The management of opioid dependence during pregnancy in rural and remote settings

What are the patterns of opioid dependence in rural and remote areas of Canada?

Statistics Canada defines a rural community as having less than 10 000 people, with less than 30% of the population commuting to a city of 100 000 people or more for work.8 However, the Canadian Medical Association defines rural as areas in which physicians have high call requirements, there are long distances to secondary and tertiary care centres, there is a lack of specialist care and there are insufficient health care providers.9

Given these differing definitions, the descriptions of pregnant women with opioid dependence who reside in these areas vary widely in terms of socioeconomic status, ethnic diversity and proximity to urban resources.10 Heroin is the most commonly reported opioid used by pregnant women living in rural and remote communities,2^,10^,11 but the nonmedical use of prescription opioids is increasing.10^,11 Regardless of the opioid in use, treatment strategies for pregnant women in these communities primarily involve methadone maintenance.2^,3

What is the recommended treatment for opioid dependence during pregnancy?

The management of opioid dependence in pregnancy in rural and remote settings requires special consideration (Boxes 2 and 3).

Methadone maintenance therapy is the gold standard for treating opioid dependence in pregnancy.12^,13 Numerous studies have shown that, in pregnant women who use heroin, methadone is associated with more visits for antenatal care, longer gestations, higher birth weights, lower rates of HIV infection, higher rates of infant discharge home in care of the mother and lower rates of relapse compared with no treatment or detoxification.4^,5

Methadone has important logistical limitations that prohibit its use in resource-limited locations. Methadone can only be prescribed by physicians who hold a special license.14 Because of the high risk of overdose at the start of treatment, methadone must be dispensed daily and ingested under the observation of a licensed pharmacist at a registered pharmacy.15 Because many rural and remote communities are unable to provide this service, methadone is not offered.

What are the alternatives to methadone maintenance therapy?

Observational studies have shown buprenorphine maintenance therapy to be a safe and efficacious alternative to methadone for the treatment of opioid dependence in pregnant women.16^,17 Recent randomized controlled trials have shown that buprenorphine and methadone cause similar reductions in maternal opioid use and similar birth and neonatal outcomes, and that buprenorphine is associated with decreased severity of symptoms of neonatal abstinence syndrome.18^,19 A case series describing 10 women who took buprenorphine plus naloxone maintenance therapy showed outcomes similar to those of buprenorphine alone.20

Buprenorphine is a partial μ-opioid receptor agonist that has a lower risk of fatal overdose than full μ-opioid agonists such as methadone. Buprenorphine may precipitate withdrawal if caution is not exercised at the start of treatment. The drug may also incompletely treat withdrawal symptoms, putting patients at risk for ongoing use of illicit drugs to manage their symptoms. Furthermore, buprenorphine may be less effective than methadone at retaining patients in treatment if they used opioids intravenously.21^,22 Unlike methadone, Health Canada does not require an exemption to prescribe buprenorphine; however, outside of Ontario and Quebec, public funding of buprenorphine is restricted to physicians with a methadone license.23

The buprenorphine formulation now includes naloxone, which is intended to deter misuse. Addiction literature often cites naloxone as a possible teratogen and warns against its use in pregnancy.24 However, the United States Food and Drug Administration classifies naloxone as a pregnancy category B drug, meaning that there have been no reports of teratogenicity in humans or animals.25 The greater concern in pregnant women with opioid dependence is naloxone’s ability to precipitate withdrawal if taken intravenously or intranasally. Naloxone has minimal buccal or sublingual absorption.26^,27 As previously described, acute opioid withdrawal is associated with morbidity for both the woman and her fetus.

What if methadone and buprenorphine are not available?

Slow-release morphine maintenance therapy has been proposed as an alternative to methadone when the latter is not available.28 In resource-limited areas, slow-release morphine may be more accessible because a special license to prescribe it is not required, and it is readily available in pharmacies. Accessibility is also the most notable drawback of morphine because it is more easily acquired and diverted than methadone. In addition, morphine is more easily injected than methadone, and it cannot be distinguished from heroin in a urine screening, limiting the usefulness of urine screens during treatment.

We identified one prospective, randomized study that compared methadone with slow-release morphine maintenance that included 24 women in each arm.29 No difference in neonatal outcomes, including neonatal abstinence syndrome, was seen between the two groups. Mothers taking slow-release morphine had a significant decrease in the use of benzodiazepines and other opiates. Two smaller observational studies showed that pregnant women taking slow-release morphine were significantly less likely to use benzodiazepines or additional opioids while undergoing treatment.30^,31 A hypothesized advantage of morphine is a decreased duration of neonatal abstinence syndrome owing to its shorter half-life compared with methadone.30

Is neonatal abstinence syndrome a problem?

