The first step in ensuring its safe and appropriate use is to be aware of the legal and regulatory status of medical marijuana, noted Dr. Holle, an assistant professor in the faculty of pharmacy at the University of Connecticut at Storrs. Twenty-five states, in addition to Washington DC and Guam, have legalized medical marijuana for conditions and diseases that vary from state to state. Cancer is one of the conditions included in all of them, but the evidence is limited. (A 1970 federal law that classifies marijuana as an illegal drug – Class I – makes it extremely difficult to investigate cannabis use)
Dr. Holle’s state, Connecticut, is one of three that require the presence of a pharmacist at the medical marijuana dispensary; Minnesota and New York are the other two. As for how it is prescribed-not actually prescribed: “Doctors cannot prescribe marijuana because it is a Class I drug,” he explained. “They can only certify that they have approved a patient to use it.” If a patient has cancer, he or she can receive marijuana, and certifiers do not need to specify whether it will be used for pain or another side effect, he added. Certified patients receive a medical marijuana card that they can take to a dispensary, and most patients will be certified to receive the state’s maximum allowable amount.
Dr. Holle said she has several cancer patients who successfully use medical marijuana under these conditions, and works with pharmacists who dispense it to ensure that patients know how to access it and are being properly monitored.
“I have patients who would never have expected that they might want to try medical marijuana,” said Dr. Holle. “I had an elderly patient with pancreatic cancer who survived much longer than we expected; the patient used vaporized medical marijuana and said her life was amazing and she was pain free. ”
The Case of Cannabis
Although anecdotal evidence is compelling, one of the important keys to managing medical marijuana patients is having a great working knowledge of the history and science behind its use, as well as objective evidence of this controversial indication, Dr. Holle noted.
Marijuana has been used in medicine since 1800. California became the first state to legalize it for medicinal use in 1996. It was first approved for AIDS and cancer patients, and then expanded to other conditions.
The medical benefits of marijuana come from the cannabinoids produced by the Cannabis Sativa and Indica species. More than 80 different cannabinoids have been identified, and it is thought that the most important for their medicinal effects are δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) (CA Cáncer J Clin 2015; 65 : 109- 122).
Different strains of marijuana contain different levels of THC and CBD, and dispensaries recommend specific strains depending on the effect (anti-pain, etc.) that the patient needs. Medical marijuana is mainly smoked, consumed in vaporized form or orally in the form of crackers, biscuits, other baked goods, etc. Other routes of administration are intrathecal, intravenous, ophthalmic, transdermal, sublingual or rectal. Dr. Holle noted that marijuana does not contain nicotine, but when smoked, it does contain carcinogens, so pharmacists can guide patients toward different routes of administration than smoking, such as vaporization or edible marijuana.
The effects of inhaled marijuana usually wear off in an hour, while those of orally consumed marijuana generally last two to three hours, but can last up to six hours (Table 1). By inhalation, potency depends on how deeply a person inhales it and for how long.
Table: Pharmacological parameters of inhaled and oral marijuana
|Time to obtain maximum concentration||1-6 hours||2-10 minutes|
|Maximum duration||2-3 hours||Depends on the dose, to get the maximum psychotropic effect, 20 minutes, with a sudden drop that lasts 45-60 minutes|
|Distribution||–||90% plasma; it is linked to protein in 10% of red blood cells and in 1% of the brain. It crosses the placenta and is detected in breast milk|
The Evidence in Cancer Cancer
patients use medical marijuana for chemotherapy-induced pain, nausea, and vomiting (CINV), as well as appetite, sleep, and mood. Most of the data on marijuana and cancer comes from synthetic cannabinoids currently on the market. Dronabinol (Marinol, Abbvie) is approved for refractory CINV and AIDS weight loss / anorexia. Nabilone (Cesamet, Meda) is approved for refractory CINV. A third synthetic cannabinoid, Sativex (Sativex, GW), is available in 15 countries and is expected to gain approval in the United States in the near future. “There are quite a few studies with synthetic marijuana,” said Dr. Holle.
“The bottom line is that they appear to be effective, especially in moderately emetogenic regimens.”
A few small clinical trials have shown that cannabis smoked or taken orally can reduce CINV symptoms by between 80% and 93%, and is as effective as phenothiazine (Table 2). Dr. Holle notes that the type of strains and route of administration affect the results, but most of the available data do not capture this information. Marijuana is not recommended as an option in CINV guidelines, but is used for refractory or advanced CINV, Dr. Holle noted. “Anecdotally, there are patients who have had good results, even when they tried newer antiemetics,” she said.