Cannabis (marijuana) contains more than 60 pharmacologically active cannabinoids; delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are the best known. THC is the main psychoactive constituent of cannabis. CBD, unlike THC, does not produce intoxication or euphoria.

Nonopioid drugs can be used in the treatment of many nociceptive and neuropathic pain conditions. Use of opioids for pain will be reviewed in a future issue.

A reader asked why our Cannabis and Cannabinoids article (Med Lett Drugs Ther 2016; 58:97) did not include our usual Dosage/Cost table. We have now posted one in the article as it appears online. You can access it here: www.medicalletter. org/TML-article-1500a.

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In the US, 25 states and the District of Columbia now permit some medical use of botanical marijuana (Cannabis sativa). It has been used for centuries to treat various ailments, but non-standardization of dosage makes available data difficult to interpret. Cannabis contains >60 pharmacologically active cannabinoids.

Fourteen states in the US - Alaska, California, Colorado, Hawaii, Maine, Michigan, Montana, Nevada, New Jersey, New Mexico, Oregon, Rhode Island, Vermont and Washington - now permit, or soon will permit, some medical use of marijuana (Cannabis sativa). In some states, licensed facilities dispense botanical cannabis by prescription. In others, limited self-cultivation is permitted for medical use.

Many drugs can cause psychiatric symptoms, but a causal connection is often difficult to establish. Psychiatric symptoms that emerge during drug treatment could also be due to the underlying illness, previously unrecognized psychopathology, or psychosocial factors. The withdrawal of some drugs can cause symptoms such as anxiety, psychosis, delirium, agitation or depression.

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Nabilone, an oral synthetic cannabinoid similar to delta-9-tetrahydrocannabinol (THC), the active ingredient in marijuana, has recently been reintroduced to the US market (Cesamet - Valeant) after a 17-year absence. The previous manufacturer discontinued marketing of the drug for commercial reasons. Nabilone is classified as a Schedule II controlled substance.

Many drugs can cause psychiatric symptoms, but a causal connection is often difficult to establish. Psychiatric symptoms that emerge during drug treatment may also be due to the underlying illness, previously unrecognized psychopathology, or psychosocial factors. The withdrawal of some drugs can cause symptoms such as anxiety, psychosis, delirium, agitation or depression.

Older patients are especially susceptible to drug-induced cognitive impairment. They are more likely to be taking multiple drugs, to have higher blood levels of those drugs because of renal or hepatic dysfunction, and to have pre-existing cognitive problems that make it difficult to detect the role of drugs causing new symptoms or making old ones worse.

Granisetron, a serotonin (5-HT) antagonist similar to ondansetron, was recently approved by the US Food and Drug Administration for prevention of nausea and vomiting due to cancer chemotherapy. Although available in an oral formulation in other countries, granisetron is available here only for intravenous (IV) use.

Several currently available antiemetic drugs can prevent vomiting caused by cancer chemotherapy. Anticancer drugs that cause vomiting are listed in the table below.

Ondansetron (on dan' se tron; Zofran - Glaxo), a serotonin (5-hydroxytryptamine) antagonist, was recently marketed in the USA for intravenous use to prevent nausea and vomiting due to cancer chemotherapy. An oral formulation is available in many other countries.

Nabilone (Cesamet - Lilly), a synthetic cannabinoid chemically related to tetrahydrocannabinol (THC), the main active ingredient in marijuana, was recently marketed in the USA for oral treatment of nausea and vomiting associated with cancer chemotherapy. Oral THC itself, known generically as dronabinol (Marinol), is also commercially available as an antiemetic for cancer patients (Medical Letter, 27:97, 1985). Other drugs used for this purpose include metoclopramide (Reglan - Medical Letter, 24:67, 1982), prochlorperazine (Compazine; and others), haloperidol (Haldol; and others), and corticosteroids. Benzodiazepines, such as lorazepam (Ativan; and others), are used to treat anticipatory nausea and vomiting that occurs before chemotherapy begins.