Neonatal abstinence syndrome has not been associated with long-term neurodevelopmental harms in children, whereas ongoing maternal substance use is associated with poor developmental outcomes in children.32 The syndrome is time-limited as the infant withdraws from in utero exposure to an opioid. No association has been found between a mother’s methadone dose and the severity of symptoms of neonatal abstinence syndrome.33^,34 Furthermore, pharmacodynamic studies show that escalations in dose are needed to maintain the therapeutic effect as pregnancy progresses owing to changes in methadone metabolism.35

Is there a role for detoxification in pregnancy?

An early observational study showed similar outcomes among pregnant women who used heroin and had undergone medical detoxification compared with a control group consisting of pregnant women with no opioid dependency.36 However, medical detoxification was deemed a failure because of its inability to provide durable abstinence. This study was contrasted by two early case reports documenting adverse pregnancy outcomes in women undergoing acute heroin withdrawal rather than medically managed detoxification.37^,38 This contrasting evidence led to a resurgence of interest in medical detoxification in pregnancy in the 1990s. Complete opioid detoxification was recommended in a 2002 publication, with the aim of eliminating neonatal abstinence syndrome.39

Among the five retrospective case series involving women with heroin addiction, there is no consensus on the rate of methadone taper or the superiority of inpatient versus outpatient detoxification (Box 4).40^–44 Although the literature cites concerns for increased rates of miscarriage with detoxification during the first trimester and increased rates of preterm labour with detoxification during the third trimester,45^,46 this effect was not shown.40^,43 Neonatal outcomes, when reported, were inconsistent. In addition, maternal heroin use postpartum and ongoing addiction treatment postpartum were not reported.

We recommend that acute detoxification in pregnancy should be abandoned, given the evidence, with the exception of women who decline opioid substitution therapy. In this circumstance, a woman should be given the opportunity to transfer into an opioid substitution program at any time if she elects to do so or if she is unable to successfully taper off of opioids. Postpartum rehabilitation services must be provided for all women, particularly those who have chosen abstinence.

How does opioid dependence in pregnancy affect rural or remote Aboriginal populations?

Canada’s Aboriginal communities are predominantly in rural and remote areas and are disproportionately affected by opioid dependence, with rates between 50% and 80%.47 Nonmedical use of prescription opioids is more common than heroin use,47^,48 and the route of exposure is more often oral than intravenous.48 A 2012 descriptive report from Northwestern Ontario questioned whether the benefits seen with methadone in people who use heroin are applicable in remote Aboriginal communities where women engage in binge use of prescription opioids owing to intermittent drug availability rather than daily use of heroin.49 No evidence supports or refutes this claim.

A prevalence study involving First Nations women receiving antenatal care in Sioux Lookout, Ontario, showed that opioid use increased from 8% to 18% during the 18-month study. Neonatal abstinence syndrome in infants exposed to opioids was 30% overall and 66% among infants born to women who used opioids daily.48 Of the children affected, only 7% required pharmacologic treatment, whereas the remainder received supportive care.48 Pilot studies are in progress in First Nations communities in Northwestern Ontario to investigate community-based provision of buprenorphine maintenance therapy where methadone is not available50 and to provide locally trained maternal support workers for women with opioid dependence during pregnancy and continuing until the child reaches 3 years of age.51

Conclusion

Although methadone is the gold standard for treatment of opioid dependency in pregnancy, methadone therapy is often not feasible in rural and remote settings. Proposed alternatives to methadone, such as opioid detoxification and slow-release morphine substitution, have limited evidence to support their use in pregnancy. Stronger evidence exists to support buprenorphine maintenance therapy.

A fundamental flaw of each study is the choice of birth as an end point. This enables reporting of nominal success rates in terms of abstinence at the time of delivery and neonatal abstinence syndrome. However, the true end point is either sustained abstinence or stable opioid substitution therapy that would enable the new mother to parent her child. In this regard, the literature suggests that postpartum treatment is generally not provided to women in rural and remote communities, which contributes to high rates of relapse and apprehension of infants into custody.2^,13^,44

Despite knowledge of harm and rising rates of opioid dependence in pregnancy, there is a paucity of high-quality evidence in this area and none that specifically addresses the needs of rural and remote communities or Aboriginal communities, polysubstance use or postpartum management. There is an overwhelming need for training in opioid dependence therapy, regulatory changes to ensure pregnant women have access to appropriate medications and greater access to comprehensive treatment both during pregnancy and postpartum in rural and remote settings.

• Nonmedical use of prescription opioids during pregnancy is becoming more common, and members of Canada’s Aboriginal population are disproportionately affected.

• Methadone maintenance therapy has logistic limitations in rural and remote settings, but buprenorphine and slow-release morphine maintenance therapies are feasible alternatives.

• Opioid detoxification in pregnancy is associated with high rates of relapse and should only be offered if a comprehensive rehabilitation program is available.

• Treatment of opioid dependence and rehabilitation services should be provided to all women during pregnancy and the postpartum period.