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PubMed1991

Pramipexole, a dopamine D2 autoreceptor agonist, decreases the extracellular concentration of dopamine in vivo.

Pramipexole (SND 919) is a dopamine D2 autoreceptor agonist which is structurally related to talipexole (B-HT 920), a potential antipsychotic agent. The aim of this study was to investigate the effects of pramipexole on the extracellular concentration of dopamine in vivo. Dopamine and its metabolites, 3,4-dihydrophenylacetic acid and homovanillic acid, were measured in the anterior striatum of freely moving rats by microdialysis and high-performance liquid chromatography with electrochemical detection. Pramipexole (30 and 100 micrograms/kg) caused long-lasting decreases in the extracellular concentrations of dopamine and its metabolites. Talipexole (30 micrograms/kg) produced similar effects. Sulpiride (5 mg/kg), a selective dopamine D2 antagonist, caused a transient increase in the concentration of dopamine and long-lasting increases in the concentrations of its metabolites; it also reversed the effects of pramipexole. SCH-23390 (100 micrograms/kg), a selective dopamine D1 receptor antagonist, caused a transient increase in the concentration of dopamine but did not affect the concentrations of the metabolites. SCH-23390 failed to reverse the effects of pramipexole. These results indicate that pramipexole reduces the extracellular concentrations of dopamine and its metabolites in vivo through a reversible interaction with the dopamine D2 receptor.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2004

Augmentation and tolerance with long-term pramipexole treatment of restless legs syndrome (RLS).

BACKGROUND: Dopaminergic agents have become first-line treatments for restless legs syndrome (RLS). The most common serious complications of L-Dopa treatment of RLS are "augmentation", in which RLS symptoms appear earlier during the day, and tolerance, in which medication effectiveness wanes over time. The aims of this study were to assess rates of augmentation and tolerance, and their interrelationship, with pramipexole treatment of RLS. PATIENTS AND METHODS: Retrospective assessment of all patients (N=59) treated for RLS with pramipexole for at least 6 months (mean duration=21.2+/-11.4 months) by the senior author. Pramipexole dosing and clinical follow-up were performed in a standardized fashion. L-Dopa was discontinued and other medications for RLS were tapered as tolerated. Rates of augmentation (need for earlier administration of the same dose of pramipexole) and tolerance (need for an increase in pramipexole dose) were determined. RESULTS: Augmentation developed in 32% (19/59), and tolerance occurred in 46% (27/59), of patients. These two complications were statistically related (P<0.05). The only clinical predictors of these complications were previous augmentation or tolerance to L-Dopa. CONCLUSIONS: Augmentation and tolerance are more common with extended pramipexole treatment of RLS than has been previously reported in preliminary studies. However, these complications are generally manageable by earlier dosing or small dose increases of this agent, and only rarely require medication discontinuation.

Adult↗
PubMed2000

Pramipexole in the treatment of advanced Parkinson's disease.

Pramipexole is a novel nonergoline dopamine agonist with a preference for the dopamine D3 receptor subtype. Its efficacy and safety in the treatment of advanced Parkinson's disease has been investigated in several clinical studies. This review provides a summary of the data currently available, particularly in reference to the recent results of the European clinical phase III study and the potential tremorlytic activity of pramipexole. Interim analysis of the open-label European clinical phase III study has provided evidence of long-term efficacy and safety of pramipexole. In another study pramipexole has been shown to be significantly superior to placebo with an improvement in tremor score by 48% (vs. 13% in the placebo group). In addition to its likely usefulness in the treatment of rest tremor in Parkinson's disease, data suggest that pramipexole is of interest due to its reported low frequency of cardiovascular and gastrointestinal side-effects. However, studies comparing pramipexole with other antiparkinsonian agents would be useful to further define its benefits in the treatment of tremor-dominant Parkinson's disease and to further document its favourable adverse event profile.

Benzothiazoles↗
PubMed2003

Reduction of oxidative stress in amyotrophic lateral sclerosis following pramipexole treatment.

