Huperzine A

Huperzine A May Be Useful In Treating Alzheimer’s Disease

Scientific Name: Huperzine A

Other Names: Chinese Club Moss, Hup A, Huperzia serrata, Lycopodium serrata, Qian Ceng Ta, Shuangyiping

Uses

In traditional Chinese medicine, a particular type of club moss identified as “qian ceng ta” in China or “Chinese club moss” in other parts of the world, has been used for centuries to treat inflammation and fever. While no scientific evidence supports these historical uses, Chinese club moss plants are known to contain chemicals that may promote the loss of water from the body. The resulting mild diuretic action may help to reduce swelling due to water retention.

During the past few years, huperzine A, an alkaloid in Chinese club moss, has been studied extensively for its potential in treating dementias such as Alzheimer’s disease. Dementia is an increasing deficiency in thought processes caused by brain damage, disease, or exposure to chemicals. Alkaloids are plant compounds that contain nitrogen. They usually taste bitter and many of them have medical properties. Like the prescription drugs currently available for individuals with Alzheimer's, uperzine A temporarily blocks an enzyme known as acetylcholinesterase, which is concentrated in the brain, spinal cord, and red blood cells. This enzyme, also called cholinesterase, breaks down one of the body's neurotransmitters, acetylcholine. Neurotransmitters are chemicals that carry messages from nerve cells to other cells. Acetylcholine plays a role in learning, remembering, and thinking; and decreased amounts of it are associated with conditions involving the loss of mental functioning. By reducing the activity of acetylcholinesterase, huperzine A may help to reduce the breakdown of acetylcholine, keeping more of it the blood. Frequently called a "cholinergic" effect, the increase in acetylcholine may help preserve or even restore memory. Several studies of memory-impaired animals and humans have shown that taking huperzine A may help to relieve dementia. Additionally, in a small study of teenagers, huperzine A appeared to enhance general mental functioning when it was taken consistently for as little as one month. However, more research is needed before huperzine A can be recommended for either dementia or general memory improvement.

Results from another small human study showed that huperzine A may also improve symptoms of myasthenia gravis, a rare but serious autoimmune condition. In myasthenia gravis, the body produces antibodies that deactivate acetylcholine receptors on muscle cells. Progressive muscle weakness develops—eventually resulting in paralysis and respiratory failure. By decreasing the amounts of acetylcholinesterase, which increases available acetylcholine, huperzine A may allow the remaining acetylcholine receptors to function more effectively. The deterioration of muscle function may be delayed or stopped. Additional studies are underway to prove or disprove this possible use of huperzine A. Huperzine A also shows promise in the prevention of poisoning from a class of chemicals called organophosphates. Often used as pesticides or in chemical "nerve gas" weapons, these chemicals work by suppressing acetylcholinesterase permanently. Unlike the Alzheimer's disease treatments that reduce cetylcholinesterase for relatively short lengths of time, organophosphates virtually eliminate its activity. As a result, nerve signals to muscles are not interrupted and seizures result. Death may result from uncontrollable seizures or from spasms of the muscles that control breathing. In several studies of laboratory animals, small but constant doses of huperzine A given before exposure to organophosphates prevented seizures and protected nerve tissue from damage. No human studies have been conducted to confirm these results. When should I be careful taking it?

Because huperzine A may increase the likelihood of seizures for individuals with epilepsy, it should not be taken by individuals who have or who ever have had seizures. Huperzine A may cause the heart to beat slower than it would normally. Individuals who have heart rhythm abnormalities should avoid taking huperzine A due to the chance it may cause dangerous disruptions in heart rhythm.

One side effect of increased acetylcholine activity (cholinergic effects) is an increase in body secretions, including mucus and saliva. This effect may worsen respiratory conditions such as asthma, bronchitis, and emphysema. Individuals with chronic respiratory conditions should not take huperzine A because of its cholinergic effects. Increased production of stomach acid, possibly caused by huperzine A's cholinergic effect, may aggravate ulcers of the stomach or small intestine. Therefore, individuals with gastrointestinal ulcers should avoid taking huperzine A.

Urine output may also be increased by huperzine A. Individuals who have bladder conditions or other conditions, such as benign prostate hyperplasia (BPH), that may be made worse by increased amounts of urine should not take huperzine A.

Precautions

Very little information is available on how huperzine A might affect a developing fetus, an infant, or a small child. Therefore, its use is not recommended during pregnancy, while breast-feeding, or during early childhood.

Side Effects

Major Side Effects:

Huperzine A may increase the risk of having seizures for individuals who have or who have had epilepsy.

Potentially dangerous changes in heart rhythm may be caused by using huperzine A.

