In general, most addicts like to use drugs that have high potency or fast onset of action. Therefore, the controlled release drugs like Transdermal fentanyl have the lowest abuse potential. Oral controlled release opioids like Oxycontin can be crushed to destroy the matrix and they become the equivalent to immediate release forms. The most common side effect of chronic opioid therapy is constipation secondary to decreased gastrointestinal motility. However, concerns about potential cognitive impairment are more often the reason opioids are not prescribed, particularly in the elderly.
Elderly patients are more susceptible to delirium than younger patients.
Although no studies have examined this risk of delirium in chronic pain syndromes treated with opioids, post-operative patients are less likely to develop cognitive impairment with fentanyl than morphine. A similar study found that cognitive performance was poorer in patients receiving hydromorphone compared to those receiving morphine. Many metabolites of opioids are excreted by the kidney increasing toxicity in the elderly. Creatinine clearance should be monitored to minimize potential toxicity. No treatment should be continued without benefit.