The role of opioid analgesics in pain

Opioids have been recognised as having an important role in the control of pain for millennia (Rosenblum et al., 2008) initially through naturally occurring opiates found in the opium poppy, to the extraction and identification of morphine and later development of synthetic opioids such as heroin, oxycodone and tramadol. Current clinical guidance (British Medical Association, 2017; Dowell et al., 2016) offers a more conservative understanding of the role of opioids, particularly in the context of chronic pain. This represents the most common presentation for analgesia and is contrasted with pain arising from an acute injury or interventions such as a surgical procedure, or terminal cancer. In chronic pain, opioids are recognised as being one of several pharmaceutical therapies which also include non-opioid analgesics such as paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs), tricyclic antidepressants and most recently gahapentinoids (British Medical Association, 2017). Perhaps most importantly, however, is recognition of a range of non-pharmacological therapies, such as physiotherapy and psychological and cognitive behavioural therapies, which are recognised as having an important place in the overall management of chronic pain. Evidence suggests that opioids often do not have a significant or beneficial effect in the management of chronic pain despite their potency and position in the traditional analgesic ladder, particularly for the most common presentations such as lower back pain (Abdel Shaheed et al., 2016; Ballantyne & Shin, 2008; Deyo et al., 2015; Dowell et al., 2016).

It is tempting to think that such concerns and the lack of evidence of longterm efficacy would have a negative impact on opioid analgesic availability but there has actually been a well-recognised trend towards increasing prescribing of opioids globally (OECD, 2019). Some countries, such as the United States and United Kingdom, have reported more recent reductions in prescribing but concerns remain about, for example, the rise in high strength opioid analgesics (Curtis et al., 2019) and sustained release preparations. Increasing opioid prescribing has not only been attributed to increasingly older patient populations qua consumers, for whom chronic musculoskeletal pain is more common, but also to claims of pharmaceuticalisation and the undertreatment of pain (Finestone et al., 2016; Portenoy &. Foley, 1986). Pharmaceuticalisation extends the concept of médicalisation (where non-medical problems become medical ones) to include the role of the pharmaceutical industry and activities such as drug marketing and promotion to the public and prescribers (Abraham, 2010). The most well-known example relating to opioid analgesics is that of oxycodone and the pharmaceutical company Purdue who manufactured and marketed it. The company was heavily criticised for overmarketing - particularly their long-acting product Oxycontin - to undertrained primary care doctors in the United States, and also under-representing iatrogenic addiction harms (Finestone et al., 2016; Van Zee, 2009). As Finestone et al., (2016) argue, however, it is not only the inappropriate marketing activities of the pharmaceutical industry but also more systemic failures to provide adequate non-pharmacological services and resources.

Concern about the undertreatment of pain arose in the 1970s and 1980s initially in relation to palliative care (Portenoy & Foley, 1986) and clinicians’ litigation concerns regarding iatrogenic addiction. An influential campaign led to pain being considered the ‘fifth vital sign’ in the United States (Tompkins et al., 2017) which ushered in a trend in increased prescribing in the United States in particular and eventually more widely. Further contributing to the case of undertreatment of pain was the significant problem of framing pain management and to the difficulty of distinguishing between the needs of ‘genuine patients’ and others using analgesics ‘illegitimately’ (Bell &. Salmon, 2009). Analysing the existing literature, these authors argue that:

...discourses on pain management and the right to pain relief reify distinctions between the ‘deserving pain patient’ and the ‘undeserving addict’, serving both to further stigmatise people labelled as ‘addicts’ and delegitimise claims to pain they might voice.

(Bell & Salmon, 2009, p. 170)

Attempts to address concerns about opioid analgesic prescribing and use have been introduced and a variety of educational, surveillance and regulatory interventions have been attempted (Compton et al., 2015). In the United Kingdom, resources such as Opioids Aware (Faculty of Pain Medicine, 2015) were developed to provide information and advice to both prescribers and patients. Surveillance has been used particularly in countries such as the United States through prescription drug monitoring programs and even at the level of individual patient ‘doctor shopping’ (Compton et al., 2015). A variety of regulatory changes have been introduced, particularly to limit the supply of opioids. In Australia, for example, upscheduling has meant that the OTC supply of opioids such as codeine is now prohibited and restricted to prescription supply only (Roberts &. Nielsen, 2018). This resulted from recognition that compound opioid analgesic products may cause significant harm despite being less potent than prescription medicines (Frei et al., 2010). Changes in prescribing category have been addressed elsewhere. For example, in the United Kingdom, the synthetic opioid tramadol was reclassified as a Schedule 3 controlled drug some 20 years after its introduction, following concerns about increased overdose deaths (Stannard, 2019). Several years earlier, the compound analgesic co-proxamol was completely withdrawn from the market in the United Kingdom due to fatalities associated with its use (Hawton et al., 2012). In several countries including the United Kingdom, OTC opioid packaging was voluntarily changed by manufacturers to carry addiction warning messages and time limited use (Cooper, 2011; Medicines and Healthcare Products Regulatory Agency, 2009).

An ongoing concern, however, is the lack of long-term evidence of the efficacy of opioid analgesics. Despite concerns, clinical guidelines and subsequent practice still offer a place for such therapies. Central to the guidance provided to prescribers and suppliers is the recommendation of punitive surveillance strategies such as urine testing, treatment contracts, and the use of buprenorphine or take home naloxone when addiction or overdose respectively are considered a risk (Dowell et al., 2016).