Magnitude Of Motor Response Research Articles

Open-label titration of apomorphine sublingual film in patients with Parkinson's disease and “OFF” episodes

IntroductionThe efficacy and safety of apomorphine sublingual film (APL-130277; APL) for the on-demand treatment of “OFF” episodes associated with Parkinson's disease (PD) was demonstrated in a double-blind trial. Herein we describe the ability of patients to receive effective and tolerable APL dose titration during the open-label titration phase. MethodsAdult patients with levodopa-responsive PD and “OFF” episodes were enrolled. In practically defined “OFF,” patients were observed for a FULL “ON” after their usual morning carbidopa/levodopa (CD/LD) dose and then after titration with APL following each increasing dose (10–35 mg). Antiemetic medication was administered for 3 days before initiation of titration and was continued throughout titration. Motor responses were evaluated predose and postdose using Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III score. Safety outcomes were evaluated. ResultsAmong 141 patients who enrolled in the study and received APL during open-label titration, 109 (77.3%) achieved a FULL “ON” (66.1% at 10–20 mg) and 10 did not. Patients who successfully completed APL dose titration tended to be younger, had a longer mean time since PD diagnosis, and had lower levodopa requirements than those who discontinued during titration for any reason. Change in MDS-UPDRS Part III scores from predose to 30 min postdose after titration with the effective dose of APL (n = 109) was similar across all dose groups. In a post hoc analysis, the magnitude of motor response with APL was ~2-fold higher than with CD/LD 15 min postdose, and the observed peak response occurred earlier with APL than with the trend seen for CD/LD (45 vs 90 min, respectively). Overall, the most common (≥10%) treatment-emergent adverse events (TEAEs) during APL dose titration were nausea (20.6%), yawning (12.1%), dizziness (11.3%), and somnolence (11.3%). Twelve patients discontinued due to TEAEs during APL dose titration, most commonly (≥2%) because of dizziness (2.8%), nausea (2.1%), and somnolence (2.1%). ConclusionAmong eligible patients with PD and “OFF” episodes who had their APL dose successfully titrated to an effective and tolerable level, most were able to do so within the first 3 titrated doses but some required further dose escalations. The use of APL can provide benefit for the treatment of “OFF” episodes.

Effects of Gabapentin on the Motor Response to Levodopa

Motor fluctuations and dyskinesias affect many parkinsonian patients chronically treated with levodopa. Imbalance between gabaergic direct and indirect striatopallidal pathways may originate them. Manipulating GABA neurotransmission may be effective in the treatment of these patients. Gabapentin is an antiepileptic drug that increases the synthesis and release of GABA. Previous studies suggest that gabapentin may be useful in Parkinson disease (PD). To know the effects of gabapentin on the motor response to levodopa in PD patients with motor complications. A randomized double-blind, placebo-controlled, cross-over trial with four weeks of treatment. A tertiary referral center. Twenty subjects with PD and motor fluctuations and dyskinesias on stable antiparkinsonian treatment, took gabapentin up to a maximum dose of 2.400 mg/d in three doses and placebo. Three levodopa challenges were performed: at the beginning of the study and at the end of each period of treatment (4 weeks). Basal (off) and best (on) motor status were assessed by the UPDRS III. Latency to peak effect, magnitude of motor response (difference between "on" and "off" scores in the UPDRS III), duration of motor response and severity and duration of dyskinesias after each levodopa challenge were assessed. Patients' diaries were administered. : Fifteen patients completed the study. A significant improvement in the basal UPDRS III resulting in a significant reduction in the magnitude of the motor response after gabapentin was obtained (P < 0.001). No other changes were observed, either on pharmacological parameters or in levodopa-induced dyskinesias. Number of daily hours spent in "on," "on with dyskinesias" and "off" also remained unchanged. Tolerance was good, dizziness being the most common side effect. Gabapentin improved parkinsonian symptoms (basal UPDRS III and magnitude of the motor response) following levodopa. This improvement was not reflected in the daily motor situation of patients. Dyskinesias remained unchanged. Gabapentin was well tolerated. Further studies are needed to know the impact of these results in the long-term.

