Cannabis and Chronic Pain
Many older patients suffer from persistent and disabling pain, which can have numerous and sometimes multiple causes. These include cancer; arthritis and other rheumatic and degenerative hip, joint and connective tissue disorders; diabetes; AIDS; sickle cell anemia; multiple sclerosis; defects or injuries to the back, neck and spinal cord; and severe burns. Pain is not a primary condition or injury, but is rather a severe, frequently intolerable symptom that varies in frequency, duration, and severity according to the individual. The underlying condition determines the appropriate curative approach, but does not determine the proper symptom management. It is the character, severity, location and duration of the pain that determines the range of appropriate therapies.
For patients in pain, the goal is to function as fully as possible by reducing their pain as much as possible, while minimizing the often debilitating side effects of the pain therapies. Failure to adequately treat severe and/or chronic pain can have tragic consequences. Not infrequently, people in unrelieved pain want to die. Despair can also cause patients to discontinue potentially life-saving procedures (e.g., chemotherapy or surgery), which themselves cause severe suffering. In such dire cases, anything that helps to alleviate the pain will prolong these patients’ lives.
Cannabis can serve at least two important roles in safe, effective pain management. It can provide relief from the pain itself (either alone or in combination with other analgesics), and it can control the nausea associated with taking opiod drugs, as well as the nausea, vomiting and dizziness that often accompany severe, prolonged pain.
Opioid therapy is often an effective treatment for severe pain, but all opiates have the potential to induce nausea. The intensity and duration of this nausea can cause enormous discomfort and additional suffering and lead to malnourishment, anorexia, wasting, and a severe decline in a patient’s health. Some patients find the nausea so intolerable that they are inclined to discontinue the primary pain treatment, rather than endure the nausea.
Inhaled cannabis provides almost immediate relief for this, with significantly fewer adverse effects than orally ingested Marinol. Inhalation allows the active compounds in cannabis to be absorbed into the blood stream with greater speed and efficiency. It is for this reason that inhalation is an increasingly common, and often preferable, route of administration for many medications. Cannabis may also be more effective than Marinol because it contains many more cannabinoids than just the THC that is Marinol’s active ingredient. The additional cannabinoids may well have additional and complementary antiemetic qualities. They have been conclusively shown to have better pain-control properties when taken in combination than THC alone.
Research on cannabis and pain management
Cannabis has historically been used as an analgesic,[35-36] and patients often report significant pain relief from marijuana.[37-42] Some of the most encouraging clinical data on the effects of cannabinoids on chronic pain are from studies of intractable cancer pain and hard-to-treat neuropathic pain.[43-44]
After reviewing a series of trials in 1997, the U.S. Society for Neuroscience concluded that “substances similar to or derived from marijuana could benefit the more than 97 million Americans who experience some form of pain each year.”
A 1999 study commissioned by the White House and conducted by the Institute of Medicine recognizes the role that cannabis can play in treating chronic pain. “After nausea and vomiting, chronic pain was the condition cited most often to the IOM study team as a medicinal use for marijuana.”
The study found that “basic biology indicates a role for cannabinoids in pain and control of movement, which is consistent with a possible therapeutic role in these areas. The evidence is relatively strong for the treatment of pain and intriguingly, although less well established, for movement disorder.” According to the report, a number of brain areas that have an established role in sensing and processing pain respond to the analgesic effect of cannabis, such that cannabinoids have been used successfully to treat cancer pain, which is often resistant to treatment with opiates.
The Report further notes that cannabinoids serve as an anti-inflammatory agent, and so have therapeutic potential in preventing and reducing pain caused by the swelling of body tissues (such as arthritis).
In addition to its analgesic properties, the Report indicates that cannabis, like its synthetic cousin Marinol, can help treat the nausea often induced by opiate therapy, especially when other antiemetics prove ineffective. In short, the IOM Report recognizes the potential benefits of cannabis for certain patients, including:
· Chemotherapy patients, especially those being treated for mucositis, nausea, and anorexia.
· Postoperative pain patients (using cannabinoids as an opioid adjunct to reduce the nausea and vomiting).
· Patients with spinal cord injury, peripheral neuropathic pain, or central post-stroke pain.
· Patients with chronic pain and insomnia.
· AIDS patients with cachexia, AIDS neuropathy, or any significant pain problem.
Britain’s House of Lords reached similar conclusions and called for legalized cannabis by prescription.
Several studies have found that cannabinoids have analgesic effects in animal models, sometimes equivalent to codeine.[48-52] Cannabinoids also seem to synergize with opiods, which often lose their effectiveness as patients build up tolerance. One study in rats found morphine was 15 times more active with the addition of a small dose of THC. Codeine was enhanced on the order of 900 fold.
In 1990, researchers conducted a double-blind study comparing the antispasmodic and analgesic effects of THC, oral Codeine, and a placebo on a single patient suffering from a spinal cord injury. Their findings confirmed the analgesic effects of THC being “equivalent to codeine.” A 1997 study made similar findings related to morphine.
A 1999 article reviewing the body of scientific animal research concerning the analgesic effects of marijuana concludes that “[t]here is now unequivocal evidence that cannabinoids are antinociceptive [capable of blocking the appreciation or transmission of pain] in animal models of acute pain.”
In 2001, British researchers reported that cannabis extract sprayed under the tongue was effective in reducing pain in 18 of 23 patients who were suffering from intractable neuropathic pain.
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