Opioid maintenance prescribing
Prescribing Notes
General Information
- Supervised self-administration of medication by pharmacists optimises compliance and minimises leakage into the illicit market. However, it is also important to give due consideration to the need to provide a patient-centred approach when considering requests for increased take-home doses. The capacity to supervise consumption in community pharmacy has been reduced as a consequence of the COVID-19 pandemic and should now be prioritised for patients who are initiating treatment or whose drug use remains unstable despite being maintained on an opioid substitution treatment
- Patients who miss 3 consecutive days or more of their regular prescribed dose of opioid substitution therapy are at risk of overdose because of loss of tolerance. Community pharmacists should contact the keyworker after the patient has missed 2 consecutive doses. After 3 or more missed doses the pharmacist should stop further dispensing until the patient has been reviewed by the keyworker and /or prescriber. For further information refer to ‘Opioid Substitution Treatment: NI Supplementary Guidance for Community Pharmacists’. Prescribers may wish to consider reducing/stopping opioid substitution therapy if a patients has missed more than three days. If the patient misses 5 or more days of opioid substitution therapy, an assessment of illicit drug use is also recommended before restarting substitution therapy; this is particularly important for patients taking buprenorphine because of the risk of precipitated withdrawal.
- Use methadone 1mg/ml. The stronger formulation (10mg/ml) should not be used
- Methadone tablets should not be used routinely for opioid maintenance prescribing. They are occasionally prescribed in exceptional circumstances for patients travelling abroad
- When administering Espranor®, the oral lyophilisate should be removed from the pack with dry fingers – any contact with moisture will result in disintegration of the wafer
- The route of administration for Espranor® is on the tongue (i.e. supralingual), not under it
- Prolonged Release Buprenorphine (PRB) Buvidal® Depot Injection: In Northern Ireland buprenorphine (Buvidal®) is accepted for use by specialist addiction services only for the treatment of opioid dependence within a framework of medical, social and psychological treatment. Buvidal® is administered as a prolonged-release solution for subcutaneous injection either on a weekly basis in doses of 8mg, 16mg, 24mg and 32mg or on a monthly basis in doses of 64mg, 96mg or 128mg strength. Treatment is intended for use in adults and adolescents aged 16 years or over
- Caution is required in prescribing medications for patients who attend out of hours or emergency department (ED) stating they have not had their usual supply of methadone or buprenorphine that day
- Adjunctive therapy may be required for the management of opioid withdrawal symptoms. Loperamide may be used for the control of diarrhoea; mebeverine for controlling stomach cramps; paracetamol and NSAIDs for muscular pains and headaches; metoclopramide or prochlorperazine may be useful for nausea or vomiting (see BNF for further details). Note potential for abuse with:
- Loperamide- there has been increasing usage of high doses of oral loperamide to achieve a “high” or to overcome the symptoms of opiate withdrawal. Serious cardiovascular events, including fatalities have been reported in association with large overdoses of loperamide – see MHRA
- Hyoscine – misuse of hyoscine (Buscopan®) has been reported, particularly in prisons. Crushing and smoking hyoscine releases scopolamine, a known hallucinogen. Prescribers are advised to use an alternative medication where treatment is indicated e.g. mebeverine. Refer to DH letter for further details
- All medications, in particular methadone, should be stored in a child secure area
Hospital admission of people who misuse drugs
- Good communication between hospital and community is essential for safe patient care. Patients will usually have a named keyworker and a named pharmacy. They will be receiving treatment from their own GP, a specialist GP provider, or local drug treatment services
- It is not recommended to dispense methadone or buprenorphine as ‘take home’ medicines to avoid any risk of ‘double prescribing’ – refer to local trust policy
- Drug misusers may be admitted to hospital for treatment of conditions common to other patients or directly related to their drug misuse. In either case, hospital medical staff should take proper account of any drug misuse and any treatment being provided in the community
- Pregnant women dependent on opioids should be jointly managed by their obstetrician and the OST team
Acute pain management for people who misuse drugs
- Contact the relevant pain control team for advice
- Drug misusers in pain will have needs for pharmacological and other interventions similar to non-drug users
- Acute pain requires full analgesic management in patients dependent on opioids. These patients may have a lower tolerance of pain together with a higher tolerance of opioid analgesic effects
- If pain is mild to moderate, non-opioid analgesia (as used in the general population) is the initial treatment of choice together with appropriate education and advice
- For more severe pain, if opioid analgesia is indicated, the treatment will depend on whether the patient is taking full agonist opioids such as methadone, partial agonist opioids such as buprenorphine, or opioid antagonists such as naltrexone. If the patient is dependent on full agonists the opioid pain relief should be in addition to the usual opioid treatment dose and the amount of pain relief medication titrated against pain while monitoring respiratory function. Sub-therapeutic doses should be avoided
- Splitting the dose of methadone in order to control pain is occasionally done for some patients taking methadone (e.g. from once daily to twice daily). If the patient is dependent on a partial agonist, such as buprenorphine, specialist advice should be sought but, if the buprenorphine is continued, especially high doses of full agonist opioids will be required initially, with careful monitoring and anticipated dose reduction in the subsequent 36 to 72 hours
- Opioid antagonists such as naltrexone will render opioid analgesia ineffective
- It is important to be extremely careful when prescribing additional drugs such as sedatives or gabapentinoids. It may be necessary, in some cases, to contact the relevant pain control team for further advice on improving pain control
- Chronic pain management can be complex and requires good joint working arrangements as well as specialist knowledge. Chronic pain management for patients who are receiving substitute prescribing for drug misuse is not covered in the NI Formulary; information sources include “Drug Misuse and Dependence – Guidelines on Clinical Management” (Department of Health, 2017)