Oxidative abnormalities have been identified both in familial amyotrophic lateral sclerosis (FALS) and the more prevalent sporadic ALS (SALS). Mitochondria dysfunction and toxic free radicals may play a role in this disease process, although the exact pathogenesis of both forms of ALS remains unknown. 2,3-DHBA is a hydroxylated salicylate by product that has been shown to be a reliable marker of increased free radical activity and is reliably assayed by HPLC. Following an oral salicylate load, we found elevated serum levels of 2, 3-dihydroxybenzoic acid (2,3-DHBA) and DHBA/salicylate in SALS subjects. Pramipexole has been shown to reduce oxidative stress and be neuroprotective in cell and animal models of neurodegeneration. We studied 12 SALS patients to determine the levels of 2,3-DHBA both before and after treatment with pramipexole. We found that pramipexole treatment up to 6 mg/day was well tolerated. The mean 2,3-DHBA serum levels were reduced by 45% and DHBA/salicylate ratios declined by 59% following treatment with pramipexole. SALS patients show apparent increases in systemic oxygen radical production that are reduced by pramipexole treatment at conventional doses, suggesting that pramipexole or related compounds may interrupt free radical production in SALS.

Aged↗
PubMed2005

Targeted antioxidative and neuroprotective properties of the dopamine agonist pramipexole and its nondopaminergic enantiomer SND919CL2x [(+)2-amino-4,5,6,7-tetrahydro-6-Lpropylamino-benzathiazole dihydrochloride].

Pramipexole has been shown to possess neuroprotective properties in vitro that are partly independent of its dopaminergic agonism. The site of neuroprotective action is still unknown. Using [(3)H]pramipexole, we show that the drug enters and accumulates in cells and mitochondria. Detoxification of reactive oxygen species (ROS) by pramipexole is shown in vitro and in vivo by evaluating mitochondrial ROS release and aconitase-2 activity, respectively. Pramipexole and its (+)-enantiomer SND919CL2X [low-affinity dopamine agonist; (+)2-amino-4,5,6,7-tetrahydro-6-l-propylamino-benzathiazole dihydrochloride] possess equipotent efficacy toward hydrogen peroxide and nitric oxide generated in vitro and inhibit cell death in glutathione-depleted neuroblastoma cells. IC(50) values ranged from 15 to 1000 microM, consistent with the reactivity of the respective radical and the compartmentalization of ROS generation and ROS detoxification. Finally, both compounds were tested in superoxide dismutase 1-G93A mice, a model of familial amyotrophic lateral sclerosis. SND919CL2X (100 mg/kg) prolongs survival time and preserves motor function in contrast to pramipexole (3 mg/kg), which shows an increase in running wheel activity before disease onset, presumably caused by the dopaminergic agonism. We conclude that both enantiomers, in addition to their dopaminergic activity, are able to confer neuroprotective effects by their ability to accumulate in brain, cells, and mitochondria where they detoxify ROS. However, a clinical use of pramipexole as a mitochondria-targeted antioxidant is unlikely, because the high doses needed for antioxidative action in vitro are not accessible in vivo due to dopaminergic side effects. In contrast, SND919CL2X may represent the prototype of a mitochondria-targeted neuroprotectant because it has the same antioxidative properties without causing adverse effects.

Aconitate Hydratase↗
PubMed2006

Comparison of pramipexole and modafinil on arousal, autonomic, and endocrine functions in healthy volunteers.

