There are marked differences in the knowledge on the medical uses of cannabis and cannabinoids in different diseases. For nausea and vomiting associated with cancer chemotherapy, anorexia and cachexia in HIV/AIDS, spasticity in multiple sclerosis and spinal cord injury there is strong evidence for medical benefits. For many other indications, such as epilepsy, movement disorders and depression there is much less available data.
Clinical studies with single cannabinoids or, less often with whole plant preparations (smoked marijuana, encapsulated cannabis extract) have often been inspired by positive anecdotal experiences of patients employing crude cannabis products. The anti-emetic, the appetite enhancing, relaxing effects, analgesia, and therapeutic use in Tourette's syndrome were all discovered in this manner.
Incidental observations have also revealed therapeutically useful effects in a study with patients with Alzheimer's disease wherein the primary issue was an examination of the appetite- stimulating effects of THC. Not only appetite and body weight increased, but disturbed behaviour among the patients also decreased. The discovery of decreased intraocular pressure with THC administration in the beginning of the 1970s was also serendipitous. For this reason, more surveys have been conducted in the past decade questioning individuals that use cannabis therapeutically.
(Donald P. Tashkin):
The smoke contents of marijuana are at least qualitatively similar to those of tobacco, with the major exception that marijuana smoke contains delta-9-tetrahydrocannabinol (delta-9-THC) and approximately 60 additional cannabinoid compounds not found in tobacco and that tobacco contains nicotine that is absent from marijuana. Many of the ingredients that are common to marijuana and tobacco smoke are known to be toxic to respiratory tissue. These toxic components include hydrocyanic acid, oxides of nitrogen, acrolein, reactive aldehydes and several known carcinogens. It is therefore reasonable to expect that repeated inhalation of the noxious components in cannabis smoke may have long-term adverse effects on the lung similar to those that have been observed in regular tobacco smokers.
Tashkin DP. Respiratory risks from marijuana smoking. Grotenhermen F, Russo E, eds. Cannabis and cannabinoids. Pharmacology, toxicology, and therapeutic potential. Binghamton NY: Haworth Press, 2001, in press.
The major strategies to reduce the risks of smoking are:
- The use of cannabis strains with high THC content. (...) - The use of pure cannabis. Sometimes cannabis is smoked together with tobacco or other dried herbs. This procedure should be avoided to minimize the inhalation of smoke from burnt plant material.
- The use of pipes. Pipes are superior to cigarettes in some situations in that they easily allow the patient to smoke small amounts of pure high-grade cannabis. The percentage of tars in the smoke is reduced by condensation on the pipe walls. Pipes should be cleaned frequently. Water pipes are inferior to cigarettes and should be avoided. (...)
- The use of cannabis that is free of natural contaminants and adulterants. Only disease-free cannabis should be harvested and air-dried. (...)
- The use of inhalation devices that reduce output of tars. (...) Gieringer tested vaporizers that heat marijuana to 180-190°C vaporizing THC below the burning point of cellulose and other plant material. The production of polycyclic hydrocarbons was reduced. The best vaporizer delivered 10 parts of tar to one part of cannabinoids, cannabis cigarettes yielded a ratio of 13:1 (average), and water pipes an average of 27:1 (...). Thus, the best vaporizers achieved a performance ratio about 25% higher than the unfiltered cannabis cigarette, while water pipes were less favorable than cigarettes. The use of a filter in a cannabis cigarette was not advantageous since it not only filtered the tars, but also the cannabinoids. Indeed, the performance ratio was decreased by about 30% compared to the unfiltered cigarette.
In a new study Gieringer was able to demonstrate that combustion products were substantially reduced by using another vaporizer. The used device produced THC at a temperature of 185°C while completely eliminating benzene, toluene and naphthalene. Significant amounts of benzene began to appear at temperatures of 200°C, while combustion occurred around 230°C or above. Traces of THC were in evidence as low as 140°C. Carbon monoxide and tars were both qualitatively reduced by the vaporizer, but were not quantificated in this study. However, a significant reduction of polycyclic aromatic hydrocarbons was assumed since vaporized cannabis emitted a thin gray vapor and the plant material was left with a green to greenish-brown "toasted" appearance, whereas the combusted sample produced thick smoke and turned to ash. (...)
