Smoking might be the most common way to get high, but apparently it’s not the best —at least for medicinal purposes. As Vice puts it, “…taking it up the butt is actually much more effective than smoking it.” Talk of rectal marijuana hit the news cycle following a story in the National Post about Canadian healthcare professionals seeking safer ways to toke up.
Mikhail Kogan, M.D. and medical director of the Center for Integrative Medicine at George Washington University in Washington, D.C. , claims that smoking is an archaic way of getting high, reports the Post. “Rectally is actually a lot more preferred because of the volume of absorption,” he explains. “You can put a lot more and it gets absorbed a lot better, but not everybody is open to this way of administration.” Under the tongue is also more effective than a simple smoke for medical purposes. For those who prefer to eat their weed via savory edibles, he offered this claim: Gastric acids can apparently interfere with absorption. Still, Kogan conceded that “the majority of people” probably still opt for smoking.
“For medical reasons we never use smoking,” he tells Medical Daily. “Most people use vaporized. I mostly use buccal,” the doctor reveals of his preferred method of placing cannabis inside the mouth. Kogan confirms that while more effective than the widely used inhalation method, rectally given marijuana is the least utilized, in part because of the yuck factor. Another reason? There isn’t one set of rules and available forms vary by state. In fact, Kogan isn’t even sure that suppository cannabis is available in D.C. where he practices.
What is the science behind rectal use of cannabis?
According to Allan Frankel, MD, who has researched and written about rectal absorption of cannabis, nothing was felt by his test patients when they tried cannabis oil in cocoa butter. Analysis of their plasma revealed negligible THC and CBD levels. According to Practical Pharmaceutics: An International Guideline for the Preparation, Care and Use of Medicinal Products, the rectum does not absorb fats efficiently. Any active substance in a suppository must first dissolve into the aqueous mucus that lines the rectum and then pass into the bloodstream; it cannot be absorbed directly by the membrane without traversing the aqueous mucus layer. Therefore active substances that are themselves lipophilic (such as cannabinoids) should not be combined with a fatty or oily carrier, as this will reduce their overall absorption. Since virtually every cannabis suppository I found mentioned online was in a fatty base (as was mine), this should have impaired their efficacy.
So, it doesn’t look like weed suppositories will become mainstream anytime soon. However, Kogan is excited about new medical marijuana advancemets, particularly topical and ophthalmic forms, the latter of which he believes will greatly help glaucoma patients.
Assuming that some of the cannabinoid content makes it through the mucus, it then circulates either via the inferior and middle rectal veins into the inferior vena cava, bypassing the liver; or via the superior rectal vein to the liver where it is ‘first pass’ metabolized. It was thought that the lack of psychoactivity resulted from THC missing the liver and therefore not metabolizing into 11 hydroxy delta-9 THC (11-OH-THC) which is more potent, and stays in the system for longer. (Interestingly, the effect of many drugs is reduced by first pass metabolism, but not THC!) Large amounts of 11-OH-THC are produced when cannabis is eaten, so this metabolic process determines much of the strength of the same dose when ingested in different ways.
The most recent scientific research on the rectal absorption of THC was published in 1991, and used crab-eating macaque monkeys. (If you have just thought to yourself “poor monkeys!”… Have you seen what else they do to monkeys? These monkeys are the lucky ones.) Results showed no rectal bioavailability of THC, but when the cannabinoid was processed to create a combination with the molecule ester hemisuccinate (THC-HS), the bioavailability shot up to 13.5% and the mean residence time of THC in the blood was 5.8 hours. THC-HS is water-soluble, which is why it dissolves into the aqueous mucus.
It might be possible that the effect is long-lasting because any THC missing the first pass when it initially entered the bloodstream via the inferior and middle rectal veins would eventually reach the liver, so a second phase of metabolism into 11-OH-THC could take place long after the initial dose.
However, for the THC to get to any of the rectal veins, it still needs to traverse the aqueous mucus layer. This shouldn’t be possible without the presence of the hemisuccinate ester. Could it be that some part of the process of making the butane extracted concentrate causes the presence of THC-HS, or a similar enough ester to permit absorption to occur? The experiments on the macaque monkeys used THC only, not whole plant extract. Could the presence of other cannabinoids, the ‘entourage effect’, make the crucial difference? However, Dr Frankel’s studies used cannabis oil in cocoa butter, and that did not seem to work. The doctor himself concludes that more research is needed in order to take full advantage of this delivery method.