Defining Key Terms in Pain Management

tolerance

Tolerance is the need for an increased dosage of a drug to produce the same level of analgesia
that previously existed. Tolerance also occurs when a reduced effect is observed with a constant
dose. Analgesic tolerance is not always evident during opioid treatment and is not addiction. (1)

pseudotolerance

Pseudotolerance is the need to increase dosage that is not due to tolerance, but due to other factors
such as: disease progression, new disease, increased physical activity, lack of compliance, change in
medication, drug interaction, addiction, and deviant behavior. When a once-fixed opioid dose is no
longer effective, the above conditions should be reviewed to exclude pseudotolerance. (2)

physical dependence

Physical dependence can be described as the occurrence of withdrawal syndromes after opioid
use is stopped or quickly decreased without titration. Physical dependence can also occur if an
antagonist is administered. It is not addiction. (1) Physical dependence "... is not a clinical problem if
patients are warned to avoid abrupt discontinuation of the drug, a tapering regimen is used
(if treatment cessation is indicated), and opioid antagonist drugs (including agonist-antagonist analgesics)
are avoided." (3)

addiction

Addiction is "psychological dependence on the use of substances for their psychic effects and is
characterized by compulsive use" (1) Addiction should be considered if patients no longer have
control over drug use and continue to use the drugs despite harm. (1,3)

pseudoaddiction

Pseudoaddiction is drug-seeking behavior that seems similar to addiction, but is due to unrelieved
pain. This behavior stops once that pain is relieved, often through an increase in opioid dose.
"Misunderstanding of this phenomenon may lead the clinician to inappropriately stigmatize the patient
with the label 'addict.' In the setting of unrelieved pain, the request for increases in drug dose requires
careful assessment, renewed efforts to manage pain, and avoidance of stigmatizing labels." (3)

References: 1. Federation of State Medical Boards of the United States, Inc. Proposed model guidelines
for the use of controlled substances in the treatment of pain. Euless, Texas: The Federation of State
Medical Boards of the United States, Inc; 1998:1-5. 2. Pappagallo M. The concept of pseudotolerance
to opioids. J Pharm Care in Pain & Symptom Control. 1998;6:95-98. 3. Cherny NI. Opioid analgesics:
comparative features and prescribing guidelines. Drugs. 1996; 51: 713-737.