Tolerance of Opiates and Escalation of Effective Dosage
"During long-term treatment, the effective opioid dose can remain constant for prolonged periods. Some patients need intermittent dose escalation, typically in the setting of physical changes that suggest an increase in the pain (eg, progressive neoplasm). Fear of tolerance should not inhibit appropriate early, aggressive use of an opioid. If a previously adequate dose becomes inadequate, that dose must usually be increased by 30 to 100% to control pain."
"Treatment of Pain." The Merck Manual for Health Professionals. Merck & Co. Inc. Last accessed April 6, 2013.