Gaps and junctions between clinical experience and theoretical framework in the use of opioids

Management of breakthrough pain in patients with cancer

Breakthrough pain (BTP) in patients with cancer lacks a consensus definition and is subsequently inadequately diagnosed and assessed, therefore making it more challenging to manage. Cancer pain is generally moderate to severe in intensity and persistent in nature. Despite the problematic definition of BTP, it is generally described as having similar intensity, but may also be transitory and variable in predictability. Most breakthrough analgesia fails to be effective in the time required for BTP. No useful analgesia is therefore provided but drug adverse effects escalate. Cancer pain management relies on the WHO analgesic ladder. The frequency of BTP and its inadequate management means that it has significant adverse effects on patients, their families and those involved in their care. This article outlines a systematic, clinical and evidence-based approach to managing BTP in patients with cancer that emphasizes a holistic approach and an understanding of multidimensional 'total pain'. Guidelines for managing BTP are presented and areas of developing research are identified.

Diagnose und Therapie von tumorbedingten Schmerzen

The World Health Organization guidelines for cancer pain therapy from 1986 are still valid. A prerequisite for adequate pain palliation is an exact anamnesis and pain diagnosis. A multimodal, staged therapeutic concept then needs to be formulated according to the requirements of the patient. The pharmacological treatment starts with non-opioids. If pain control remains insufficient, weak opioids are added. In case of persistent pain these are replaced by strong opioids. The availability of new opioids and/or preparations admits a more sophisticated approach to metabolic disorders and specific pain syndromes. Depending on the presenting pain type, co-analgesics might be added.

Controversies in pharmacotherapy of pain management

Since the establishment of the WHO three-step ladder for management of cancer pain, several controversies have arisen, which are partly due to new drug development, reformulations of older analgesics, and technological advancements. As a result, clinicians need clarification of several questions. Is morphine the opioid of choice for moderate to severe pain in cancer? Should combinations of opioids be used? When should spinal opioids be used to treat pain in cancer? What are the appropriate opioid doses for breakthrough pain? Should selective cyclo-oxygenase (COX) 2 inhibitors be used? What is the best tactic to treat neuropathic pain, and what first-line adjuvant analgesic should be used? And do bisphosphonates relieve bone pain in cancers other than breast cancer and myeloma? This review addresses these questions.

Look before leaping: combined opioids may not be the rave

The use of combinations of potent opioids is a common clinical practice. The addition of one potent opioid to another has been recommended to reduce opioid side effects, improve pain control, and limit dose escalation of the first opioid. The advantages of using combined opioids have been reported to be relative to differences in receptor activation versus endocytosis (RAVE). However, the advantages and detriment to combining opioids are related to naturally occurring opioid receptor dimers. Dimers and oligomers result in a unique opioid pharmacodynamics which influence opioid binding, G protein interactions, desensitization, receptor trafficking, and endocytosis. The pharmacodynamics of dimers may lead to positive or negative cooperativity when two opioids are combined. The use of multiple opioids in practice can lead to increased risk for dosing errors, reduced patient compliance, increased drug interactions and cost. Opioid combinations should not be used until prospective randomized trials clarify the benefits and safety.

[Treatment of chronic pain in the internist's practice]

Chronic pain is one of the most frequent complaints in outclinic supply. Careful anamnesis and physical examination are in the focus of diagnostic procedure. Their results will give strong evidence for the underlying pathogenesis. Nevertheless, the perception of pain remains completely subjective and can be only measured by asking the patient. Therefore, a multitude of validated instruments has been developed ranging from the simple intensity rating scales up to sophisticated questionnaires. Both, the diagnostic and therapeutic procedures should adhere to the bio-psycho-social concept of pain. Medical treatment should be executed in accordance to the WHO Guidelines for Cancer Pain Treatment. But for the majority of patients, multidisciplinary concepts are required including psychotherapy and iatrophysics.