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Cancer pain management: Adjuvant analgesics (coanalgesics)

Russell K Portenoy, MD
Ebtesam Ahmed, PharmD, MS
Yair Y Keilson, MD
Section Editor
Janet Abrahm, MD
Deputy Editor
Diane MF Savarese, MD


Opioid therapy is the first-line approach for moderate or severe pain in populations with active cancer. If opioid therapy by itself yields a good outcome (satisfactory analgesia and tolerable side effects) additional interventions for pain are not needed. Should the patient demonstrate a poor response to the opioid, however, therapy must be changed. This common scenario may be addressed in many ways, among which is the addition of another analgesic drug. In some cases, the use of a nonopioid analgesic, such as acetaminophen (paracetamol) or a nonsteroidal antiinflammatory drug (NSAIDs), is sufficient. In others, significant benefit may be obtained by the addition of a so-called “adjuvant analgesic” or coanalgesic. This topic review will cover the use of adjuvant analgesics in cancer pain management. Assessment of cancer pain, a review of specific cancer pain syndromes, clinical use and side effects of opioid analgesics, use of acetaminophen and NSAIDs in patients with cancer pain, and nonpharmacologic methods of cancer pain management are covered elsewhere. (See "Cancer pain management: General principles and risk management for patients receiving opioids", section on 'General principles of pain management' and "Cancer pain management with opioids: Optimizing analgesia" and "Cancer pain management: Use of acetaminophen and nonsteroidal antiinflammatory drugs".)


The term “adjuvant analgesic” was originally coined to refer to a small number of drugs that were marketed for indications other than pain but were found to be potentially useful as analgesics in patients receiving opioid therapy. Over the past three decades, the number, diversity, and uses of these drugs have increased dramatically, and several are now indicated as first-line therapy for certain types of pain [1]. As a result, the term “adjuvant analgesic” has become somewhat of a misnomer, but it is still commonly applied in the context of cancer pain. The term is used interchangeably with the term “coanalgesic” and can be used to denote any drug with a major clinical use other than pain that is used as an analgesic in selected circumstances.

Integration into cancer pain management — In the 1980s, the World Health Organization (WHO) described an “analgesic ladder” approach to the use of drugs for cancer pain (figure 1) [2]. This influential model included references to adjuvant drugs that may be used to provide additional analgesia, treat a side effects, or manage a coexisting symptom. Specifically:

Step 1 of the analgesic ladder approach, which is appropriate for mild to moderate cancer-related pain, suggests the use of acetaminophen or a nonsteroidal antiinflammatory drug (NSAID), combined, if needed, with an adjuvant drug.

Step 2, which is appropriate for moderate cancer-related pain and pain that has not responded to step 1 drugs, includes the use of an opioid conventionally used for moderate pain, plus an adjuvant drug if needed.

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Literature review current through: Nov 2017. | This topic last updated: Dec 11, 2017.
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