Rates of Fetal Polydrug Exposures in Methadone-Maintained Pregnancies from a High-Risk Population

Abstract

Methadone maintenance treatment (MMT) is the standard of care during pregnancy for opioid-dependency, showing efficacy in improving prenatal care and reducing risk of relapse. By design, however, MMT is only intended to prevent withdrawal thus facilitating cognitive behavioural interventions. In order to maximize the benefits of MMT, it is essential that methadone is both properly prescribed and that additional addiction treatment is concurrently administered. This study aims to determine the effectiveness of MMT engagement in high-risk pregnant women in reducing polydrug use by objective laboratory examination of neonatal meconium. Patients and MethodsOver a 29-month period, the Motherisk Laboratory at the Hospital for Sick Children in Toronto analyzed meconium samples as per request by social services and hospitals for drugs of abuse.ResultsOf the 904 meconium samples received, 273 were tested for methadone with 164 positive and 109 negative for methadone. Almost half of the methadone positive samples (46.34%) were also positive for at least one other opioid compound, which did not differ statistically from the methadone-negative control samples (46.79%; Chi square test, p=0.94). No differences were found between the methadone positive and negative groups in rates of concurrent amphetamines, cocaine, cannabis, and alcohol use indicating a similar risk of polydrug use between pregnant women taking or not taking methadone in this population. DiscussionThe high rates of additional opioid and other drug use in the MMT group, suggest that MMT is failing this population of patients. It is possible that methadone doses during pregnancy are not appropriately adjusted for changes in pharmacokinetic parameters (e.g. blood volume, renal function) during the second and third trimesters. This may result in sub-therapeutic dosing creating withdrawal symptoms leading to additional substance use. Alternatively, these results may be demonstrating a substantial lack in delivery of addiction support services in this vulnerable population.

Methadone or buprenorphine? The choice of substitution therapy in pregnant opioid dependent women

“…In the first years of life of children born to women who had been treated with methadone, there was an observed increase in the number of microcephaly incidents, visual abnormalities (including strabismus and nystagmus), increased blood pressure and acute or chronic otitis media [27]. It is however difficult to conclude that these incidents are only due to the effect of methadone as patients break abstinence and often take, in addition to methadone also other opioids, as well other psychoactive substances [28]. Despite this, correctly used methadone is considered relatively safe for the fetus.…”

“…W pierwszych latach życia u dzieci, których matki były leczone podczas ciąży metadonem, obserwowano zwiększoną liczbę przypadków małogłowia, zaburzeń wzroku (w tym zeza i oczopląsu), podwyższonego ciśnienia krwi, ostrego i przewlekłego zakażenia ucha środkowego [27]. Trudno jednak stwierdzić, czy opisywane przypadki to jedynie wpływ działania metadonu, ponieważ pacjentki, łamiąc abstynencję, przyjmują zwykle, poza metadonem i innymi opioidami, różne substancje psychoaktywne [28]. Pomimo tego właściwie stosowany metadon jest uważany za stosunkowo bezpieczny dla płodu.…”

“…However, in infants whose mothers had received methadone therapy, a reduction of the lateral brain ventricles and head circumference were noted during the first months of life [40]. Of course, it is difficult to conclude whether the application of methadone or other psychoactive substances taken by the dependent patients prior to and during methadone substitution therapy were responsible for the observed changes [28].…”

Cognitive function of youths born to mothers with opioid and poly-substance abuse problems during pregnancy

“…Because poly-drug use is a common feature of opioid use and is common for people on opioid maintenance treatment (Delano, Gareri, & Koren, 2013), most clinical studies of prenatal opioid exposure include persons who use a wide variety of drugs.…”

Schwangerenbetreuung bei Drogenkonsum

“…ein Drittel der mit Methadon substituierten Mütter noch mindestens ein weiteres Opioid beikonsumiert hatten. Dies bedeutet für die Schwangerenvorsorge eine Risikoerhöhung für den Feten durch die potenzierte Drogenexposition und schwankende Opiatspiegel [ 69 ] . Ein Abdosieren von Substitutionsmedikamenten oder die Neueinstellung mit Buprenorphin bei Schwangeren wird deshalb von einzelnen Autoren mit der Begründung eines erhöhten maternalen Beikonsumrisikos und der Begünstigung eines intrauterinen Abstinenzsyndroms abgelehnt [ 70 ] .…”