Posts Tagged pharmacognosy

Medical marijuana as the new herbalism, part 4: Cannabis for autism

Medical marijuana as the new herbalism, part 4: Cannabis for autism

When I first started writing about the claims made for medical marijuana and the cannabis oil derived from it, it didn’t take long for me to characterize medical claims for cannabis as the “new herbalism,” as opposed to pharmacognosy, the branch of pharmacology devoted to the study of natural products. The reason is simple. Although I support legalization of marijuana for recreational use, when I look at how medical marijuana has been promoted as a “foot-in-the-door” prelude to legalization, I see testimonials and flimsy evidence ruling over all. I see all the hallmarks of alternative medicine herbalism and none of the hallmarks of pharmacology. Here’s what I mean. Pharmacognosy examines an herb, plant, or other natural product and seeks to identify the chemicals within it that have pharmacological activity against a condition or a disease, the better to purify and isolate those chemicals and turn them into drugs. Herbalism, on the other hand, emphasizes the use of whole plants or extracts from plants, rather than the isolation of the most active compounds. Thus, herbal remedies often contain hundreds, or even thousands, of different compounds, of which only one or a few are active. Even extracts, such as cannabis oil, contain many compounds.

In contrast to pharmacognosy, herbalists make the claim that whole herbs and plant components possess a synergy that is missing from the purified active constituents and/or that the mixture is safer than the pure components because one compound can reduce the side effects of another without reducing therapeutic efficacy. When looked at closely neither claim stands up to scrutiny. Synergism between plant constituents is rare and very difficult to demonstrate, for example. In essence, herbalism turns back the clock 200 years to a time before scientists had developed the techniques and abilities to isolate active ingredients with pharmaceutical activity. Moreover, herbalism, in contrast to pharmacognosy, emphasizes anecdotes over scientific evidence.

Indeed, in my previous posts in this series on medical marijuana, one theme has emerged, which is that cannabis—specifically, a class of active chemicals in marijuana known as cannabinoids—has potential for some diseases but is not the panacea claimed by its proponents. It does not cure cancer, for instance, contrary to glowing testimonials promoted by people like Rick Simpson. For other conditions, the evidence is either not particularly compelling or only mildly promising.

So I reacted with considerable dismay on Friday night when I saw this news report on the 11 o’clock news, “Michigan panel recommends allowing marijuana for autism“:

Posted in: Herbs & Supplements, Politics and Regulation

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Herbal Center at Cleveland Clinic

The infiltration of pseudoscience and simply bad medicine into mainstream medicine continues. Hospitals are an easy breech point because they are run by administrators who may have more talent and interest in marketing than in science. Many hospitals in my area, for example, proudly display their “integrative” centers, offering nutrition advice and massage alongside more dubious offerings, such as reflexology and reiki.

So-called “alternative” treatments are tempting because they are often not covered by insurance, and so patients will have to pay cash for them, and they are often inexpensive to run – so they are a nice cash cow for hospitals.

The Wall Street Journal reports another, more serious, chapter in this infiltration – the opening of Chinese herbal clinics, specifically in the Cleveland Clinic. The article itself is reasonably balanced, and lacks the gushing anecdotes that most such pieces have, but could certainly have been more hard-hitting in terms of the serious problems with herbal medicine.


Posted in: Herbs & Supplements

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Natural is not innocuous: the case of Angel’s Trumpet and tropane alkaloid intoxication

With this post, I’m happy to return to Science-Based Medicine on a regular basis, at least monthly and perhaps more depending upon how often commentary is required on natural products, whether they be herbal medicines or single-agent pharmaceuticals derived from natural sources. Next week, I’ll be attending the 2010 Annual Meeting of the American Society of Pharmacognosy being held jointly with the Phytochemical Society of North America in St. Petersburg, Florida. I hope to bring back the latest on novel natural products in preclinical development.

But today, I bring recent news that revisits a timeworn folly of the young (and some older folks): recreational use of toxic plants for the purpose of hallucination.

Toxicity reports are re-emerging in southern California this week after a dozen hospitalizations of kids using teas made from a fragrant flowering plant called Angel’s Trumpet. The tea is used to produce hallucinations, but they can progress to extremely unpleasant experiences. Moreover, Angel’s Trumpet can be deadly, accelerating the heart rate and causing fatal cardiac rhythmic disturbances and bronchoconstriction that can trigger asthma attacks in sensitive individuals.

220px-Atropine.svg.pngAngel’s Trumpet is one of a series of plants in the Brugmansia genus that make a variety of muscarinic cholinergic antagonists such as atropine (dl-hyoscyamine, pictured to the right) and scopolamine (l-hyoscine). These compounds are also known chemically as tropane alkaloids or belladonna alkaloids, the latter derived from their classical isolation from Atropa belladonna. The belladonna name derives from the use of eye drops made from the plants that prevent constriction of the pupils (mydriasis), back when the size of a woman’s pupils was a sign of beauty and arousal.

The tropane alkaloids are ubiquitous in plants and fungi and act as classic hallucinogens when used in high doses. Their legend goes back to witches brews and beyond. A wonderfully colorful history of tropane alkaloids by Robert S. Holzman of Children’s Hospital and Harvard Medical School was offered in this free 1998 paper in the journal, Anesthesiology (1998; 89:241-249).

However, the aftermath of Angel’s Trumpet use is far from colorful. In cases like these, I like to turn to the Erowid site, a respected, user-supported site that offers non-judgmental information on plant-derived and synthetic psychoactive agents. The Erowid Experience Vault has several descriptions of the use of Angel’s Trumpet but this one is the most detailed and representative of the downsides of this plant. (Note that the colloquial term for Angel’s Trumpet in Australia is sometimes “Tree Datura,” although Brugmansia is a closely-related but distinct genus from Datura within the Solanaceae family.)

I also came across a poorly-documented 2003 news article cited a German teenager cutting off his penis and tongue with garden shears after using Angel’s Trumpet.

While I’m NOT a physician, emergency personnel stumbling upon this post would do well to note that physostigmine or pilocarpine are typical antidotes for anticholinergic poisonings with Angel’s Trumpet, Atropa, Datura, and other similar plants that cause dilated pupils with loss of accommodation, xerostomia (dry mouth), and tachycardia. Click on the link in this paragraph to access the Medscape poisoning article with more details on when and where specific treatments should be employed.

From the eMedicine article linked to in the above paragraph:

Remember common signs and symptoms with the mnemonic, “red as a beet, dry as a bone, blind as a bat, mad as a hatter, and hot as a hare.” The mnemonic refers to the symptoms of flushing, dry skin and mucous membranes, mydriasis with loss of accommodation, altered mental status (AMS), and fever, respectively.

I encourage all clinicians to be vigilant about anticholinergic poisonings in the weeks to come. In some cases in the past, I have found that reports such as these from southern California will often give rise to attempts to use the hallucinatory plant elsewhere despite the risks detailed.

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