A 12-week, placebo-controlled study (6002-US-006) of istradefylline in Parkinson disease

BACKGROUND

The safety and efficacy of istradefylline, a selective adenosine A(2A) receptor antagonist, was evaluated in a 12-week, double-blind study in levodopa-treated Parkinson disease (PD) subjects with motor complications.

METHODS

Levodopa-treated PD subjects (n = 395) received istradefylline 20 mg/day (n = 163), istradefylline 60 mg/day (n = 155), or placebo (n = 77) at 40 sites. The primary efficacy variable was the change in the percentage of time per day spent in the OFF state. Secondary measurements assessed change in ON time, Unified Parkinson's Disease Rating Scale, and Clinical Global Impression. Safety monitoring included clinical laboratory, electrocardiograms, vital signs, physical/neurologic examinations, and adverse events (AEs).

RESULTS

Changes from baseline to endpoint in the percentage OFF time in the active groups compared with placebo were -4.35% (95% CI -8.16 to -0.54; p = 0.026) for istradefylline 20 mg/day and -4.49% (95% CI -8.35 to -0.62; p = 0.024) for 60 mg/day; these changes were significant (analysis of covariance). For total hours, istradefylline demonstrated mean differences from placebo of -0.64 hours (95% CI -1.30 to 0.01) for 20 mg/day and -0.77 hours (95% CI -1.44 to -0.11) for 60 mg/day (p = 0.065; overall treatment effect). Clinical response occurred by the second week and was maintained throughout the study. Istradefylline was well tolerated. The common AEs were dyskinesia, nausea, dizziness, and hallucinations.

CONCLUSIONS

Istradefylline demonstrated a significant reduction in the percentage of awake time per day spent in the OFF state, which resulted in a clinically meaningful reduction in OFF time, without an increase in ON time with troublesome dyskinesia, and was well tolerated as adjunctive treatment to levodopa in Parkinson disease.

Comparison of Butorphanol Nasal Spray and Fiorinal With Codeine in the Treatment of Migraine

Butorphanol tartrate is a synthetic mixed agonist-antagonist opioid analgesic. Its transnasal dosage form, which may be self-administered when the use of an opioid analgesic is appropriate, was previously shown to provide rapid relief of migraine pain. In this double-blind, parallel-group, outpatient study, we compared butorphanol nasal spray 1 mg followed in 1 hour by an optional second 1-mg dose with the orally administered analgesic, Fiorinal with Codeine (one capsule containing butalbital 50 mg, caffeine 40 mg, aspirin 325 mg, and codeine phosphate 30 mg). Patients (N=321) were assigned by randomization to one of two treatment groups (butorphanol or Fiorinal with Codeine) and instructed to self-administer medication when migraine pain reached an intensity of moderate or severe and to record study-related events in a diary for 24 hours posttreatment. Efficacy analyses were performed on data from 275 patients who took study medication and returned a patient diary; 136 in the butorphanol group and 139 in the Fiorinal with Codeine group. During the first 2 hours after treatment, butorphanol was more effective than Fiorinal with Codeine in treating migraine pain as measured by pain intensity difference scores, percentage of responders (pain decreased to mild or none), percentage of pain-free patients, and degree of pain relief, with a more rapid time to onset of 15 minutes. A similar percentage of patients in the two groups used rescue medication during the first 4 hours, after which more butorphanol-treated than Fiorinal with Codeine-treated patients used rescue medication. Butorphanol patients had more side effects, less improvement in digestive symptoms, and less improvement in functional ability than Fiorinal with Codeine patients.

Dose frequency and dose interval compliance with multiple antiepileptic medications during a controlled clinical trial

Compliance with medication regimens and clinical trial schedules was evaluated during a study of vigabatrin (VGB), an antiepileptic drug (AED). Medication Event Monitors (MEMS, Aprex Corp., Fremont, CA, U.S.A.) were provided to monitor use of VGB and other AEDs administered to 111 patients at 10 sites. MEMS reports showed the number of doses administered daily, times of doses, and intervals between doses. The 66 patients whose data were evaluable took VGB as prescribed (twice daily, b.i.d.) on 89 +/- 7% of days in the clinical trial (mean 189 +/- 63 days). However, only 66 +/- 24% of doses were taken within the 9-15-h dose interval window for twice-daily dosing, a lower rate than that for dose frequency compliance (p < 0.001). Concomitant medications prescribed b.i.d. (n = 66) (86 +/- 11% dose frequency compliance) were taken at lower rates than VGB (p < 0.02). Interval compliance also was lower for concomitant b.i.d. medications (59 +/- 26%) than for VGB (p < 0.01). Dose frequency compliance for thrice-daily (t.i.d.) medications (n = 36) was 80 +/- 18 and 40 +/- 19% for interval compliance (6-10 h) (both p < 0.0001 vs. VGB). Dose frequency compliance for four times daily (q.i.d.) medications (n = 23) was 80 +/- 23 and 33 +/- 18% for interval compliance (4-8 h) (both p < 0.0001 vs. VGB). Patients at eight sites did not use MEMS properly, often for practical reasons, voiding including of data for 93 medications (32%) because of noncompliance with the study design to monitor compliance.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolactin secretion following repetitive seizures