Pharmacokinetic Optimisation of Dopamine Receptor Agonist Therapy for Parkinson??s Disease

Dopamine receptor agonists were originally developed as adjunctive therapies to ‘smooth out’ motor response fluctuations to levodopa in patients with advanced Parkinson’s disease. However, they are now used in the early stages of the disease, in monotherapy or combination with low doses of levodopa, to delay the onset of levodopa therapy and its complications. Oral dopamine agonists currently available worldwide for Parkinson’s disease include the older ergot derivatives bromocriptine and pergolide and the second generation non-ergoline compounds ropinirole and pramipexole. Other dopamine agonists that are used less frequently include cabergoline (a new ergoline drug, only recently released in some European countries as an antiparkinsonian drug), lisuride (an ergot derivative) and piribedil (an older non-ergot compound). Data on the pharmacokinetics of oral dopamine agonists, especially the older ergot derivatives, are scarce and mostly refer to small groups of healthy young individuals. All these agents, with the exception of pramipexole, are subject to extensive enterohepatic first-pass metabolism. Their bioavailability is low and shows high intra- and interindividual variability. The pharmacodynamic properties of dopamine agonists relevant to their antiparkinsonian effect have not been clearly defined. As a result, an optimal dosage schedule for the treatment of Parkinson’s disease is generally identified using highly individualised empirical assessment. This involves considerable time expenditure and creates difficulty for patients, who have to follow complex titration schedules. Dopamine agonists appear to have a low potential for pharmacokinetic interaction with levodopa. Few data have been reported on the effect of coadministration on the pharmacodynamics of levodopa. The available data indicate that pergolide and bromocriptine significantly increase the duration of the motor response to levodopa, while baseline motor effects and the magnitude of motor response are substantially unchanged. Cabergoline also significantly prolongs the motor response to a dose of levodopa in patients experiencing motor fluctuations, but baseline motor scores are also significantly improved, suggesting a long-lasting effect. Subcutaneous apomorphine is currently the only non-oral formulation of a dopamine agonist available; it is used as add-on rescue therapy for patients who have advanced Parkinson’s disease and a wide spectrum of complex motor, sensory, autonomic and cognitive ‘wearing-off ’ phenomena not controlled by optimal oral dopaminergic therapy. Attempts to deliver apomorphine and other soluble dopamine agonists by more practical non-oral routes, such as intranasally or transdermally, have so far been of limited clinical utility or are currently still under investigation.

Motor response to acute dopaminergic challenge with apomorphine and levodopa in Parkinson's disease: implications for the pathogenesis of the on-off phenomenon.

To evaluate the contribution of postsynaptic changes to motor fluctuations, three groups of parkinsonian patients with differing responses to treatment were acutely challenged with two dopaminergic drugs-apomorphine and levodopa-having different mechanisms of action. Forty two patients with Parkinson's disease (14 untreated, eight with a stable response to levodopa, and 20 with levodopa induced motor fluctuations) were challenged on two consecutive days with apomorphine and levodopa. The latency, duration, and magnitude of motor response was measured. A progressive shortening of mean latency after levodopa challenge was found passing from the untreated to the stable and fluctuating groups; the difference between untreated and fluctuating patients was statistically significant (P < 0.01). Response duration after levodopa challenge was similar in untreated and stable patients, whereas it showed a significant shortening in patients with motor fluctuations (P < 0.05 v both untreated and stable patients). When subcutaneous apomorphine was given, untreated patients had a longer response duration than those who had developed motor fluctuations (P < 0.05). Although baseline disability was significantly greater in the fluctuating patients than in the untreated and stable patients, the severity of residual parkinsonian signs after both apomorphine and levodopa challenge was similar for all three groups; as a result, the degree of improvement in parkinsonian signs after dopaminergic stimulation was substantially greater in more advanced than in early cases. Linear regression analysis also indicated that latency and duration after apomorphine challenge did not significantly correlate with those after levodopa challenge, whereas magnitude of response to apomorphine showed a strong positive correlation with that after levodopa challenge (r = 0.9, P < 0.001). The progressive shortening of motor response after both apomorphine and levodopa suggests that pharmacodynamic factors play an important part in determining the duration of motor response and argue against altered central pharmacokinetics of levodopa being principally responsible for the on-off effect. The widening response amplitude and increasing off phase disability occurring during disease progression are also critical factors in determining the appearance of motor fluctuations.

Kinetic-dynamic relationship of oral levodopa: possible biphasic response after sequential doses in Parkinson's disease.

The potential difference in the concentration-effect relationship of oral sequential doses of levodopa was explored in six Parkinsonian patients with complex fluctuating response. These patients showed "wearing-off phenomena" characterized by a transient worsening of motor function at the end of the first morning dose response to below baseline values and complained of a progressive reduction of levodopa effect during the day. A first standard levodopa dose was given in the morning, after an overnight fast and levodopa withdrawal. A second equal levodopa dose was administered immediately at the end of the first dose deterioration phase. Postimprovement worsening of motor response was also observed after the second levodopa dose in all patients. No significant difference in the pharmacokinetics of levodopa or in duration or magnitude of motor response could be appreciated between the two doses. These results further support the suggestion that, under controlled dietary conditions, plasma levodopa levels and effects relationship is reproducible between doses. Moreover, even when transient deterioration of motor function occurs between levodopa doses, the central dopaminergic system appears to remain responsive to the drug.