The noradrenergic locus coeruleus is a major wakefulness-promoting nucleus of the brain, which is also involved in the regulation of autonomic and endocrine functions. The activity of the locus coeruleus is believed to be tonically enhanced by a mesocoerulear dopaminergic pathway arising from the ventral tegmental area of the midbrain. Both modafinil, a wakefulness-promoting drug, and pramipexole, a D(2)/D(3)receptor agonist with sedative properties, may act on this pathway, with modafinil increasing and pramipexole decreasing locus coeruleus activity. The aim of this study was to compare the two drugs on alertness, autonomic and endocrine functions in healthy volunteers. Pramipexole (0.5mg), modafinil (200mg), and their combination were administered to 16 healthy males in a double-blind, placebo-controlled design. Methods included tests of alertness (pupillographic sleepiness test, critical flicker fusion frequency, visual analogue scales), autonomic functions (resting pupil diameter, light and darkness reflex responses, heart rate, blood pressure, salivation, core temperature), and endocrine functions (blood concentrations of prolactin, growth hormone, and thyroid stimulating hormone). Data were analysed by ANOVA. Pramipexole reduced alertness, caused pupil dilatation, increased heart rate, reduced prolactin and thyroid stimulating hormone, and increased growth hormone level. Modafinil caused small increases in blood pressure and core temperature, and reduced prolactin levels. The sedative effect of pramipexole and the autonomic effects of modafinil are consistent with altered activity in the mesocoerulear pathway; the pupil dilatation following pramipexole suggests reduced dopaminergic excitation of the Edinger-Westphal nucleus.

Adolescent↗
PubMed2005

Pramipexole has ameliorating effects on levodopa-induced abnormal dopamine turnover in parkinsonian striatum and quenching effects on dopamine-semiquinone generated in vitro.

OBJECTIVES AND METHODS: To clarify the effects of a non-ergot dopamine agonist pramipexole on levodopa-induced abnormal dopamine metabolism in the parkinsonian model, we examined striatal changes in dopamine and its metabolites after repeated administration of pramipexole and/or levodopa using 6-hydroxydopamine-lesioned hemi-parkinsonian mice. Moreover, the effects of pramipexole on dopamine-semiquinones were also accessed using an in vitro dopamine-semiquinone generating system to elucidate its neuroprotective property against dopamine quinone-induced neurotoxicity that appears as dopamine neuron-specific oxidative stress. RESULTS: Combined administration of pramipexole (0.5 or 1 mg/kg/day, 7 days) selectively suppressed the levodopa-induced (50 mg/kg/day) increase of striatal dopamine turnover in the parkinsonian side, but not in the non-lesioned side. In addition to the antioxidant properties previously reported, it was clarified that pramipexole scavenged dopamine-semiquinones generated in a dose-dependent manner either in simultaneous incubation or post-incubation. DISCUSSION: The neurotoxicity of dopamine quinones that appear as dopaminergic neuron-specific oxidative stress has recently been known to play a role in the pathogenesis of Parkinson's disease and neurotoxin-induced parkinsonism. Therefore, the present results revealed that pramipexole possesses neuroprotective effects against abnormal dopamine metabolism in excessively levodopa-administered parkinsonian brains and against cytotoxic dopamine quinones generated from excess dopamine, preventing consequently dopaminergic neuronal damage induced by excess dopamine or levodopa.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2003

Cabergoline, pramipexole and ropinirole used as monotherapy in early Parkinson's disease: an evidence-based comparison.

Dopamine agonists have been widely used as add-on to levodopa in the treatment of Parkinson's disease with motor fluctuations. However, the use of dopamine agonists in early Parkinson's disease and levodopa-naive patients is controversial. Although dopamine agonists have been compared with levodopa, no studies exist which directly compare one dopamine agonist with another. This evidence-based review compares the results of large published studies of early treatment of Parkinson's disease with dopamine agonists (cabergoline, ropinirole or pramipexole) with similar studies using levodopa. Because of their design, the common variables analysed in all studies were the proportion of patients who developed dyskinesia, those withdrawn from the trial and the mean change from baseline in Unified Parkinson's Disease Rating Scale (UPDRS) parts II and III scores. Cabergoline, pramipexole and ropinirole were similarly effective in reducing the risk for dyskinesia relative to levodopa (p < 0.01 for all three). The reduction in risk for dyskinesia was slightly more evident for pramipexole and ropinirole (p < 0.0001) than cabergoline (p = 0.0074). Odds ratios (95% confidence intervals [CI]) relative to levodopa were 0.38 (0.19-0.78) for cabergoline, 0.25 (0.13-0.47) for pramipexole and 0.31 (0.18-0.53) for ropinirole. The absolute risk reductions (95% CI) were, respectively, 8% (2.2-13.7), 20% (11.7-29.8) and 25% (13.6-36.7), ropinirole reducing the risk significantly more than cabergoline. The mean change from baseline UPDRS was similar for pramipexole and ropinirole (not evaluated for cabergoline). The proportion of withdrawn patients and the adverse effect profiles of the three agonists were similar to each other, with the exception of oedema, which was less prominent for ropinirole than for the other two agonists. Cabergoline, pramipexole and ropinirole are comparable choices for the delay of dyskinesia. Their adverse effect profiles are also similar, but they are less well tolerated than levodopa. The motor antiparkinsonian benefit of dopamine agonists is somewhat smaller than that of levodopa.