We studied serum prolactin levels after 24 seizures occurring in eight subjects. Video-EEG intracranial monitoring confirmed temporal or frontal partial seizures. Seizure type, focus, and duration were similar for seizures with and without significant postictal prolactin elevations. The seizure-free interval (the time between seizures) varied considerably. Seizures occurring after longer seizure-free intervals (31.75 to 240 hours) showed robust prolactin responses. After shorter seizure-free intervals (1.07 to 25.42 hours), prolactin responses were reduced. This suggests that the amount of releasable prolactin is limited, depleted by seizures, or perhaps inhibited by prolactin feedback. Seizure-free intervals should be considered when interpreting prolactin levels.

Effects of differing dosages of vigabatrin (Sabril) on cognitive abilities and quality of life in epilepsy

Vigabatrin (VGB) prevents seizures by irreversible inhibition of gamma-aminobutyric acid (GABA) transaminase and a resulting increase in GABA levels. We evaluated the cognitive and quality-of-life (QOL) effects of VGB in a double-blinded, add-on, placebo-controlled, parallel group dose-response study of patients with focal epilepsy whose complex partial seizures (CPS) were difficult to control. In a single investigation, patients were randomly assigned to placebo (n = 40), 1 g VGB (n = 36), 3 g VGB (n = 38), or 6 g VGB (n = 32), treated for 12 weeks after a 6-week dose escalation period, and tested at the end of the baseline period and at the end of the treatment period with eight cognitive measures and three tests of mood and adjustment. The patient groups were highly similar at study entry. Results at the end of the study showed substantial relief from seizures. The Digit Cancellation Test showed decreases in performance with increasing doses of VGB. Performance on no other test showed any decrement with increasing dosage. Relief from seizures was not associated with changes on the psychological tests. VGB is a useful antiepileptic drug (AED) that has little impact on tests of either cognitive abilities or QOL, even at a high dose.

Use of ex vivo magnetic resonance imaging to detect onset of vigabatrin-induced intramyelinic edema in canine brain

Vigabatrin (VGB) causes intramyelinic edema (microvacuolation) in brain of dogs and rodent, which has encouraged development of noninvasive methods to monitor for this effect during clinical trials. We report the qualitative ex vivo magnetic resonance imaging (MRI) changes observed in a neuropathology study in dogs to detect time of onset and regression of VGB-induced intramyelinic edema. Beagles were randomly assigned to 18 groups of 6 dogs per group and administered vigabatrin orally (p.o.) at a dose of 300 mg/kg/day (2 males, 2 females) or placebo (1 male, 1 female). Animals were killed and examined at weekly intervals during the 12 weeks of treatment and at 1, 2, 4, 8, 12, and 16 weeks after discontinuation of drug treatment. Myelin microvacuolation in thalamus, hypothalamus, and fornix were noted histologically after 4-5 weeks of treatment. Increases in MRI T2 intensity were observed in hypothalamus after 4 weeks and in thalamus and columns of the fornix after 7 weeks. Both MRI T2 intensity and microvacuolation continued to increase during 12-week VGB treatment. When VGB treatment was discontinued after 12 weeks, both MRI T2 intensity and microvacuolation began to decrease. Sixteen weeks after VGB discontinuation, histopathology had returned to normal and MRI examination demonstrated a marked trend toward reversal of the increased T2 signal intensity. MRI thus has potential as a noninvasive surveillance technique in certain experimental and clinical conditions associated with intramyelinic edema.

