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Other Agents
Huperzine A
This agent is not currently US-FDA approved for the prevention or treatment of AD.
Proposed
Mechanism of Action in AD
An alkaloid derived
from the Chinese club moss Huperzia serrata, a traditional Chinese herbal
remedy for fever, inflammation and dementia used for centuries. The compound
exhibits central and peripheral reversible inhibition of acetylcholinesterase26.
The compound appears to inhibit acetylcholinesterase in the frontal cortex,
hippocampus, hypothalamus and striatum. The potency of huperzine A was found
to be 8 times greater than donepezil and 64 times greater than tacrine27.
Huperzine A is currently approved for AD treatment in China and is sold in the
USA as a nutritional supplement.
What
is the Evidence?
The largest trial to date of huperzine A in the treatment in AD was published
in 1995. An 8-week, randomized, double-blind placebo controlled trial compared
huperzine A 200mcg bid to placebo in 103 patients with AD. Of the 50 huperzine
A treated patients, 29 (58%) showed significant improvement (p<0.01) over
baseline in memory, cognition and behavioral measures as compared to 19 (36%)
of the placebo group28.
Patients in the active treatment group were reported to have a mean 3 point
improvement on the MMSE as compared to a 0.4point increase in the placebo-treated
patients.
Most Common Adverse
Effects
Nausea, vomiting, and diarrhea are the most common adverse effects. In the previously
cited study, decrease in baseline heart rate was noted in the active treatment
group — mean heart rate at baseline=72bpm which decreased to a mean of
47bpm.
Patients who utilize huperzine A should be cautioned to monitor
for bradycardia, particularly with concurrent use of medications
which slow heart rate such as beta blockers. Huperzine A should
not be combined with other inhibitors of acetylcholinesterase
such as tacrine, donepezil, or rivastigmine.
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