Would opioid guidelines always work on cancer patients?The answer is NO. – 13.7% do not respond to usual doses and only half of those will get any benefit from increasing the dose. If one were to extrapolate, this would mean 7% of opioid users would need higher than usual doses of opioids to respond. I guess this is why the new rules are only suggestions and not hard and fast regulations. Now, if only College regulators could handle these implications… Opioid induced hyperalgesia might be helped by switching opioid.
Cancer Manag Res. 2019 Dec 10;11:10337-10344.
Lack of Efficacy: When Opioids Do Not Achieve Analgesia from the Beginning of Treatment in Cancer Patients.
Corli O et al
- 44 cancer centers – 520 people
started “with 30 to 60 mg daily of morphine-equivalent, on the basis of the patient’s previous analgesic therapy and generalclinical condition”
- lack of analgesic response was determined after 3 days of treatment
- the dose [in responders] was in average 49.7 mg/daily that after 3 days was homogeneously increased about 50% in ENRs[non-responders] – so maybe 100 mg
- This would be above the opioid 90 mg limit suggested.
Reasons for higher need?
- fast metabolizers – they suggested blood opioid levels might shed a light on that
- “desensitization, internalization, and down-regulation of opioid receptors” which can occur quickly in some
- Opioid-induced-hyperalgesia – occasional pro-nociceptive process by effects of opioids on N-methyl-D-aspartate (NMDA) receptors – interestingly this effect was often negated by switching to another opioid :
“The types of response changed after 7 days of treatment, with 31.7% of the patients who remained NRs [nonresponders], experiencing a worsening of API – ; 48.3% switched and became Rs[responders], with a drastic API reduction (about 60%), and 20.0% experienced only modest pain-relief”
Comment – many years ago I saw a presentation where they showed 100 mice lines with differing sensitivities to opioids – some needing little, and some unresponsive – put into a spectrum of responsiveness. Denying needs for excessive opioid would require access to their genetic sensitivity to opioids which is not available at this time. Even in undeniable pain cases (cancer) not all subjects will meet guideline suggestions. Worsening or unresponsiveness might be helped by switching opioid (despite how might fentanyl is hated now -that might be an option)