Cannabinoids

Medical Uses

Medical uses for marijuana have been ubiquitous for centuries in Asia, Southeast Asia, and India. Hemp was used to expel flatulence, excite the appetite, and induce eloquence. Both stimulant and sedative effects have been described as being dose-related, with higher doses producing more sedative-like effects. The early explorations of the medical uses of cannabis focused on its ability to cause profound “narcoticism,” demonstrating effectiveness in the treatment of a case of infantile convulsions. It also resulted in a “singular form of delirium which the incautious use of the hemp preparations often occasions, especially among young men first commencing the practice” (O’Shaughnessy WB. On the preparations of the Indian hemp, or gunjah. Transactions of the Medical and Physical Society of Bengal, 1838–1840, pp. 421–461). Describing a state of intoxication, the user is said to have “a strange balancing gait, perpetual giggling, expressions of cunning and merriment, increased libido and a voracious appetite” (O’Shaughnessy WB. On the preparations of the Indian hemp, or gunjah. Transactions of the Medical and Physical Society of Bengal, 1838–1840, pp. 421–461).

Possible indications for the medical use of cannabis preparations are numerous (Table 8.5). Cannabinoids have two currently accepted medical uses in the United States. Dronabinol (Marinol; the pure isomer of Δ9-THC) and nabilone (Cesamet; a synthetic analog of THC) are approved for use in refractory nausea and vomiting associated with cancer chemotherapy and appetite loss in HIV/AIDS patients with anorexia (see Table 8.4). Potential medical effects that have been relatively less well confirmed include the amelioration of spasticity caused by spinal cord injury and multiple sclerosis. Cannabinoids are effective analgesics and have shown some effectiveness in chronic pain conditions. They have also been shown to be effective in asthma and in lowering intraocular pressure in patients with glaucoma. Cannabinoids have been hypothesized for use in the treatment of movement disorders, including dystonias, dyskinesias, and tardive dyskinesia. Other proposed actions of cannabinoids that are largely unconfirmed but are being studied range from the treatment of allergies and inflammation to epilepsy and psychiatric disorders.

FIGURE 8.3 Cumulative percentage of 218 subjects aged 13–19 who had used the drugs shown either once (solid line) or at least monthly (dashed line) by various ages. Subjects for this study were patients admitted to a substance abuse treatment program between 1991 and 1994. All patients had: (1) significant antisocial problems, diagnosed substance problems, and diagnosed conduct disorder, (2) been judged by clinical staff not to be currently psychotic, mentally retarded, homicidal, suicidal, or a current arson risk, (3) no physical illness which would prevent participation in active, group-oriented treatment, (4) written, informed consent from a parent or guardian, (5) assent from the youth. These data suggest that cannabis, like alcohol and tobacco, is used at significantly earlier ages than other drugs of abuse. Such data can be considered to support a Gateway-like hypothesis or simply that availability is a major factor. Alcohol, tobacco, and cannabis are the most used drugs overall in the population of the United States . [Data from Crowley TJ, Macdonald MJ, Whitmore EA, Mikulich SK. Cannabis dependence, withdrawal, and reinforcing effects among adolescents with conduct symptoms and substance use disorders. Drug and Alcohol Dependence, 1998, (50), 27–37. Modified from Koob GF, Le Moal M. Neurobiology of Addiction. London: Academic Press, 2006.]

FIGURE 8.4 Percentage of persons aged 12–17 and 18–25 who had ever used marijuana through the year 2011. These data show that the initial rise in marijuana use in the United States occurred in the 1960s, followed by a peak in the 1980s, a decrease in the 1990s, and a resurgence of use that has stabilized from 2000 on. The increases in the use of marijuana over the years correspond to and parallel the inverse of perceived risk over the same period. In other words, during the 1990s when the use of marijuana was low, the perceived risk was high. Conversely, in the years when use was high, the perceived risk was low. [Data from Substance Abuse and Mental Health Services Administration, National Survey on Drug Use and Health.]

Table 8.5

Potential Medical Uses of Cannabinoids

Well Confirmed Clinical Effects

  • refractory nausea / vomiting
  • anorexia appetite loss
  • HIV/AIDS/cancer cachexia

LESS WELL CONFIRMED CLINICAL EFFECTS

  • spasticity due to spinal cord injury
  • multiple sclerosis
  • neurogenic pain, neuropathy, allodynia
  • movement disorders (Tourette’s syndrome; dystonia; dyskinesia)
  • bronchodilation effects
  • glaucoma

LARGELY UNEXPLORED BUT POSSIBLE CLINICAL EFFECTS

  • epilepsy
  • hiccups
  • bipolar disorder
  • Alzheimer’s disease
  • alcohol dependence

BASIC RESEARCH

  • amyloid formation
  • opiate withdrawal
  • ischemia
  • hypertension
  • neoplasms
  • diarrhea
  • bronchospasms
  • sleep apnea
  • colonic inflammation
  • irritable bowel syndrome
  • cough
  • Huntington’s disease
  • optic nerve damage

See Table 8.4

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