Febr 19, 2007
By: Bonnie Darves
Docguide.com

SALT LAKE CITY, UT — Clinicians treating patients who have chronic pain are more likely to achieve optimal results if they first identify the cause of the pain, and then reiterate doses frequently and reassess continually the regimen's effectiveness.

And for patients with severe, persistent pain, physicians should use long-acting opioids around the clock, rather than as needed, in concert with short-acting drugs for breakthrough pain — in doses retitrated often enough to ensure that patients do not end up in pain crisis.

This comprehensive strategy is key to managing chronic pain but it is one that physicians who are not pain specialists are sometimes reluctant to employ, according to palliative medicine specialist Bruce Chamberlain, MD, chief medical officer, VistaCare, Orem, Utah.

"That's the fundamental rule of pain management, along with 'start low and go slow'," Dr. Chamberlain said during his presentation here on February 16th at the American Academy of Hospice and Palliative Medicine annual assembly (AAHPM).

"That's why I don't like standing orders for medications, because as a physician I need to know what has changed [in the patient's condition]," he said, to ensure the patient is receiving enough medication, often enough.

Some physicians have "mental thresholds" about dosing, he said, such as an unwillingness to give more than 100 mg of certain opioids, that may unwittingly thwart their intentions to provide adequate pain control. "There is no ceiling dose," he said, provided increases have occurred gradually.

While acknowledging the difficulties inherent in treating patients with chronic pain, Dr. Chamberlain said physicians fail to achieve good pain control for 3 common reasons — they use the wrong medications or routes of administration; starting with the wrong dose of an effective medication; or failing to assess the patient frequently enough to ensure that dosage adjustments are made as needed. Using noninvasive routes initially and adopting the "start low and go slow" approach to dosing of opioids, in particular, regardless of route, can avoid many problems down the road.

"It's important to use the least invasive modalities first, because 90% of pain can be treated noninvasively initially," Dr. Chamberlain said. He cited sublingual, oral, and transdermal administration as the least invasive routes, and oral as the most preferred by patients. Of the 3, however, transdermal administration of drugs such as fentanyl can be problematic because their absorption can be unpredictable in certain patients — particularly those with low or high body fat, and patients with massive ascites. That can lead to a "patches everywhere" situation that still leaves some patients with uncontrolled pain, while even the lowest strength (25 mcg) could be intolerable to opiate-naive patients in whom systemic release occurs relatively quickly.

Dr. Chamberlain noted that more than half of patients with terminal cancer will require multiple routes of medication administration — including invasive routes — during the final month of their lives. But he cautioned that many patients may perceive such technically noninvasive routes as rectal or vaginal as invasive, and that invasive routes such as intramuscular injection are best avoided. "Injections are not ideal, and for the patient in pain, that can seem like a punitive approach," he said.

One common mistake prescribers make is to "use up" a good medication such as an opioid by starting with an initial dose that is too high. Potentially severe adverse effects such as nausea and oversedation, he said, may end up causing patients to decline a subsequent trial and lower dose of the medication.

In discussing other potential pain management problem areas, Dr. Chamberlain urged attendees to avoid using opiates such as merperideine and propoxyphene. Merperideine is weak in oral form compared with morphine and is associated with serious adverse effects such as seizures, while propoxyphene has potentially serious neurotoxic effects yet relatively poor (equivalent to aspirin or acetaminophen) analgesic effect. Mixed agonist-antagonist opiates such as butorphanol and pentazocine are also best avoided, Dr. Chamberlain explained, because of their limited maximum dosing and potential for causing withdrawal symptoms when combined with other opiates.

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