Less Severe Side Effects:

Other side effects that may be attributed to the use of huperzine A include:

Blurry vision

Diarrhea

Dizziness

Drooling

Nausea

Slowed heartbeat

Stomach cramps

Sweating

Interactions

Some prescription drugs inhibit acetylcholine. These "anticholinergic" drugs are sometimes used to prevent bed wetting, relieve stomach cramps, and treat nausea. If huperzine A is taken at the same time as an anticholinergic drug the effects of both it and the drug may be lessened to unpredictable extents.

Anticholinergic drugs include:

atropine

dicyclomine (Bentyl)

glycopyrrolate

Levsin

propantheline

Both the effects and the risk of side effects may be increased if huperzine A is taken at the same time as a prescription drug that also reduces acetylcholinesterase activity. In addition to Aricept and Cognex, which are used to treat Alzheimer's disease, "cholinergic" drugs include pyridostigmine (Mestinon) and neostigmine, which may be used to treat myasthenia gravis; and bethanechol (Urecholine), which may be used for the treatment of urine retention.

Some interactions between herbal products and medications can be more severe than others. The best way for you to avoid harmful interactions is to tell your doctor and/or pharmacist what medications you are currently taking, including any over-the-counter products, vitamins, and herbals. For specific information on how huperzine A interacts with drugs, other herbals, and foods and the severity of those interactions, please use our Drug Interactions Checker to check for possible interactions.

Should I take it?

Huperzine A is one of the alkaloids contained in a plant known as Chinese club moss. Believed to be largely unchanged from prehistoric plants, club mosses are small ground covers that do not produce flowers. Related to the fern family of plants, they spread by sending out spores instead of seeds. They thrive in damp, shaded areas such as tropical woodlands and the edges of swamps. As its name suggests, Chinese club moss mainly is found in China and other parts of Asia, where it grows wild. Much of the research on huperzine and other components of Chinese club moss has been conducted in oriental countries. Other types of club moss are common in the United States, but true Chinese club moss is very hard to find on the U.S. market. It can be grown in Hawaii, but not in any other part of this country. Because demand for it is so high, ways to cultivate Chinese club moss commercially are being researched.

Huperzine A and huperzine B are two of the chemicals that have been separated from Chinese club moss. Huperzine B is also an acetylcholinesterase inhibitor, but because its effects are much weaker than those of huperzine A, it has not been studied as much. Synthetic forms of huperzine A have been made in chemical laboratories and they appear to be as effective as natural huperzine A in studies. Huperzine A has also been combined or “hybridized” with the prescription drug tacrine (Cognex), an acetylcholinesterase inhibitor approved by the U.S. Food and Drug Administration for treating Alzheimer’s disease. The resulting “huprine” combination seems to be more effective at limiting acetylcholinesterase activity than either agent alone. It is not available for general use, however. Much more study needs to be done on the possible effects of huperzine A, huperzine B, huprine, and other chemicals derived from Chinese club moss before they can be recommended for any condition.

Dosage and Administration

Note: Alzheimer's disease and myasthenia gravis are very serious conditions that require the attention of a healthcare professional. They should not be self-treated. Neither huperzine A nor any other herbal or over-the-counter medication is sufficient treatment. Additionally, much of the research on huperzine A has used an injectable form, which is mainly available in Asian countries.

Huperzine A is marketed in a number of oral dosage forms—mainly capsules, extracts, or tablets. In studies of individuals with Alzheimer’s disease or similar conditions, daily oral doses ranged from 60 micrograms to 400 micrograms, usually taken in two doses. Individuals who decide to use a huperzine A product should follow the directions on the package that is bought.

Huperzine A injected in doses of 400 micrograms per day has been used to treat myasthenia gravis, but injectable huperzine A is not available in the United States. A doctor should supervise any individual using injectable huperzine A.

Summary

Huperzine A may be used to treat dementia, memory loss, and other cognitive deficiencies. It may also be helpful for individuals with myasthenia gravis and it may protect against poisoning with organophosphate chemicals.

Risks

Epileptic seizures or heart rhythm changes may be caused or worsened by taking huperzine A. It may also worsen asthma, bladder conditions, BPH, bronchitis, emphysema, or ulcers. Not enough is known about huperzine A to recommend it for pregnant or breast-feeding women or young children.

Side Effects

Huperzine A may cause seizures or heart rhythm changes. It may also be associated with blurred vision, dizziness, nausea, and increased saliva and sweat.

Interactions

Huperzine A may counteract the effects of drugs — such as dicyclomine, Levsin, and propantheline — that are used to decrease acetylcholine's effects. On the other hand, it may increase the acetylcholine-enhancing effects of drugs such as Aricept and Cognex.

Last Revised August 22, 2007

Last Revised August 22, 2007

Note: In general, herbal products are not subject to review or approval by the U.S. Food and Drug Administration (FDA). They are not required to be standardized, meaning that the amounts of active ingredients or contaminants they contain may vary between brands or between different batches of the same brand. Not all of the risks, side effects, or interactions associated with the use of herbal products are known because few reliable studies of their use in humans have been done.