Webinar: Safe and effective prescribing of strong opioids for advanced cancer pain Q+A

Questions and answers that were not addressed in the webinar

How do you decide on the starting dose of morphine? Age/pain score/renal function?

When deciding on the starting dose of morphine, it is necessary to consider the individual circumstances, e.g. severity of the pain, current analgesia, presence of renal impairment, increasing age or frailty. In every case, the patient must be monitored closely, and the dose titrated as necessary. Detailed guidance, including suggested starting doses of morphine, via oral or subcutaneous routes, is available in the PCF Morphine monograph for patients who:

• Have been previously taking weak opioids.
• Are frail, elderly or opioid naïve.
• Have renal impairment.

Will the ratios between opioids be the same for low (i.e. starting doses) as for higher doses, for example morphine 120–200 mg/day? What would be the recommended dose of oxycodone? What other factors have to be taken into consideration?

PCF recommends consistency in the use of conversion ratios and that local guidelines should be followed. As discussed in the webinar, opioid dose conversion ratios are only ever an approximate guide, and patient circumstances must always be taken into account to derive an appropriate starting dose.

Rather than using different ratios for different opioid dose ranges, a dose reduction of the calculated initial dose of the new opioid may be appropriate. Switching at higher doses requires extra care and a reduction of 25–50% from the calculated dose, taking into account other co-existing factors (see below), may be prudent, especially if there has been a rapid escalation of the first opioid. In such circumstances, p.r.n. doses can be used to make up any deficit while re-titrating to a satisfactory dose of the new opioid.

Factors to consider when determining the dose include:

• Whether the patient’s pain is currently adequately managed.
• Whether the patient has any concerning opioid undesirable effects such as neurotoxicity (significant drowsiness, confusion, hallucinations) or respiratory impairment.
• Whether the patient has renal or hepatic impairment, or sepsis and whether the clinical situation is stable or unstable.
• Whether the patient is frail, has other comorbidities or is taking other medications.
• Environment: will the opioid switching be carried out in hospital, palliative care unit or in the patient’s home and what degree of monitoring is available.
• Experience of the team and people caring for the patient in terms of use (prescribing, monitoring, titrating) of different opioids.

Close monitoring of the patient is recommended. The PCF Strong opioids monograph (switching section) and Opioid dose conversion ratios appendix gives detailed information on the ratios to use and factors to take into consideration.

Are you aware of any UK based guidelines on the management of patients with an opioid use disorder maintained on methadone or buprenorphine who are also under the care of palliative care team?

The PCF Strong opioids monograph (psychological dependence section) summarizes and references the available information for the use of strong opioids in patients with substance abuse.

Any prescribing advice for patients with a prior opioid addiction and/or fear of developing one?

Risk factors for opioid addiction are detailed in the PCF Strong opioids monograph and reference is made to screening tools which may be of use. PCF recommends caution when prescribing opioids for patients with a present or past history of substance abuse. However, opioids should be used if there is a clinical need.

Do we have to prescribe insulin in patients on end of life care?

This question is out of scope of this webinar which is on the safe and effective prescribing of strong opioids for advanced cancer pain. However, PCF Drugs for diabetes monograph contains detailed information on the management of patients with diabetes in the last few weeks of life.