Pharmaceutical opioid changes risk overdose increase in New Zealand

In late 2019, a change was initiated to limit long acting (slow-release) morphine preparations available in New Zealand to one product, m-Eslon capsules. The previously funded slow-release tablets, Arrow Morphine LA, will no longer be available once existing supplies are exhausted (as of the beginning of March, both the 10mg and 100mg are no longer available). As a bioequivalent product, this should have minimal impact on patients, and indeed brings some benefits for patients, notably those with swallowing difficulties.

New Zealand has a unique and peculiar illicit drug market in that it lacks true illicit opioids; heroin is sporadically available, but is generally uncommon and not widespread. The opioid market is largely filled with diverted pharmaceutical opioids (opioid agonist treatments and analgesics) including morphine tablets. People who misuse opioids often seek to reproduce or simulate the euphoriant effects of heroin, in New Zealand this is achieved by converting morphine from these pharmaceutical preparations into a crude form of heroin by heating a crushed morphine tablet with acetic anhydride, which converts the morphine to mono- or diacetyl-morphine (heroin), depending on the skill of the ‘cook’.

m-Eslon capsules have been approved for the market in New Zealand since 2002. During this period, supplies of this formulation inevitably have reached the illicit market, but they are not quite as straightforward to convert to heroin as the tablet formulations. As a consequence, the illicit market has continued to favour the tablet product. The move to the slow-release capsule form is likely to have unintended consequences for people who misuse these drugs.

The conversion of a tablet, by the user, ensures a product of consistent quantity and dosage (it is assumed a person using the same process each time will produce a similar yield of drug consistently). As the tablet formulation becomes unavailable for the illicit market, anecdotal reports suggest that in some parts of New Zealand the content of the morphine capsules is now reaching the illicit market in the form of pre-manufactured heroin powder, in contrast to the standard pharmaceutical formulations previously traded. The conversion to heroin is being undertaken by those dealing in the market. Powdered heroin is of concern as it means that it will be harder for users to measure or gauge doses. There may be unintended consequences if batches of these products are made to varying standards, and there is a significant risk if the product is diluted, or cut for profit by unscrupulous individuals.

A shift in the availability of sought after products also lends itself to changes in drug user preference. A significant concern is that a shift to illicit powdered drugs replacing pharmaceutical formulations leaves the potential of powdered fentanyl being added to the supply chain as is commonly seen in many other Western nations with a market for heroin. Anecdotal reports suggest illicit fentanyl has recently been sold as heroin in at least one major New Zealand city. The change in the available morphine formulations could have the unintended consequence of opening the illicit opioid market for widespread fentanyl use to develop in New Zealand. The major risk posed is that of opioid overdose.

Ironically, until now, the presence of morphine tablets on the market has ensured that people are able to accurately measure their opioid intake and this is likely to have contributed to New Zealand’s relatively low overdose death rate (approximated to be between 35 and 47 deaths a year,¹ although thought to be higher²). In comparison, the overdose rate in Australia, where the illicit opioid market includes powdered heroin, is significant: 438 heroin-induced deaths in 2018³ with pharmaceutical opioids compounding these.

New Zealand is woefully underprepared for the arrival of illicit fentanyl or a shift to an illicit powdered opioid market. Naloxone availability is poor, despite legislative change in 2016 to allow its supply to those at risk.

This letter is not an argument for a return to the use of the tablet form or promote the misuse of pharmaceutical products. It intends to highlight potentially significant overdose concerns and raise awareness within the health community.