MRI monitoring of vigabatrin-induced intramyelinic edema in dogs

Chronic administration of vigabatrin (gamma-vinyl GABA) in dogs produces reversible microvacuolation (intramyelinic edema) in discrete brain regions. Histologic changes are most notable in the columns of the fornix and regions of the hypothalamus, thalamus, optic tract, and hippocampus. In an attempt to image these changes in vivo, we performed high-field MRI on seven treated and four control dogs at baseline and after 15 weeks of dosing with vigabatrin (300 mg/kg/d). All dogs underwent parallel electrophysiologic assessment to determine the effects of vigabatrin on afferent conduction. At 15 weeks, all treated dogs showed increased T2- and decreased T1-weighted signals, with changes from baseline most prominent in the columns of the fornix and to a lesser degree in the surrounding hypothalamus and thalamus. MRIs performed on control dogs were unremarkable. We then perfused a random selection of four treated and two control dogs and imaged their brains ex vivo prior to sectioning. Ex vivo imaging confirmed the in vivo findings and strongly correlated with both electrophysiologic and subsequent histopathologic findings. Imaging was repeated in the surviving dogs 5 and 12 weeks after discontinuation of dosing. Signal abnormalities in the treated dogs progressively diminished during recovery, paralleling the electrophysiologic and histopathologic results. These findings demonstrate that MRI can detect signal changes anatomically congruent with vigabatrin-induced intramyelinic edema and suggest that MRI may provide a useful noninvasive tool for monitoring patients during clinical trials.

Evaluation of the effects of vigabatrin on cognitive abilities and quality of life in epilepsy

We evaluated the psychological effects of the antiepilepsy drug vigabatrin in a randomized multicenter double-blind placebo-controlled parallel group study that compared 3 grams oral vigabatrin with placebo as daily add-on therapy in patients with focal epilepsy whose complex partial seizures were difficult to control. Testing at baseline and after 12 weeks of vigabatrin (n = 83) or placebo (n = 85) used eight measures of cognitive abilities and three of mood and adjustment. The vigabatrin and placebo groups were highly similar at entry into the study. At the end of the study, there were no differences between the vigabatrin and placebo groups on any cognitive variable or on any measure of mood and adjustment. Analysis of the results related to relief from seizures demonstrated only chance findings. In a similar manner, there were no relationships between vigabatrin serum levels at the end of the study and changes on measures of abilities and adjustment. Vigabatrin appears to be a useful antiepilepsy drug with little impact upon tests of either cognitive abilities or quality of life.

Sequential neuropathology of dogs treated with vigabatrin, a GABA-transaminase inhibitor

Vigabatrin (Sabril) is a gamma-aminobutyric acid-transaminase (GABA-T) inhibitor that is effective in the treatment of certain types of drug-resistant or uncontrolled epilepsy but is known to cause microscopic vacuolation (intramyelinic edema) in the brains of treated rats, mice, and dogs. The effects of high oral doses (300 mg/kg/day) of vigabatrin administered orally to Beagle dogs were studied during treatment weeks 1-12 and recovery weeks 13, 14, 16, 20, 24, and 28. Emesis, loose stools, and anorexia and 3 drug-related deaths were observed during the first 4 wk of treatment but were virtually nonexistent thereafter because of adaptation to the drug aided by food supplementation. In more sensitive areas of the brain (columns of the fornix, thalamus, and hypothalamus), microscopic quantitative differences between background vacuolation in controls and drug-related vacuolation in treated dogs could be delineated after 4 wk, generally reached highest levels of severity between 8 and 12 wk, and were reversible upon cessation of dosing. Inhibition of brain GABA-T and elevation of brain GABA were noted after 1 wk of treatment. During the course of treatment vigabatrin ranged between 4-17 nmol/ml (plasma) and 42-1,570 nmol/ml [cerebrospinal fluid (CSF)] while CSF GABA concentrations were 4-32 nmol/ml (treated dogs) and 0.1-0.6 nmol/ml (control dogs). Although the cause of vigabatrin-induced microvacuolation is unknown, the results of the study demonstrated that GABA-T inhibition with subsequent GABA elevation occurred within the first week of treatment and was followed by the onset of detectable microvacuolation several weeks later.

Pharmacokinetics of vigabatrin following single and multiple oral doses in normal volunteers

The pharmacokinetics of vigabatrin were investigated after single and multiple oral doses in two groups of 24 healthy male volunteers. Vigabatrin was well tolerated by the volunteers; headache was the most frequently reported adverse event. There were no clinically remarkable changes in serum chemistry, urinalysis, or hematology attributable to vigabatrin. For the single-dose study, a stepwise linear contrast method was used to assess dose proportionality. The results showed that vigabatrin exhibited dose linear pharmacokinetics after single oral doses ranging from 0.5 to 4.0 g. Slight changes in the terminal phase half-life and renal clearance were evident in the higher dosage groups. These changes with increasing dose of vigabatrin were relatively minor and not considered to be clinically important. Evaluation of the multiple-dose pharmacokinetics indicated that vigabatrin exhibited dose linearity over the range of 0.5 to 2.0 g administered every 12 hours. The terminal phase half-life and renal clearance of vigabatrin during multiple dosing were consistent with that after single doses. During multiple dosing, steady-state concentrations of vigabatrin were reached on the second day of dosing, and drug accumulation was minimal.

