The Science of Marijuana by Leslie Iversen

Author:Leslie Iversen
Language: eng
Format: epub, pdf
Publisher: Oxford University Press
Published: 2018-03-11T16:00:00+00:00

Nausea and Vomiting Associated with Cancer Chemotherapy

One of the most distressing symptoms in medicine is the prolonged nausea and vomiting which regularly accompanies treatment with many anti-cancer agents. This can be so severe that patients come to dread their treatment; some find the side-effects of the drugs worse than the disease they are designed to treat; others find the symptoms so intolerable that they decline further therapy despite the presence of malignant disease.

— BRITISH MEDICAL ASSOCIATION (1997, p. 21)

Ironically, this condition for which there was the earliest scientific evidence for beneficial effects of cannabis-based medicines is now no longer viewed as an area of pressing medical need because new and even more powerful anti-sickness drugs have become available. Currently, 48 prescription medicines are available for the indication of vomiting (Drugs.com, 2016). When the cannabinoids dronabinol and nabilone were first being tested in the 1970s and early 1980s, however, matters were different.

Among the most effective anti-cancer drugs are the platinum-containing compound cisplatin, the plant product taxol, and numerous modern versions; unfortunately, they are also very powerful in causing nausea and vomiting. Cancer patients receiving these drugs almost invariably experience nausea and vomiting, with an average of six bouts of vomiting during the first 24 hours, unless they are protected by anti-emetic medicines. The initial reaction is followed by a delayed phase of nausea and vomiting during the next few days. The results of properly controlled clinical trials conducted in the 1970s and 1980s indicated that the two cannabinoid drugs dronabinol and nabilone appeared to offer a potentially important advance over the relatively ineffective anti-sickness medicines available in the early 1980s (Abrahamov et al, 1995; for review, see Tramer et al., 2001). The most widely used drugs then were chlorpromazine, prochlorperazine, haloperidol, metoclopramide, and domperidone—all of which act as antagonists of the chemical messenger dopamine. Various clinical trials in which dronabinol was compared with placebo or with another anti-sickness agent, prochlorperazine, reported the efficacy of dronabinol (for review, see Mücke et al., 2016).

The manufacturer of nabilone, Eli Lilly, conducted approximately 20 separate clinical trials involving more than 500 patients, many with a double-blind crossover design to allow the direct comparison of nabilone with prochlorperazine or other anti-emetic medicines in the same patients. Nabilone proved to be as effective as prochlorperazine, or more so, and it successfully treated the symptoms of nausea and vomiting in 50–70% of patients. Central nervous system side effects of drowsiness, light-headedness, and dizziness were seen in more than half of the patients, but these were not considered serious, and only a small proportion of patients (approximately 15%) experienced a “high” (Lemberger, 1985). The FDA granted formal approval of nabilone as an anti-emetic without causing intoxication, but the US Drug Enforcement Agency concluded that nabilone was still too much like cannabis, and it gave nabilone a restrictive Schedule II classification—that is, it was considered to be a potentially dangerous drug of addiction, although it did have some medical usefulness. The Schedule II classification was disappointing to Eli Lilly because

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