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Tacrine for Alzheimer's disease
N Qizilbash1, J Birks, J López-Arrieta
1SmithKline Beecham, New Frontiers Science Park (South), Third Avenue, Harlow, UK, CM19 5AW. Nawab_Qizilbash-1@sbphrd.com
The Cochrane Database of Systematic Reviews
|May 5, 2000
Summary
This review found no convincing evidence that tacrine effectively treats Alzheimer's disease symptoms. Tacrine showed no significant benefit over placebo and was associated with adverse events, necessitating further data evaluation.
Area of Science:
- Neuroscience
- Pharmacology
- Gerontology
Background:
- Tacrine was an early Alzheimer's disease (AD) drug, but its efficacy remains debated.
- Controversy stems from small effect sizes, adverse events, and methodological issues in clinical trials.
Purpose of the Study:
- To determine the clinical efficacy of tacrine for Alzheimer's disease symptoms.
Main Methods:
- Searched the Cochrane Dementia Group Register of Clinical Trials for randomized trials of tacrine versus placebo.
- Included unconfounded, double-blind trials lasting over one day.
- Extracted data independently, pooled results where possible using intention-to-treat analysis.
Main Results:
- No clear results; tacrine's effects ranged from improvement to harm.
- No significant difference between tacrine and placebo for overall clinical improvement or behavioral disturbance.
- Cognitive function showed no significant difference on the Mini-Mental State Examination, but a slight benefit on the ADAS-cog scale.
- Tacrine withdrawal was significantly higher due to adverse events, particularly elevated liver enzymes and gastrointestinal issues.
Conclusions:
- No convincing evidence supports tacrine as a useful Alzheimer's disease treatment.
- Results may change with access to all trial data.
- Urgent need for independent evaluation of existing, inaccessible trial data.