Presurgical electroencephalographic patterns and outcome from anterior temporal lobectomy

We reviewed data from 48 patients after anterior temporal lobe resection for medically intractable epilepsy. All had ictal electro-encephalographic (EEG) evidence of unilateral temporal lobe onset. Depth electrodes were used in 19 patients. Successful surgical outcome correlated significantly with factors that suggested a temporal lobe focus, particularly in the interictal scalp EEG. The most successful outcome occurred in patients with well-localized unilateral interictal temporal spikes (100% improved). The group with well-localized bilateral temporal spikes also did well (76% improved). Patients with extratemporal spread of the interictal spike on scalp EEG, either unilaterally or bilaterally, did less well. Only one third improved, despite extensive extracranial and intracranial monitoring, when indicated. The interictal scalp EEG may be the only EEG necessary for the presurgical evaluation of selected patients with intractable temporal lobe epilepsy.

Utilization of a two-channel, microprocessor-based EEG device for monitoring cognitively vulnerable patients

Several experiments were conducted to validate the use of a two-channel microprocessor-based electroencephalographic (EEG) device for detecting changes in EEG background rhythm in the clinic or at the bedside. The reliability of background measures in healthy individuals was evaluated by obtaining EEG data on 20 control subjects on two occasions separated by at least 1 day. The sensitivity to an experimental toxic encephalopathy was evaluated using measures of EEG and the Buschke Memory Selective Reminding Test after the administration of scopolamine hydrobromide, 0.86 mg subcutaneously, to three healthy volunteers. Postdrug measures of the EEG showed significant group differences from controls at 1 and 2 hours for relative alpha and relative theta power. The drug-induced change for each individual exceeded the predicted range calculated from data on control subjects. These findings suggest the feasibility and the potential utility of this method. This approach was extended to the elderly with measures on 102 subjects (average age, 85 years) living in an institutional setting. EEG measures in the population were of acceptable reliability and were significantly correlated with Mini-Mental State Examination (MMSE) scores (r = -.375 for theta and .357 for beta). Preliminary findings suggest that this method may detect metabolic encephalopathies in the elderly. The study demonstrates the potential value of this approach and suggests the need for further research.

Bicycling movements as a manifestation of complex partial seizures of temporal lobe origin

Alternating movements of the limbs during a seizure, especially bicycling movements of the legs, are often taken as strong evidence for the psychogenic origin of seizure activity in an adult population. A recent review of pseudoseizure manifestations concluded that alternating limb movements were "highly characteristic of pseudoseizures." We report two adult patients with complex partial seizures of temporal lobe origin, confirmed by ictal video EEG recording, in whom bicycling movements were the prominent ictal manifestation. Bicycling occurred 5-30 s after ictal onset and lasted 15-30 s. Use of video EEG recording continues to increase our understanding of the wide range of behaviors which may occur in the course of an epileptic seizure, particularly complex partial seizures. Few absolute clinical criteria remain to distinguish epileptic seizures from pseudoseizures. These two cases and one other reported case clearly remove bicycling movements from that category.

Initial experience with SPECT imaging of the brain using I-123 p-iodoamphetamine in focal epilepsy

Nineteen patients with complex partial seizures refractory to medical treatment were examined with routine electroencephalography (EEG), video EEG monitoring, computed tomography or magnetic resonance imaging, neuropsychological tests and interictal single photon emission computed tomography (SPECT) with I-123 iodoamphetamine (INT). In 18 patients, SPECT identified areas of focal reduction in tracer uptake that correlated with the epileptogenic focus identified on the EEG. In addition, SPECT disclosed other areas of neurologic dysfunction as elicited on neuropsychological tests. Thus, IMP SPECT is a useful tool for localizing epileptogenic foci and their associated dynamic deficits.