Age of Onset↗
PubMedDate not supplied

Pharmacology of pramipexole, a dopamine D3-preferring agonist useful in treating Parkinson's disease.

Pramipexole is a clinically effective nonergot dopamine agonist. Pramipexole's receptor interactions differ from ergot agonists in several ways. First, it has high selectivity for interacting with dopamine D2 subfamily receptors (D2, D3, and D4 receptor subtypes) and has little interaction with adrenergic or serotonergic receptors. Second, within the D2 subfamily, it has preferential affinity for the D3 receptor subtype, which, according to preclinical studies, could contribute additional efficacy for treatment of both motor and psychiatric syndromes in Parkinson's disease. Third, it has full intrinsic activity at dopamine D2 subfamily receptors. In addition to pramipexole's unusual receptor profile, whole-animal and cell culture studies suggest that pramipexole might provide neuroprotective effects through depression of dopamine metabolism, antioxidant effects, and stimulation of trophic activity. Pramipexole's demonstrated clinical efficacy for successful treatment in early disease for several years in the absence of L-dopa and as adjunctive therapy with L-dopa in late disease suggests a potential new paradigm for treatment of Parkinson's disease whereby new patients are initiated with pramipexole therapy and L-dopa is added only as necessary.

Aged↗
PubMed2001

The long-term safety and efficacy of pramipexole in advanced Parkinson's disease.

Objective: To assess the long-term safety and efficacy of pramipexole in advanced Parkinson's disease over a four year time period.Methods: This study is an open-label extension trial of pramipexole for Parkinson's disease open to patients completing a double-blind placebo controlled safety and efficacy trial of this drug. Three hundred and six patients entered the trial. These patients had moderate to severe PD (stage II-IV Hoehn and Yahr during off time) and were experiencing motor fluctuations. Patients were titrated over a six week period and then entered a maintenance phase which lasted up to 50 months. Patients were evaluated every 3 months using the Unified Parkinson's Disease Rating Scale (UPDRS II, III and IV) and modified Schwab and England scale (S/E).Results: Sixty-four percent (197) of the 306 patients who entered this study completed it. Patients showed steady improvement over the 6 week ascending dose interval when pramipexole was reintroduced into the trial as the open-label study medication. Over the duration of the trial patients slowly returned to their baseline levels. This was true for all measures evaluated except for the UPDRS part IV. On UPDRS part IV patients remained below their baseline score which indicated an improvement for the duration of the study. Patterns similar to the overall scores were seen when the individual components of the UPDRS scale part II for "on" and "off" periods and part III were evaluated. However tremor during "on" periods showed improvement over baseline for the duration of the trial. The most common adverse events secondary to pramipexole occurring in greater than 10% of patients included dyskinesias, asymptomatic orthostatic hypotension, dizziness, insomnia, and hallucinations.Conclusion: Pramipexole was well tolerated for up to 4 years. Pramipexole treatment appeared to show continued efficacy in the treatment of Parkinson's disease for 3 years in this open-label descriptive study. After 3 years there was a gradual return to baseline motor states perhaps suggesting progression of Parkinson's disease.

Journal Article↗
PubMed2000

Clinical characteristics of pramipexole-induced peripheral edema.

