamine agonists

BACKGROUND

Dopamine agonists (DAs), which can be categorized as ergot derived and non-ergot derived, are used in the treatment of Parkinson's disease.

OBJECTIVES

This review describes the pharmacologic and pharmacokinetic properties of selected DAs and relates these characteristics to clinical outcomes, with an emphasis on adverse events.

METHODS

Relevant articles were identified through a search of MEDLINE (to May 2006) using the terms dopamine agonists (or each individual drug name) and pbarmacokinetics, metabolism, drug-drug interaction, interactions, CYP450, fibrosis, valvular heart disease, tremor, clinical trials, reviews, and meta-analyses. Abstracts from recent sessions of the International Congress of Parkinson's Disease and Movement Disorders were also examined. Clinical studies with <20 patients overall or <10 patients per treatment group in the final analysis were excluded. All DAs that were graded at least possibly useful with respect to at least 3 of 4 items connected to the treatment/prevention of motor symptoms/complications in the most recent evidence-based medical review update were included. This resulted in a focus on the ergot-derived DAs bromocriptine, cabergoline, and pergolide, and the non-ergot-derived DAs pramipexole and ropinirole.

RESULTS

Bromocriptine, cabergoline, pergolide, and ropinirole, but not pramipexole, have the potential for drug-drug interactions mediated by the cytochrome P450 (CYP) enzyme system. The occurrence of dyskinesia may be linked to stimulation of the dopamine D(1) receptor, for which cabergoline and pergolide have a similar and relatively high affinity; bromocriptine, pramipexole, and ropinirole have been associated with a lower risk of dyskinesias. The valvular heart disease (VHD) and pulmonary and retroperitoneal fibrosis seen with long-term use appear to represent a class effect of the ergot-derived DAs that may be related to stimulation of serotonin 5-HT(2B) (and possibly 5-HT(2A)) receptors. The incidence of valvular regurgitation was 31% to 47% with ergot-derived DAs, 10% with non-ergot-derived DAs, and 13% with controls.

CONCLUSIONS

As reflected in the results of the clinical trials included in this review, dyskinesia associated with DA therapy may be linked to stimulation of the D(1) receptor. Fibrosis (including VHD) seemed to be a class effect of the ergot-derived DAs. Each of the DAs except pramipexole has the potential to interact with other drugs via the CYP enzyme system.

Ropinirole, a non-ergoline dopamine agonist

Dopamine agonists have become indispensable in the treatment of Parkinson's disease. In every-day practice, however, the decision to select the best compound for an individual patient is rendered difficult because of the large number of substances available on the market. This review article provides a closer look at the experimental and clinical studies with ropinirole published so far. Ropinirole is a non-ergoline dopamine agonist which has been proven to be effective in both, monotherapy and combination therapy of idiopathic Parkinson's disease. In addition to ameliorating bradykinesia, rigor, and tremor, ropinirole facilitates the daily life and improves depressive moods of patients with Parkinson's disease. The long-term complications of levodopa are avoided, and problems commonly associated with levodopa treatment are reduced. Ropinirole appears to have a neuroprotective effect. In addition to Parkinson's disease, ropinirole has also been used successfully in the treatment of restless legs syndrome.