Alternatives to oral opioids for cancer pain.

Although the optimal route of administration of opioids is by mouth, some patients may require alternative routes during the course of their illnesses for several reasons. These include bowel obstruction, severe emesis, or severe dysphagia. In these cases, the alternatives include the subcutaneous or rectal route. The transdermal route also provides a simple, comfortable method that produces stable blood drug concentrations. The high potency and lipid solubility of fentanyl make it suitable for this route of administration. Iontophoresis can provide a rapid drug delivery rate, but no clinical studies exist to document the long-term effectiveness of this method in controlling pain. The transmucosal route is recommended only for those opioids with high solubility, such as buprenorphine, the fentanyl series, and methadone. Oral transmucosal fentanyl (Actiq) provides a rapid onset of pain relief and is appropriate for treating episodes of breakthrough pain.