A multicenter double-blind study of controlled-release physostigmine for the treatment of symptoms secondary to Alzheimer's disease. Physostigmine Study Group. Double-blind, randomized, placebo-controlled clinical trial on the efficacy and tolerability of a physostigmine patch in patients with senile dementia of the Alzheimer type. A 24-week randomized trial of controlled-release physostigmine in patients with Alzheimer's disease. Extended-release physostigmine in Alzheimer disease: a multicenter, double-blind, 12-week study with dose enrichment. Physostigmine Study Group. Clinical pharmacokinetics of physostigmine in patients with Alzheimer's disease. The effect of long-term physostigmine administration in Alzheimer's disease. Oral physostigmine as treatment for primary degenerative dementia: a double-blind placebo-controlled inpatient trial. Efficacy of oral physostigmine in primary degenerative dementia. A double-blind study of response to different dose level. Enhancement of memory processes in Alzheimer's disease with multiple-dose intravenous physostigmine.
A multicenter trial to evaluate the efficacy of controlled-release physostigmine salicylate, a cholinesterase inhibitor, was conducted in 1,111 mild-to-moderate Alzheimer's disease (AD) subjects.
                During dose titration, subjects received 18, 24, or 30 mg of physostigmine or placebo daily. After a 2-week washout period, 366 subjects with putative improvement were randomized to receive either placebo or their best dose of physostigmine in a 6-week double-blind trial. Nonresponding patients (439) were randomized to receive in a separate double-blind trial either placebo or their highest tolerated dose of physostigmine. The primary efficacy measures included the cognitive subscale of the Alzheimer Disease Assessment Scale (ADAS) and a Clinical Global Impression of Change (CGIC). Secondary measures included the Mini-Mental State Examination and two activities-of-daily-living scales.
                At the end of the 6-week double-blind phase, physostigmine-treated patients scored 1.75 points higher than placebo-treated patients on the ADAS (p = 0.003) and 0.26 points higher on the CGIC (p = 0.012) in the intent-to-treat analysis. There was no significant improvement on the secondary outcome measures. Patients failing to respond to physostigmine during the dose titration phase failed to respond on any of the outcome measures during the double-blind period of re-exposure. Common adverse events included nausea, vomiting, diarrhea, and anorexia. There were no significant changes in liver function tests.
                This study demonstrated statistically significant differences between physostigmine and placebo on both a performance-based cognitive functioning instrument and a clinician's global evaluation. The magnitude of the effect size was small and occurred only in the subset of patients who responded in the initial dose titration study period. Nevertheless, the results suggest that in a subset of patients, physostigmine can induce a degree of cognitive improvement over 6 weeks of treatment. Owing to the pharmacokinetic properties of physostigmine when administered by conventional routes, long-term cholinergic treatment of Alzheimer's disease is difficult to manage. In order to overcome the problems associated with the oral and intravenous application of physostigmine, and to improve patients' compliance, a transdermal therapeutic system was developed. The efficacy and tolerability of this system were evaluated in a double-blind, randomized, multicenter study comparing patches containing 30 mg and 60 mg physostigmine with a placebo patch. The clinical trial followed the basic principles of the various guidelines on the evaluation of anti-dementia drugs, and included patients with mild to moderate probable Alzheimer's disease. A total of 204 patients with probable Alzheimer's disease were included in the study. Of these, 136 patients were eligible for the according-to-protocol analysis of efficacy, 167 subjects for the intention-to-treat analysis of efficacy, and 181 patients were included in the safety analysis. In contrast to the hypothesis to be tested, the efficacy of physostigmine was not superior to that of placebo after a treatment period of 24 weeks. On the contrary, there was even a slight, but not statistically significant, trend toward a better outcome in the placebo group. Median physostigmine plasma concentrations of approximately 100 pg/ml were measured, showing a high degree of interindividual variability and no linear dose relationship between the 30 mg and 60 mg dosages. Plasma cholinesterase activity was not significantly affected by physostigmine. The physostigmine patch application in doses of 30 mg and 60 mg apparently did not lead to physostigmine plasma concentrations that were sufficient to compensate for cholinergic deficiencies in affected brain areas and produce clinical benefits. Both the drug and the transdermal system were generally well tolerated under the study conditions. Modifications of the patch system may perhaps make it possible to achieve higher physostigmine plasma concentrations, which seem to be required to induce the expected beneficial effects during long-term treatment of Alzheimer's disease. To evaluate the safety and efficacy of controlled-release physostigmine, an acetylcholinesterase inhibitor, in patients with probable AD of mild to moderate severity.
