MARIHUANA: AN OLD MEDICINE OF THE FUTURE
LESTER GRINSPOON, M.D.
JAMES B. BAKALAR
|In November 1996 the people of California
approved Proposition 215, an initiative that could, in
effect, make marihuana legally available as a medicine in
the United States for the first time in many years. Under
the new law, patients or their primary caregivers who
possess or cultivate marihuana for medical treatment
recommended by a physician are exempted from criminal
prosecution. The treatment may be for "cancer,
anorexia, AIDS, chronic pain, spasticity, glaucoma,
arthritis, migraine, or any other illness for which
marihuana provides relief." Physicians may not be
penalized in any way for making the recommendation, which
may be either written or oral.1 The
passage of this law is only the beginning of a trend that
presents new challenges for physicians, who will be asked
to assume responsibilities for which many have not
prepared themselves. As more and more patients approach
them with questions about marihuana, they will have to
provide answers and make recommendations. That means they
must not only listen more carefully to their patients but
educate themselves and one another. They will have to
learn which symptoms and disorders may be treated better
with marihuana than with conventional medications, and
they may need to explain how to use marihuana.
Cannabis is a strikingly safe, versatile, and potentially inexpensive medicine. When we reviewed its medical uses in 1993 after examining many patients and case histories, we were able to list the following: nausea and vomiting in cancer chemotherapy, the weight loss syndrome of AIDS, glaucoma, epilepsy, muscle spasms and chronic pain in multiple sclerosis, quadriplegia and other spastic disorders, migraine, severe pruritus, depression, and other mood disorders.2 Since then we have identified more than a dozen others, including asthma, insomnia, dystonia, scleroderma, Crohns disease, diabetic gastroparesis, and terminal illness. The list is not exhaustive.3
For example, cannabis has also been found useful in the treatment of osteoarthritis. Aspirin is believed to cause more than 1,000 deaths annually in the United States. More than 7,600 annual deaths and 70,000 hospitalizations caused by non-steroidal antiinflammatory drugs (NSAIDs) are reported. Gastrointestinal complications of NSAIDs are the most commonly reported serious adverse drug reaction.4 Long-term acetaminophen use is thought to be one of the most common causes of end-stage renal disease.5 Cannabis smoked several times a day is often as effective as NSAIDs or acetaminophen in osteoarthritis, and there have been no reports of death from cannabis.
It is often objected that the evidence of marihuanas medical usefulness, although powerful, is merely anecdotal. It is true that there are no studies meeting the standards of the Food and Drug Administration, chiefly because legal, bureaucratic, and financial obstacles are constantly put in the way. The situation is ironical, since so much research has been done on marihuana, often in unsuccessful efforts to show health hazards and addictive potential, that we know more about it than about most prescription drugs. In any case, controlled studies can be misleading if the wrong patients are studied or the wrong doses are used, and idiosyncratic therapeutic responses can be obscured in group experiments.
Anecdotal evidence is the source of much of our knowledge of drugs. As Louis Lasagna has pointed out, controlled experiments were not needed to recognize the therapeutic potential of chloral hydrate, barbiturates, aspirin, insulin, or penicillin.6 Anecdotal evidence also revealed the usefulness of propranolol and chlorothiazide for hypertension, diazepam for status epilepticus, and imipramine for enuresis. All these drugs had originally been approved for other purposes.
Some physicians may regard it as irresponsible to support, let alone advocate the medical use of cannabis on the basis of anecdotal evidence, which seems to count successes and ignore failures. That would be a serious problem only if cannabis were a dangerous drug. The years of effort devoted to showing that marihuana is exceedingly dangerous have proved the opposite. It is safer, with fewer serious side effects, than most prescription medicines, and far less addictive or subject to abuse than many drugs now used as muscle relaxants, hypnotics, and analgesics.
Thus it can be argued that even if only a few patients could get relief from cannabis, it should be made available because the risks would be so small. For example, many patients with multiple sclerosis find that cannabis reduces their muscle spasms and pain. A physician may not be sure that such a patient will get better relief from marihuana than from the baclofen, dantrolene, and high doses of diazepam that the patient has been taking, but it is certain that a serious toxic reaction to marihuana is extremely unlikely, and risk-benefit considerations therefore make it worth trying. However, some preparation and instruction may be required, both to realize therapeutic goals and to avoid unwanted reactions. The psychoactive effects, for example, must be explained to marihuana-naive patients, who may otherwise suffer some anxiety at first.
The chief legitimate concern is the effect of smoking on the lungs. Many physicians find it difficult to endorse a smoked medicine. Although cannabis smoke carries even more tars and other particulate matter than tobacco smoke, the amount needed by most patients is extremely limited. Furthermore, when marihuana is an openly recognized medicine, solutions for this problem may be found, perhaps by the development of a technique for inhaling cannabinoid vapors. Even today, the greatest danger of using marihuana medically is not impurities in the smoke but illegality, which imposes much unnecessary anxiety and expense on suffering people.
A synthetic version of delta-9-tetrahydrocannabinol, the main active substance in cannabis, has been available in oral form for limited purposes as a Schedule II drug since 1985. This medicine, dronabinol (Marinol), is generally regarded by both patients and physicians as less effective than smoked marihuana. A patient who is severely nauseated and constantly vomiting, for example, may find it almost impossible to keep a pill or capsule down. Oral THC is erratically and slowly absorbed into the bloodstream; the dose and duration of action of smoked marihuana are easier to titrate. Furthermore, oral THC occasionally makes many patients anxious and uncomfortable, possibly because cannabidiol, one of the many substances in marihuana, has an anxiolytic effect.7
Besides their direct responsibility to individual patients with respect to medical marihuana, physicians have another obligation that is social and ultimately political. Jerome P. Kassirer has identified it in his recent New England Journal of Medicine editorial entitled "Federal Foolishness and marihuana." He describes the governments policies on medical marihuana as "hypocritical" and predicts that physicians who "have the courage to challenge the continued proscription of marihuana for the sick" will eventually force the government to reach some sort of accommodation.8 That important task will inevitably fall to the younger generation of doctors, including present and future medical students.