Medical marijuana: clearing away the smoke

Abstract

Recent advances in understanding of the mode of action of tetrahydrocannabinol and related cannabinoid in-gredients of marijuana, plus the accumulating anecdotal reports on potential medical benefits have spurred increasing re-search into possible medicinal uses of cannabis. Recent clinical trials with smoked and vaporized marijuana, as well as other botanical extracts indicate the likelihood that the cannabinoids can be useful in the management of neuropathic pain, spasticity due to multiple sclerosis, and possibly other indications. As with all medications, benefits and risks need to be weighed in recommending cannabis to patients. We present an algorithm that may be useful to physicians in determining whether cannabis might be recommended as a treatment in jurisdictions where such use is permitted.

Keywords: Cannabis; chronic pain; pain..

Fig. (1)

A decision tree approach for physicians who may be considering recommending medicinal cannabis to a patient. This decision tree suggests some key points that a physician may need to consider in making his/her determination. In this case, a patient is assumed to present with persistent neuropathic pain. Initially, a determination needs to be made that the patient’s signs and symptoms are indeed consistent with this diagnosis. Assuming a patient does not respond favorably to more standard treatments (e.g., antidepressants, anticonvulsants, etc), or cannot tolerate those, and the patient is willing to consider medicinal cannabis, the physician needs to determine risk versus benefit. Among these considerations is whether there is a history of substance abuse or serious psychiatric disorder that might be exacerbated by medicinal cannabis. Even if such risks exists, this does not necessarily preclude the use of medicinal cannabis; rather coordination with appropriate substance abuse and psychiatric resources is necessary, and based on such consultation a risk benefit ratio can be determined. In patients in whom the ratio appears favorable, the physician needs to discuss alternative modes of cannabis administration which may include oral, smoked, or vaporized systems. Once risks and benefits are evaluated and discussed with the patient, cannabis treatment may commence as with other psychotropic medications, with attention being paid to side effects as well as efficacy. In addition, there needs to be attentiveness to potential for misuse and diversion, which can then trigger a decision to discontinue. Key

1. Daily or almost daily pain with typical neuropathic characteristics for at least 3 months; affects life quality.

2. Standard Rx = e.g., antidepressants, anticonvulsants; opioids; nonsteroidal anti-inflammatory drugs.

3. For example, at least 30% reduction in pain intensity.

4. Consider past experience, possible past history of side effects; willingness to smoke.

5. Determine history of substance abuse. If yes, or at “high risk” aberrant for drug behavior; proceed with close observation; possibly coor-dinate with substance abuse treatment program.

6. Efficacy = at least 30% reduction in pain intensity.