What You Need to Know About Medical Marijuana

As of this writing, medical marijuana is legal in 20 states and the District of Columbia, but it is still considered a federal offense to grow, sell, or purchase marijuana. Because of its therapeutic potential, medicinal marijuana is being prescribed by an increasing number of clinicians for various disorders. However, because of the federal criminalization of marijuana, evidence-based research into its effectiveness has been hindered, and many clinicians still question its scientific legitimacy.^1,2

Marijuana, also known as Cannabis sativa, has been used since ancient times for therapeutic, spiritual, and recreational purposes. Clinicians in the United States prescribed marijuana for many different conditions until it was declared illegal and removed from the U.S. Pharmacopeia in 1942.

The Controlled Substance Act of 1970 placed marijuana in the Schedule I category as a substance with high potential for abuse, the same as illicit street drugs.² Although many anecdotal reports and research studies show its therapeutic value for a number of different disorders, the use of medicinal marijuana has been a controversial topic.


Constituents 


The two primary compounds that contribute to marijuana’s therapeutic value are tetrahydrocannabinol (THC) and cannabidiol (CBD). Natural marijuana plants contain 5% to 15% THC, the most active ingredient. The variability in THC-to-CBD ratio in different marijuana plants makes dosage standardization difficult.³

THC, the primary psychoactive component of marijuana, binds to cannabinoid receptors in the brain and produces feelings of euphoria, altered sense of time, analgesia, increased appetite, and impaired memory. CBD is a nonpsychoactive compound that is a serotonin receptor agonist with anti-inflammatory and neuroprotective effects.⁴ 


Pharmacokinetics


The pharmacokinetics of THC vary depending on the route of administration. Medical marijuana can be administered by inhalation or orally. Inhaled THC causes maximum plasma concentration after 15 to 30 minutes, with a duration of two to three hours. Following oral ingestion, effects begin in 30 to 90 minutes and can last up to 12 hours.

The duration of marijuana’s effects depends on dosage; however, it is unclear how to deliver a specific dose of marijuana by smoking.³ Patients report that the inhalation route is the most effective mode of delivery. 


The FDA has approved two oral forms of synthetic THC: dronabinol (Marinol) and nabilone (Cesamet). Patients report that these agents are slow-acting and less effective than inhaled forms of marijuana. Nabiximol (Sativex), an oral mucosal spray, has been approved for medicinal use in Europe only.² 


As a Schedule I drug, the marijuana plant has great potential for abuse and dependence, and use of it is restricted. Nabilone is a Schedule II drug, and dronabinol is a Schedule III drug, which indicate that these medications have less abuse potential, do not usually lead to dependence, and are approved for restricted use.²


Therapeutic uses


Studies show that the most common conditions for which medical marijuana is being prescribed include HIV/AIDS wasting syndrome, cancer chemotherapy, and pain. The American College of Physicians (ACP) recommends medicinal marijuana for the following therapeutic uses:⁵


• As an appetite stimulant in HIV/AIDS wasting syndrome

• As an antiemetic agent in chemotherapy treatment of cancer

• As an analgesic for cancer pain

• As an agent in reducing intraocular pressure in glaucoma (however, there is no increased benefit compared with available established drugs) 

• As an antispasmodic agent in such neuromuscular disorders as multiple sclerosis and spinal cord injury.


Medical marijuana has been shown to be particularly effective in pain management. Marijuana potentiates analgesic effects when used with narcotics, thereby diminishing the dosage of opioids needed for pain relief.⁶

Currently, studies are being conducted to evaluate the use of medical marijuana in rheumatoid arthritis, multiple sclerosis and spinal cord injury, Crohn disease, endometriosis, epilepsy, and fibromyalgia. Marijuana’s anxiety-reducing effects are being studied for use in the treatment of post-traumatic stress disorder.⁷


Adverse effects and safety issues


A significant part of the debate surrounding the use of medical marijuana relates to its possible adverse effects, which include hypotension, sedation, dizziness, decreased reaction time, reduced motor skills, diminished cognitive ability, and impaired memory. Some patients report increased anxiety or paranoia after using inhaled marijuana. Studies have shown increased symptoms of psychosis in patients with schizophrenia after smoking marijuana.² 


The long-term effects of inhaled marijuana on the respiratory system are similar to those associated with chronic obstructive pulmonary disease. Inhaled marijuana is believed to contain as much as three times the amount of carcinogens as cigarettes. Some studies suggest that there is a withdrawal syndrome when chronic marijuana use is abruptly discontinued.

The symptoms of withdrawal syndrome includes restlessness, agitation, and insomnia.⁸ The use of marijuana by adolescents has also raised concerns, as some regard marijuana use as a gateway to more serious drugs, such as heroin or cocaine.⁹


Implications for health care providers


There is widespread agreement among health care providers as to the need for further studies and medical education regarding medicinal marijuana. Many providers feel unprepared to prescribe marijuana and want formalized training regarding its medical uses. Kondrad reported that most surveyed physicians are receiving information about medicinal marijuana from the media or from other clinicians.¹⁰ 


Before a patient can receive marijuana for medicinal use, he or she must apply for a state-issued identification card.¹¹ The patient needs to be evaluated for the need for medical marijuana by a health-care provider. The application is reviewed by a public-health board that assesses the patient’s eligibility for the treatment.⁷ Once a patient is approved to receive the medication, he or she receives the marijuana from a state-approved dispensary and is eligible to receive the maximum amount permitted per month.¹²


In New Jersey, for example, clinicians and patients must be registered with the state health department’s Medical Marijuana Program (MMP) for the patient to obtain the treatment. Patients can only apply to register after a clinician registered with the program has completed a formal statement advocating the MMP for the patient.

The patient must have a diagnosis of one of the debilitating conditions that the MMP has approved for treatment with medical marijuana. Once approved, the clinician can prescribe up to 2 oz. of marijuana per month, to be dispensed in one-eighth or one-quarter-ounce packages.¹³


Many clinicians are concerned about the lack of consistency in composition of marijuana and the side effects. There is a widely held belief that medicinal marijuana is being predominantly used by those who are not ill but want legal protection for recreational use of the drug. Clinicians and patients need to be aware that growing, selling, buying, or producing marijuana in any way is a federal offense.


The ACP strongly encourages more research and funding for rigorous scientific evaluation of the potential therapeutic benefits of medical marijuana. In addition, the ACP urges evidence-based review of marijuana as a Schedule I drug to determine if it should be reclassified.

The ACP strongly promotes protection from criminal or civil penalties for patients who are legally prescribed medical marijuana under state law; the association also supports exemption from criminal prosecution, civil liability, or professional sanctioning of clinicians who prescribe the drug in accordance with state laws.² 


Conclusion


Although growing, possessing, and smoking marijuana remain illegal at the federal level, individual states have been legalizing it for medical use since 1986. The drug has been shown to have therapeutic effects in patients, but further research is needed regarding the safety and efficacy of marijuana as a medical treatment for various conditions. n 


Teri Capriotti, DO, MSN, CRNP, is a clinical associate professor and Brian Hartmann is a third-year honors student, at Villanova University College of Nursing in Villanova, Pa.


This article originally appeared on Neurology Advisor