                A prospective, 24-week, randomized, multicenter, double-blind, parallel group study of patients was conducted. The study enrolled 475 patients at 24 sites. Patients met criteria for probable AD and were randomized to one of three arms: placebo, controlled-release (CR) physostigmine 30 mg daily, or CR physostigmine 36 mg daily. Dosage was escalated by a forced upward titration during the first 6 to 9 weeks of the trial, then maintained at a constant dose to 24 weeks. Primary outcome measures were the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) and the Clinician's Interview-Based Impression of Change-Plus with caregiver input (CIBIC+). Secondary outcome measures included the Clinical Global Impression of Change (CGIC), the Geriatric Evaluation by Relatives Rating Instrument, and an Instrumental Activities of Daily Living Scale.
                In an intent-to-treat population, the last observation carried forward analysis revealed a 2.9-point ADAS-Cog (p = 0.002) difference between physostigmine and placebo-treated patients for both dosages, and a 0.26 to 0.31-point difference on the CIBIC+ (p = 0.048). There were no significant differences on the secondary outcome measures except for a difference on the CGIC when analyzed by use of the Cochran-Mantel-Haenszel statistic (p = 0.014). There were significant increases in gastrointestinal side effects including nausea, vomiting, diarrhea, anorexia, dyspepsia, and abdominal pain for patients on either dose of physostigmine, resulting in a high dropout rate. Agitation was decreased significantly. There was no evidence of cardiac rhythm disturbance or liver function abnormalities.
                CR physostigmine enhanced cognitive and global function. It is relatively safe for the treatment of cognitive dysfunction secondary to AD. However, in light of the gastrointestinal side effects, a lower starting dose and a flexible titration schedule might lead to a more favorable adverse event profile in the clinical arena. The efficacy of extended-release physostigmine salicylate, an acetylcholinesterase inhibitor, was evaluated in 850 subjects with mild-to-moderate Alzheimer disease (AD) in a multicenter trial.
                Subjects initially entered a dose-enrichment phase in which they received 1 week each of physostigmine salicylate, 24 mg/d and 30 mg/d, and daily placebo. Among the subjects who completed this phase, 35.9% responded to physostigmine treatment, whereas 62.4% were considered nonresponders, and 1.6% could not be evaluated because of missing data. After a 4-week placebo-washout phase, 176 responder subjects were randomized to receive their best dose of physostigmine or placebo in a 12-week double-blind phase. Primary efficacy measures included the cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-Cog), the Clinician's Interview-Based Impression of Change With Caregiver Input (CIBIC+), and the Clinical Global Impression of Change (CGIC).
                In the intent-to-treat analysis of the double-blind phase, physostigmine-treated subjects scored -2.02 points better than placebo-treated subjects on the ADAS-Cog (F1,167 = 6.42 [P = .01]) and 0.33 points higher on the CIBIC+ (F1,150 = 5.68 [P = .02]). No significant improvement was observed on the CGIC or the secondary outcome measures. Nausea and vomiting were experienced by 47.0% of all physostigmine-treated subjects during the double-blind phase.
                Physostigmine demonstrated a statistically significant benefit compared with placebo on a clinical global rating of change and an objective test of cognitive function. Given the frequency of gastrointestinal side effects, the role of this agent in clinical use remains to be determined. To study the pharmacokinetic and pharmacodynamic properties of physostigmine in subjects with Alzheimer's disease.