BACKGROUND: Pramipexole, a new dopamine agonist, effectively treats early and advanced Parkinson disease and restless legs syndrome. OBJECTIVES: To report the clinical features of and to investigate the predisposing factors and eventual outcomes in patients who developed peripheral edema (PE) following treatment with pramipexole. DESIGN: Retrospective case series in a tertiary referral center. RESULTS: Of the 300 patients who were receiving pramipexole therapy, 17 patients had mild to severe PE, which was attributable to the medication. Fifteen patients had Parkinson disease and 2 patients had restless legs syndrome. The mean (+/-SD) time of onset of PE after pramipexole therapy was started was 2.6 +/- 3.6 months (range, 0.25-11 months). The mean (+/-SD) dose at onset of PE was 1.7 +/- 1.0 mg/d (dose range, 0.75-3 mg/d) and the mean (+/-SD) dose when PE was at its maximum was 2.6 +/- 0.7 mg/d (dose range, 1.5-3 mg/d). In all cases, the PE rapidly abated with discontinuation of therapy, and in all cases that we rechallenged, it rapidly returned. The condition seemed to be dose dependent but also idiosyncratic, as we could not identify any predisposing features. It resulted in extensive medical evaluation in some patients and was only minimally responsive to diuretic therapy. CONCLUSION: Peripheral edema should be included among the potential adverse events associated with pramipexole therapy.

Adult↗
PubMed2004

Pramipexole in treatment-resistant depression: an extended follow-up.

We evaluated the long-term antidepressant safety and response of adjunctive pramipexole, a D2-D3 dopamine agonist, in the course of drug-resistant depression. Twenty-three patients with treatment-resistant major depressive episode (MDE) were followed up after a 16-week pramipexole add-on trial. Pramipexole was added to current treatment with TCA or SSRI, at increasing doses from 0.375-1.500 mg/day. The LIFE scale was administered at baseline of the acute trial, at Weeks 16, 32, and 48. Patients were analyzed for sustained remission (score= <2 at LIFE for at least 8 weeks) and recurrence (after remission score > =3 at LIFE for at least 2 weeks) of depression. Of 23 patients, 12 had major depression and 11 had bipolar depression (16 women; mean age=52.8 years). Mean age of onset and median duration of current MDE were 35.1 years and 6 months, respectively; all subjects had at least two prior MDEs. Mean pramipexole dose was 0.990 mg/day. Median duration of follow-up was 28 weeks. Mean baseline MADRS and CGI-S scores were 33.7+/-8.4 (sd) and 4.6+/-0.8, respectively. Median time to sustained remission from baseline was 10 weeks and overall 60.9% (14/23) of subjects recovered within Week 22. Recurrence of depression occurred in 35.7% (5/14) of remitters after Week 24 and within Week 28 from remission. Although there were no sleep attacks, two cases of hypomania and one case of psychotic mania occurred at Weeks 22, 24, and 30, respectively. Pramipexole augmentation of antidepressant treatment was relatively safe and presumably effective in the long-term course of treatment resistant depression.

Acute Disease↗
PubMed1997

Steady-state pharmacokinetic properties of pramipexole in healthy volunteers.

Pramipexole is a dopamine receptor agonist that has proved effective in the treatment of Parkinson's disease. The pharmacokinetic properties of pramipexole at steady-state concentrations were studied in 16 healthy men and women at four dose levels throughout the range recommended for Parkinson's patients. Plasma and urine samples collected within the four dose intervals were assayed for concentrations of pramipexole, using high-performance liquid chromatography. The total oral clearance for all participants was 419 mL/min. The mean volume of distribution and elimination half-life for all participants was 486 +/- 93.2 L and 12.9 +/- 3.27 hours. Concentrations of pramipexole were proportional to dose, although the drug's pharmacokinetic properties differed between men and women. The area under the concentration-time curve for each dose level was 35% to 43% greater in women, mainly because of a 24% to 27% lower oral clearance. The mean creatinine clearance in men and women was 112 +/- 12.8 mL/ min/1.73 m2 and 80.9 +/- 15.6 mL/min/1.73 m2, respectively. The renal clearance of pramipexole accounts for approximately 80% of oral clearance, and there was a significant correlation between renal and creatinine clearances. The influence of gender could not be distinguished from the influence of age and the resulting reduced creatinine clearance, but the measurement of pharmacokinetic properties produced linear results in both men and women.