Memory deficits before and after temporal lobectomy: effect of laterality and age of onset

Laterality and age of onset effects on semantic and figural memory were evaluated in 30 right-handed, left speech dominant (amobarbital test) patients with epilepsy before and after temporal lobectomy. There were no effects of focus on WAIS-R IQ scores. Early onset (less than or equal to 5 years) was associated with lower IQ and memory (WMS). Left Temporal (LT) patients showed worse semantic than figural memory preoperatively. Unexpectedly, early onset LT had marked postoperative decline of figural memory, whereas late onset LT patients showed the previously reported worsening of semantic memory. Right Temporal (RT) lobectomy patients, in contrast, improved in both semantic and figural memory regardless of age of onset. A "crowding effect" was suggested by the decline in figural memory following surgery in the early onset LT patients who remained stable or improved in semantic memory. Results indicate the need to incorporate age of onset of seizures into laterality models of memory function following unilateral temporal-hippocampal resection.

Magnetic resonance imaging after corpus callosotomy

Magnetic resonance imaging (MRI) can visualize the extent of corpus callosotomy performed for medically intractable epilepsy not amenable to focal surgery. Five patients underwent complete callosotomy and one an anterior callosotomy, aged 19 to 24 years, 21 to 53 months (prior to scanning). T1 images showed complete absence of the callosal shadow in five cases and visualization of the genu and splenium in the sixth case. T2-weighted pulse sequence spin-echo MRI showed intense image throughout the region of the entire callosum in the two cases with the longest postoperative course. The two middle cases showed intense T2 signal from the splenium, and the two latest showed no increase in T2 signal. We believe the increase in T2 signal in the transected callosum may represent an in vivo example of anisomorphic gliosis. T1 images demonstrate the anatomic extent of transection, while T2 images demonstrate the chemical and pathophysiologic sequence of transection. Thus, MRI is the imaging test of choice to evaluate callosotomy patients.

Contralateral and ipsilateral control of fingers following callosotomy

The extent of ipsilateral control of the distal limbs is not documented. In this experiment visuo-motor control of fingers was investigated in two callosotomy patients. A substantial amount of ipsilateral control was evident, especially for the left hand fingers. Ipsilateral control of the right hand was evident for the thumb and index fingers, but not for the other fingers. Left hand fingers did not vary significantly in degree of ipsilateral control.

Ictal blindness and status epilepticus amauroticus

Five cases of ictal blindness are presented. All are documented to be ictal by simultaneous EEG monitoring during the period of blindness. In three cases, the blindness was complete; in two, it manifested as a homonymous hemianopia. Three cases (including the two with hemianopia) were secondary to vascular lesions; one case was due to a metastatic lesion; and there was one case of idiopathic epilepsy. Age ranged from 13 to 74 years. In all cases, the blindness was reversible with anticonvulsant therapy. All cases but one lasted from hours to days, meeting a criterion of "status epilepticus amauroticus." In the literature, ictal blindness is seldom reported and even less often documented. Unexplained cortical blindness might represent unrecognized seizure activity more often than is appreciated.

Hemispheric control of the writing hand: the effect of callosotomy in a left-hander

We report a case of a left-hander with left hemispheric language. After callosotomy, he could use the left hand to write only random letters and digits, and he became right-handed for writing. Therefore, writing by left-handers with left hemispheric language dominance may be accomplished by transcallosal transmission of the linguistic content from the left hemisphere to the right.

Mutism as a consequence of callosotomy

Transient mutism has been reported following commissurotomy and callosotomy. The cause for this mutism is unknown. A case of mutism following callosotomy is presented, and the preoperative and postoperative data on neurological, physiological, and psychological functioning are discussed. The data suggest that the mutism is not caused by general intellectual deterioration, cortical lesion, or peripheral damage affecting speech production. The syndrome may result from severing interhemispheric connections in cases where both hemispheres are required for speech production.

Positron emission tomography in two cases of childhood epileptic encephalopathy (Lennox-Gastaut syndrome)

Two patients with childhood epileptic encephalopathy were studied by positron emission tomography before and after corpus callosotomy. Preoperatively, both patients showed in the temporal lobe unilateral hypometabolism that is characteristic of interictal epileptic foci. Postoperatively, the first patient had no seizures by the time of scanning, and his temporal lobe metabolism was bilaterally symmetric. Seizure control in the second patient did not improve by the time of scanning, and unilateral temporal hypometabolism persisted. This finding suggests a temporal lobe focus in two patients with Lennox-Gastaut syndrome.

A direct hepatotoxic effect of valproic acid

Nine patients treated with valproic acid had low plasma fibrinogen concentration and other liver function abnormalities. Several patients also had a low platelet count and prolonged bleeding time. The abnormal values returned promptly to normal when the drug therapy was discontinued or the dosage reduced. The liver function abnormalities are consistent with a direct, dose-related hepatotoxicity.