- Combination of oral use and inhalation. In several indications, a combined regime of a basic oral medication with cannabis or THC and a demand inhaled medication may be useful to reduce risks from smoking and from possible overdosage with oral administration.
Grotenhermen F. Harm reduction associated with inhalation and oral administration of cannabis and THC. Journal of Cannabis Therapeutics 2001, in press.
Cannabis exerts manifold effects on the vegetative nervous system, among them increased heart rate, dry mouth, slowdown of intestinal movements, changes of blood pressure (decrease and increase). These effects are usually mild and well tolerated. Their intensity varies from person to person. In some subjects an unusual intensity of these side effects and unusual kinds of vegetative side effects have been observed, Among them strong increase of heart rate, strong increase of blood pressure, shivering and chills, bellyache, headache, nausea and vomiting.
The following experiences were told to me by recreational users: A young man who had used cannabis for many years without relevant side effects experienced strong headache after the use of LSD which made him to attend a hospital. A high blood pressure (systolic pressure of 190 mmHg) was measured. Later every use of cannabis also resulted in headache and significant increase of blood pressure. Another user reported signficant and frightening increase of heart rate (140 beats per minute) lasting for more than one hour occuring sometimes after use of the drug. Two cannabis users reported of bellyache within a few minutes after smoking of whom one experienced flatulences. Another user experienced chills and shivering every time he used the drug. In the internet (http://rxmarijuana.com) I found the report of a man who complained of several symptoms, significant increase of heart rate, anxiety, painful belching, and chills.
Adverse experiences information summarized in the tables below was derived from well-controlled clinical trials conducted in the US and US territories involving 474 patients exposed to Marinol (dronabinol). Studies of AIDS related weight loss included 157 patients receiving dronabinol at a dose of 2.5 mg twice daily and 67 receiving placebo. Studies of nausea and vomiting related to cancer chemotherapy included 317 patients receiving dronabinol and 68 receiving placebo. A cannabinoid dose-related "high" (easy laughing, elation and heightened awareness) has been reported by patients receiving Marinol in both the antiemetic (24%) and the lower dose appetite stimulant clinical trials (8%).
The most frequently reported adverse experiences in patients with AIDS during placebo-controlled trials involved the CNS [central nervous system] and were reported by 33% of patients receiving Marinol. About 25% of patients reported a minor CNS adverse event during the first 2 weeks and about 4% reported such an event each week for the next 6 weeks thereafter.
PROBABLY CAUSALY RELATED: Incidence greater than 1%.
Rates derived from clinical trials in AIDS-related anorexia [appetite loss] (N=157) and chemotherapy-related nausea (N=317). Rates were generally higher in the anti-emetic use (given in parenthesis). [Explanation of technical terms in square brackets].
Body as a whole: Asthenia [loss or lack of strength or energy].
Cardiovascular [related to heart and circulation]: Palpitation [uneasy awareness of the heart beat], tachycardia [fast heart rate], vasodilation/facial flash.
Digestive [related to digestion]: Abdominal pain, nausea, vomiting.
Nervous system: (Amnesia), anxiety/nervousness, (ataxia [disturbance of muscle coordination]), confusion, depersonalization, dizziness, euphoria, (hallucination), paranoid reaction, somnolence, thinking abnormal.
PROBABLY CAUSALY RELATED: Incidence less than 1%.
Event rates derived from clinical trials in AIDS-related anorexia (N=157) and chemotherapy-related nausea (N=317).
Cardiovascular: Conjunctivitis [reddening of the eye], hypotension.
Digestive: Diarrhea, fecal incontinence.
Musculosceletal: Myalgia [pain in the muscles].
Nervous system: Depression, nightmares, speech difficulties, tinnitus [ear noise].
Skin and Appendages [hair and nails]: Flushing.
Special senses: Vision difficulties.
CAUSALY RELATIONSHIP UNKNOWN: Incidence less than 1%.
The clinical significance of the association of these events with Marinol treatment is unknown, but they are reported as alerting information for the clinician.
Body as a whole: Chills, headache, malaise.
Digestive: Anorexia, hepatic enzyme elevation.
Respiratory: Cough, rhinitis, sinusitis.
Skin and Appendages: Sweating.
Source: Information on Marinol (dronabinol, THC), Unimed Pharmaceuticals, Inc., January 2001, www.marinol.com (physicians information).