The Use of Parenteral Opioids in Cancer Pain Management

SIMPLE SUMMARY: There are some clinical circumstances that require the parenteral administration of opioids, as an alternative to the oral route. A parenteral route of administration is often indicated in patients with severe pain intensity requiring rapid analgesia or in those who develop nausea and vomiting, dysphagia, or have limited intestinal surface for drug absorption. Subcutaneous and intravenous routes are effective in providing rapid analgesia, particularly the intravenous route. Many opioids have proved to be effective when administered in clinical conditions where oral opioids cannot be used or are poorly effective. Although most studies on this topic are not controlled, there is a body of experience suggesting that parenteral opioids may be useful in some specific circumstances. ABSTRACT: Opioids should be offered to patients with moderate-to-severe pain related to cancer or active cancer treatment unless contraindicated. Although oral administration of opioids is generally preferable, a parenteral route may be advisable and mandatory in some clinical circumstances. Parenteral administration of opioids may accelerate the achievement of analgesia. The intravenous route fits the need of rapid achievement of analgesia in patients poorly responsive to other opioids and provides a fast analgesia in patients with breakthrough pain, that has a specific temporal pattern requiring a rapid analgesic effect. When the oral route is unavailable for the presence of nausea, vomiting, or dysphagia. the parenteral route is one of the principal options. Opioids have different pharmacokinetic and pharmacodynamic characteristics and should be chosen according to the individual needs. Thus, the knowledge and experience with these routes of administration are mandatory for anesthesiologists committed to cancer pain management.