title: Efficacy and safety of a loading-dose regimen versus a no-loading-dose regimen of metrifonate in the symptomatic treatment of Alzheimer's disease: a randomized, double-masked, placebo-controlled trial. Metrifonate Study Group.
abstract: This prospective, randomized, double-masked, placebo-controlled, parallel-group study assessed the safety and efficacy of 2 dosage regimens of once-daily metrifonate in patients with probable Alzheimer's disease (AD) of mild-to-moderate severity. A total of 395 patients were randomized to receive placebo (n = 134) or metrifonate in 1 of 2 regimens. The loading-dose group (n = 133) received a daily loading dose of metrifonate 100 mg or 150 mg (by weight) for 2 weeks, followed by a daily maintenance dose of metrifonate 50 mg for 4 weeks; the no-loading-dose group (n = 128) received the daily maintenance dose of metrifonate 50 mg for 6 weeks. The primary measure of efficacy was the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog); secondary measures of efficacy included the Mini-Mental State Examination (MMSE), the Clinician's Interview Based Impression of Change with Caregiver Input (CIBIC-Plus), the Clinician's Interview Based Impression of Severity with Caregiver Input (CIBIS-Plus), and the ADAS-Noncognitive Subscale (ADAS-Noncog). Safety was assessed by the prevalence of premature study termination and treatment-emergent adverse events, as well as by changes in vital signs, findings on electrocardiographic and neurologic examinations, and abnormalities on laboratory tests. At 4 weeks of treatment, defined by the protocol as the target efficacy determination, the mean ADAS-Cog scores of the intent-to-treat population (last observation carried forward) favored the loading-dose group versus the placebo group, but the difference was not statistically significant. However, at week 6, the difference in mean ADAS-Cog scores was statistically significant compared with placebo. At neither week 4 nor week 6 was there a statistically significant difference in the mean ADAS-Cog scores of the no-loading-dose and placebo groups. For the CIBIC-Plus, the treatment difference between the placebo and loading-dose groups significantly favored metrifonate at week 6 but not at week 4, whereas the treatment difference between the placebo and no-loading-dose groups was statistically significant at both time points. For the MMSE, CIBIS-Plus, and ADAS-Noncog, treatment differences for both groups versus placebo did not reach statistical significance at either week 4 or 6. Assessment of the frequency of adverse events in metrifonate-treated patients revealed that the no-loading-dose regimen was better tolerated than the loading-dose regimen. Given the overall similar efficacy and more favorable safety profile associated with the no-loading-dose regimen versus the loading-dose regimen observed in this study, the no-loading-dose regimen appears to be the better strategy for initiating metrifonate treatment in patients with probable AD of mild-to-moderate severity.
authors: Center for Clinical Research, Southern School of Pharmacy, Mercer University, Atlanta, Georgia 30341-4155, USA.
authors: M W
authors: MW
authors: Jann
authors: P A
authors: PA
authors: Cyrus
authors: L S
authors: LS
authors: Eisner
authors: D I
authors: DI
authors: Margolin
authors: T
authors: T
authors: Griffin
authors: B
authors: B
authors: Gulanski
mesh_terms: D000110:Acetylcholinesterase / Q000097:blood; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy*; D002800:Cholinesterase Inhibitors / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004912:Erythrocytes / Q000201:enzymology; D005260:Female; D006801:Humans; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D011446:Prospective Studies; D014236:Trichlorfon / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use
chemical_list: D002800:Cholinesterase Inhibitors; D014236:Trichlorfon; D000110:Acetylcholinesterase