Complications in the Pharmacologic Approach of Pain

This chapter focuses on pharmacokinetics and pharmacodynamics of analgesics and the appropriate use of oral, intranasal, transmucosal, transdermal, subcutaneous, intravenous, or subcutaneous and intrathecal analgesics and co-analgesics in strict relation with their indications and contraindications of their use, and when and how to switch toward interventional or non-pharmacologic pain management to avoid these complications. In the case of a pharmacologic approach for the treatment of pain, specific basic principles should be respected in all cases. First, always select the best possible treatment that best fits the patient and the possible mechanism causing the pain. Second, always make a selection of the adequate mode of administration for a specific drug. Third, always use a clear treatment algorithm such as the World Health Organization pain ladder for cancer pain including the fourth step of invasive pain treatment. Finally, always use a fixed-rate dosing regimen with escape medication.