Adult↗
PubMed2003

Double-blind, single-dose, cross-over study of the effects of pramipexole, pergolide, and placebo on rest tremor and UPDRS part III in Parkinson's disease.

Tremor is one of the cardinal signs of Parkinson's disease (PD) but its response to antiparkinsonian medication is variable. It has been postulated that pramipexole may have a stronger antiparkinsonian tremor effect than pergolide, another direct acting dopamine agonist medication, possibly because the former has preferential affinity for the dopamine D3 receptor. The purpose of this pilot study was to compare the effects of a single oral dose of either pramipexole (Pr) or pergolide (Pe) or placebo (Pl) on parkinsonian tremor and the motor (part III) subsection of the UPDRS. Ten patients (6 men, 4 women), mean age 65.3 years, mean duration from diagnosis of 2.6 years, with tremor dominant PD were recruited. On three separate occasions a single dose of pramipexole (salt) 500 microg, pergolide 500 microg or placebo were administered in random order to each patient, who were pretreated with domperidone and had their antiparkinsonian medication withheld from midnight before study. After each medication patients were assessed at baseline and then every 30 min for 4 hr using a 0 to 10 tremor rating scale and the UPDRS (part III) in a double-blind protocol. Adverse effects were systematically recorded. The results demonstrate that 500 microg of either pramipexole or pergolide reduced PD rest tremor scores to a similar degree, which at peak effect was significantly greater than placebo (respectively Pe v Pl: P < 0.006, Pr v Pl: P < 0.033). The two active drugs also had weaker beneficial effects on the UPDRS part III. Pergolide, however, was significantly more likely than pramipexole to cause nausea (P = 0.005) or vomiting (P = 0.014).

Aged↗
PubMed2003

Randomized, double-blind, 3-month parallel study of the effects of pramipexole, pergolide, and placebo on Parkinsonian tremor.

We compared the antitremor effect of pramipexole, pergolide, or placebo in Parkinson's disease (PD). A double-blind, randomly controlled, parallel protocol was deployed to examine the effects of placebo, pergolide, and pramipexole [doses escalated to 1.5 mg three times daily (t.i.d.) over 3 months] on a compound Tremor Index (TI) and Unified Parkinson's Disease Rating Scale (UPDRS) part III. Thirty PD patients (19 men, 11 women; mean age 69 years, range 54-80 years; mean disease duration 3.9 years, range, 0.5-10 years) participated in the study, with 10 patients in each arm. Six subjects failed to complete the study (4 on pergolide and 2 on placebo). Analysis of covariance demonstrated strong evidence for a treatment effect on both TI and UPDRS III. There was no significant difference between the active treatments on either TI or UPDRS III. Both pergolide and pramipexole were significantly better than placebo. The results indicate that pergolide and pramipexole (1.5 mg t.i.d.) have similar anti-PD tremor and UPDRS III actions that are significantly superior to placebo. Patients on pergolide were more likely to drop out because of adverse events than those on pramipexole.

Aged↗
PubMed2002

[Pramipexole in Parkinson disease. Results of a treatment observation].

Pramipexole is a novel, internationally available selective nonergot D2 dopamine agonist. The effectiveness, tolerability, and safety of pramipexole have been extensively proven in controlled trials in patients in the early and advanced stage of Parkinson's disease as monotherapy and in combination with L dopa. These trials indicated specific activity against tremor, anhedonia, and depression. Therefore, the present prospective, multicenter postmarketing surveillance study evaluated for the first time to what extent the results from the controlled pramipexole trials could be replicated under routine conditions in neurological practice and clinics. Modern scales were applied for the assessment of tremor and mood, i.e., the Short Parkinson's Evaluation Scale (SPES), the Tremor Impact Scale (TIS), and the German version of the Snaith-Hamilton Pleasure Scale (SHAPS-D). In 298 German Centers, 657 Parkinson's patients (365 men, 292 women) in advanced disease stages were treated with pramipexole in combination with levodopa. The average ages (+/- SD) were 67 (+/- 8.9) years for men and 69 (+/- 9.4) years for females. Motor functioning, especially tremor, motor complications, depression, and activities of daily living improved highly significantly (P < 0.0005), including self-rating by the patients. The dosage of levodopa could be reduced on average by 8% (P < 0.0001). This might contribute to a slowing of the disease progression in the long run. Dropouts due to side effects were observed only in 3.5% of the patients. Using new assessment scales suitable for routine application allowed confirmation of the results from controlled clinical trials with regard to tremor, anhedonia, and depression. The average daily dosage of pramipexole prescribed was 1.05 mg and thus was definitely lower than the average daily dosages of 2.35-2.66 mg used in controlled trials. This signifies that the option to adjust dosage according to effectiveness and tolerability under routine conditions yields a considerably lower incidence of adverse effects.

