Clinical realities and economic considerations: special therapeutic issues in intrathecal therapy--tolerance and addiction.

The long-term use of opioid analgesics in chronic nonmalignant pain has long been controversial. Rational discussion has been impeded by outdated research and myths regarding the risks of this therapy. Some of the misconceptions relate to the inappropriate use of the terms tolerance and addiction. Analgesic tolerance is a phenomenon in which exposure to the opioid itself causes the patient who has achieved analgesia to require a higher dosage to maintain the same level of effect. This appears to be very uncommon in the clinical setting. A need for dose escalation results from factors other than tolerance, including disease progression. Addiction is an association of psychological dependence and aberrant drug-related behaviors. Addiction to opioids in the context of pain treatment is rare in those with no history of addictive disorder. Clinicians need to become aware of the new findings regarding the low risk of addiction and tolerance in this setting.