COLUMBUS, Ohio--Cancer pain patients on opioid therapy who request
more medication, or more frequent dosing, are almost always
responding to an increase in pain, said Steven Passik, PhD, director,
Oncology Symptom Control and Research, Community Cancer Care, Indianapolis.
If their need for medication goes unmet, patients may exhibit
drug-seeking behavior. This, in turn, may prompt the patients
physicians into mistakenly believing that opioid therapy has turned
their patients into drug addicts, he said at a pain seminar sponsored
by the Ohio State University Medical Center.
Such an event is extremely unlikely and reflects widespread confusion
over distinctions between addiction, tolerance, and physical
dependence, Dr. Passik said. One study (the Boston Collaborative Drug
Surveillance Project) evaluated 11,882 patients who had no history of
drug abuse and found iatrogenic addiction in only 4 patients.
Understanding the Concepts of Tolerance, Physical Dependence, and Addiction
Physicians must understand the concepts of opioid tolerance and
Tolerance, defined as the need for increasing opioid doses to
Physical dependence is a pharmacologic effect characteristic of
Addiction, or substance dependence disorder, however, is
Drug-seeking behavior in response to pain is known as
pseudoaddiction, a term coined in 1989 by Drs. David Weissman and J.
David Haddox, he said. The syndrome resolves when pain medication is increased.
Studies have shown that a significant percentage of physicians fear
causing opioid addiction in their patients. Patients, too, fear
addiction. Indeed, these concerns are frequently cited as one of
several barriers to the adequate treatment of cancer pain.
The fear of addiction is based, not on reality, but on the myths that
surround the use of opioids for pain treatment, primarily that such
use will lead to drug abuse or addiction, Dr. Passik said. "This
is controversial therapy, and there are lots of misunderstandings
about it," he commented.
Drug-seeking behavior spans a spectrum of actions. A patient may
aggressively complain about the need for more drugs, make unscheduled
doctor visits, request a specific drug by name, or even acquire the
drug from other medical sources. The patient may occasionally
escalate the drug dosage without physician approval. These behaviors,
Dr. Passik said, are suggestive of pseudoaddiction.
Behaviors that are more typically associated with addiction, more
accurately called substance dependence disorder, include injecting
oral formulations, repeatedly escalating drug dosages, or forging prescriptions.
"We need to ask: What is the patient after?" Dr. Passik
said. "Pain control? Or a desire for access to drugs to get high
or to get rich? Are they self-medicating depression? Anxiety?"
A physician faced with a patient who shows drug-seeking behavior
should consider pseudoaddiction as one possible diagnosis.
Psychiatric disorder, depression, mild encephalopathy, and anxiety
disorder should also be considered, as well as substance dependence
disorder and criminal intent.
The diagnosis becomes even more complex when treating patients who
are or have been substance abusers. "This is a very hard
differential diagnosis in practice," Dr. Passik said. Although
the treatment of pain is the same regardless of the patients
substance abuse history, the structure of the treatment plan may
change, he said. Treatment may require a multidisciplinary team that
includes an expert in addiction medicine, for instance.
To better understand pseudoaddic-tion, medical science needs to learn
more about the behaviors of various populations undergoing opioid
therapy, Dr. Passik said. In a study of cancer patients without a
history of substance abuse, he found that 39% had taken unsanctioned
doses of opioids when they felt lonely. Another 26% admitted to
taking someone elses drugs on occasion.
"We dont really know the clinical significance of any one
behavior until we know more about its prevalence in a variety of
populations," Dr. Passik said.