Aged↗
PubMed2006

Comparison of pramipexole and amisulpride on alertness, autonomic and endocrine functions in healthy volunteers.

RATIONALE: In a previous study in healthy volunteers, the anti-Parkinsonian drug pramipexole caused sedation and pupil dilatation, consistent with the stimulation of inhibitory D(2)/D(3) autoreceptors on the ventral tegmental area dopaminergic neurones. The sedation may be related to the removal of the dopaminergic excitation of the locus coeruleus (via the meso-coerulear pathway), whereas the pupil dilatation may be due to the removal of the dopaminergic excitation of the Edinger-Westphal nucleus (via a putative meso-pupillomotor pathway). OBJECTIVES: We investigated the hypothesis that amisulpride, a D(2)/D(3) receptor antagonist, would have effects opposite to those of pramipexole on alertness, pupillary and endocrine functions. MATERIALS AND METHODS: Pramipexole (0.5 mg), amisulpride (50 mg), and their combination were administered to 16 healthy males in a balanced, cross-over, double-blind design. Tests included measures of alertness (Pupillographic Sleepiness Test, critical flicker fusion frequency, visual analogue scales), pupillary functions (resting pupil diameter, light and darkness reflex responses), non-pupillary autonomic functions (heart rate, blood pressure, salivation, core temperature), and endocrine functions [blood concentrations of prolactin, growth hormone (GH) and thyroid stimulating hormone (TSH)]. Data were analysed by ANOVA. RESULTS: Pramipexole reduced alertness and pupillary light reflex response amplitude, tended to reduce core temperature, reduced prolactin levels and increased GH levels. Amisulpride reduced pupil diameter, increased the amplitude of the light reflex response and prolactin and TSH levels. CONCLUSIONS: The opposite effects of pramipexole and amisulpride on alertness, pupillary function and pituitary hormone levels are consistent with their interactions with inhibitory D(2)/D(3) receptors on VTA neurones and in the tuberoinfundibular system.

Adult↗
PubMed2006

Pramipexole versus sertraline in the treatment of depression in Parkinson's disease: a national multicenter parallel-group randomized study.

In addition to treating the motor symptoms of Parkinson's disease, the dopamine agonist pramipexole has shown an antidepressant effect. The trials, however, included patients with motor complications, raising the question of whether the antidepressant benefit represented only a treatment-related motor improvement. To address this issue, we have conducted a 14-week randomized trial comparing pramipexole with an established antidepressant in patients without motor complications. At seven Italian centers, 67 Parkinsonian outpatients with major depression but no history of motor fluctuations and/or dyskinesia received open-label pramipexole (at 1.5 to 4.5 mg/day) or sertraline (at 50 mg/day). In both groups, the Hamilton Depression Rating Scale (HAM-D) score decreased throughout 12 weeks of treatment, but in the pramipexole group the proportion of patients who recovered, as defined by a final HAM-D score </= 8,was significantly higher, at 60.6% versus 27.3% (p = 0.006). Patients' self-ratings improved in both groups. All adverse events were mild or moderate, but five patients (14.7%) withdrew from the sertraline group. Despite the absence of motor complications, the pramipexole recipients showed improvement on the Unified Parkinson's Disease Rating Scale (UPDRS) motor subscore. We conclude that dopamine agonists may be an alternative to antidepressants in Parkinson's disease.

Aged↗