                Plasma physostigmine concentration and butyrylcholinesterase inhibition were measured in blood samples collected during and after a single high-dose (1 to 1.5 mg for 45 to 60 minutes) and a sustained low-dose steady-state intravenous infusion in nine subjects with Alzheimer's disease. Escalating doses (0.5 to 25 mg/day) were administered during a 2-week period. A dose (2 to 12 mg/day) that optimized cognition in each subject was identified and then administered in a randomized, double-blind, placebo-controlled crossover design for 1 week.
                The elimination half-life of physostigmine was 16.4 +/- 3.2 (SE) minutes. Clearance and volume of distribution were 7.7 +/- 0.9 (SE) L/min and 2.4 +/- 0.6 (SE) L/kg, respectively. Butyrylcholinesterase inhibition half-life was 83.7 +/- 5.2 (SE) minutes. During sustained steady-state infusion, plasma physostigmine concentration (r = 0.95) and butyrylcholinesterase inhibition (r = 0.99) were linearly correlated with the dose. In five cognitive responders, the memory enhancement was significantly correlated (r = 0.86; p < 0.05) with butyrylcholinesterase inhibition.
                These results showed that, in cognitive responders, memory enhancement by physostigmine in Alzheimer's disease is correlated directly to the magnitude of plasma cholinesterase inhibition. Furthermore, during single-dose conditions, the dynamic half-life is five-fold longer than the kinetic half-life. We assessed the effect of chronic long-term physostigmine in 20 patients with probable Alzheimer's disease. Initially, all patients went through a dose-finding phase and a double-blind crossover period, and were subsequently classified as physostigmine responders or nonresponders based on an a priori classification system. We then offered all patients long-term treatment with physostigmine regardless of their initial classification. Results revealed that responders spent significantly (p less than 0.0005) longer time periods on drug (36.1 +/- 4.6 months) than nonresponders (10.8 +/- 3.2). During a 2nd crossover period, 18 months into treatment, responders still demonstrated behavioral improvement, as assessed with the Sandoz Clinical Assessment-Geriatric Scale, whereas there were no behavioral changes observed in nonresponders. There were no effects on formal neuropsychological assessment. The results suggest that a subgroup of Alzheimer's patients benefits from long-term physostigmine therapy. Twenty-three patients with primary degenerative dementia (Alzheimer's disease) were administered an optimal dose of oral physostigmine and placebo, each for a 1-week period, under double-blind conditions on a research unit of a general hospital. Each patient served as his or her own control. The optimal dose of physostigmine for each patient was determined previously by a dose-finding phase. There were no significant group differences on a number of neuropsychological tests. Along with other studies in the literature, this study casts serious doubt on the efficacy of short-term administration of oral physostigmine when used alone in an attempt to ameliorate cognitive dysfunction in Alzheimer's disease patients. The possibilities that physostigmine may slow the course of the disease or may acutely improve symptoms when combined with other agents are discussed. To examine the efficacy of cholinergic enhancement in senile dementia of the Alzheimer type (SDAT), oral physostigmine was given to eight patients in a cross-over trial of three dose levels and a matching placebo. A dose-related improvement in memory as measured by objective verbal memory tests was observed. Performance was significantly better on the highest dose, 2 mg every 2 h, than on the lower doses. The effect was most systematically present for very short-term memory, which raises the question of whether the improvement may involve attention rather than longer term storage and retrieval. Physostigmine (.125 mg, .25 mg, or .50 mg) or placebo was administered intravenously to 10 neuroleptic-free patients with Alzheimer's disease over a 30-minute period. All patients performed better on a recognition memory task while receiving physostigmine. When placebo or the dose of physostigmine previously associated with an improvement in memory was readministered, physostigmine again enhanced performance on a recognition memory task. These results indicate that the acute augmentation of cholinergic activity in some patients with Alzheimer's disease can partially reverse the memory deficit of that disorder and may provide an approach to the eventual therapy of this condition.
The evidence of effectiveness of physostigmine for the symptomatic treatment of Alzheimer's disease is limited. Even in a controlled release formulation designed to overcome the short half-life, physostigmine showed no convincing benefit and adverse effects remained common leading to a high rate of withdrawal.