Multimodal analgesia is the administration of two or more drugs that act by different mechanisms (via the same or different routes) to provide analgesia. This allows for lower doses of individual drugs. It combines different analgesics that act by different mechanisms and at different sites in the nervous system. The aim is to achieve greater analgesia than each of the individual drugs could provide alone and to reduce the patient's opioid requirements and any related side effects (Polomano et al. [141], Rosero and Goshi [161]).

Opioids, non‐opioids (such as paracetamol, NSAIDs, and cyclooxygenase‐2‐selective inhibitors (COX‐2)), local anaesthetics and anticonvulsants are all examples of drugs that may be used as part of a multimodal analgesic approach. An example of multimodal analgesia to manage acute post‐operative pain would be a continuous epidural infusion of a combined opioid and local anaesthetic solution along with paracetamol and an NSAID (if not contraindicated). Another example would be a continuous peripheral nerve block with paracetamol and a NSAID. Both of these approaches combine different analgesic compounds and analgesic approaches (oral route, epidural route and peripheral nerve block).

A multimodal approach may also include non‐pharmacological approaches, such as relaxation therapy, guided imagery, transcutaneous electrical nerve stimulation (TENS) and heat therapy. During the process of devising a multimodal analgesic plan, it is good practice for the prescriber to be aware of any Medicines and Healthcare products Regulatory Agency alerts that may influence their prescribing and management strategy (see https://www.gov.uk/government/organisations/medicines‐and‐healthcare‐products‐regulatory‐agency).

It has been suggested that despite progress in pain management, chronic non‐cancer pain still represents a clinical challenge, with data demonstrating that chronic pain affects between one‐third and one‐half of the population of the UK – a figure that is likely to increase further, with time, in line with the ageing of the population (Fayaz et al. [56]). Chronic pain has negative impacts on quality of life, interferes with work and causes increased mortality (Moore et al. [117]).

The management of pain is directed by the ‘analgesic ladder’ (also known as the ‘pain ladder’), which was published by the World Health Organization (WHO) in 1986 as a guide to the management of persistent cancer pain (Figure 10.6). Although the analgesic ladder was originally published for the management of cancer pain, it is now widely used by medical professionals for the management of all types of pain, including chronic persistent non‐cancer pain (Balding [6]). It involves a stepwise approach to the use of analgesics, including non‐opioids (step 1), opioids for mild to moderate pain (step 2) and opioids for moderate to severe pain (step 3). Adjuvant drugs are those that contribute to pain relief but are not primarily indicated for pain management. They can be used at all steps of the ladder. Examples include antidepressant and anticonvulsant drugs, corticosteroids, benzodiazepines, antispasmodics and bisphosphonates.

The WHO treatment guide recommends the following five points for the correct use of analgesics (WHO [195]):

Some patients who present with severe pain will need to start on step 3 of the ladder; it is frequently not appropriate for patients to progress through each step in these circumstance. Raffa and Pergolizzi ([146]) discuss how adaptations could potentially be made to the WHO analgesia ladder due to advancements that have been made in the basic science around pain anatomy and physiology, advancements in the breadth of therapeutic treatments available, and a societal shift that has occurred in attitudes toward pain management. They note, however, that it is still a useful construct in devising a pain management strategy, as it provides a series of review points in a clinician's ongoing assessment, although they caution that it should not act as a substitute for evidence‐based guidelines. Carlson ([34]) supported the use of the WHO analgesics ladder, indicating that at least 20% and potentially 100% of patients with cancer pain can be provided with adequate pain relief across the span of their illness, via the application of the WHO's guidelines.

It is important to remember that each patient will experience different types of pain, and individual patients may experience various types of pain, due to aetiological and physiological differences. Each pain needs to be assessed separately, since an individual's pain may need to be managed in various ways and one analgesic intervention or route will rarely be sufficient. Often the best practice is to combine different types of analgesia in order to achieve maximum pain control (Table 10.2). It is also important to use non‐pharmacological interventions at all stages of the treatment plan. And, finally, accurate ongoing assessment is imperative for efficient and effective pain control.

The analgesic ladder (see Figure 10.6) was designed as a framework for the pharmacological management of cancer pain and is also often used to manage chronic pain. There are several pharmacological agents available to manage pain and the analgesic ladder allows the flexibility to choose from this range according to the patient's requirements and tolerance. In 2010, new guidance on the analgesic ladder promoted its bidirectional use with a ‘step up, step down’ approach, proposing an upward pathway for the treatment of cancer pain and a downward pathway for the treatment of intense acute pain, uncontrolled chronic pain and breakthrough pain (Vargas‐Schaffer [186]).

For acute pain management, the WHO ladder can be used as a guide in reverse, starting at step 3 for immediate post‐operative pain and moving down through step 2 and then step 1 as post‐operative pain improves.

The principles of the WHO analgesic ladder are to provide a therapeutic effect alongside all other interventions (both pharmacological and non‐pharmacological), to guide the patient's treatment and help in managing their underlying condition, to prevent avoidable complications, and to maintain or improve quality of life (Vargas‐Schaffer and Cogan [187]).