Neonatal abstinence syndrome: comparing the hepatic metabolism of addictive medicines in vitro in the fetus, neonate and adult female
abstinence syndrome (NAS) is defined as neonatal withdrawal symptoms due to antepartum
maternal substance abuse. Substances that are most likely to cause NAS are opioids,
alcohol and central nervous system (CNS) stimulants or depressants, such as cocaine and
benzodiazepines, respectively. Opioid addiction in adults as well as neonates is treated
with methadone or buprenorph... read moreine. In severe maternal addiction and neonatal withdrawal
cases, morphine is administered as an additive to methadone or buprenorphine. Mothers
who are on methadone or buprenorphine treatment are often found to have plasma traces of
alprazolam, a common benzodiazepine prescribed for the treatment of anxiety. However,
the in vitro metabolism of these drugs, either alone or when taken together, has never
been well established in fetuses or neonates. Here, we analyze the activity of
methadone, buprenorphine, morphine, and alprazolam in fetal, neonate and adult female
livers. Since the cytochrome P450 3A enzymes (CYP3A4 and CYPA5) are common and major
routes of metabolism for these drugs, the resulting metabolite of each can be measured
to assess the activity. This was done by in vitro incubations with human liver
microsomes (HLM) from adult females (20-75 years old) and neonates (male and female, 13
days - 11 months old). The metabolites were identified by high-performance liquid
chromatography (HPLC). We found there was no significant difference in alprazolam,
buprenorphine or methadone metabolite formation rate between adults and neonates.
Morphine showed inhibition of alprazolam metabolite formation at high concentrations in
both female adult and neonatal liver microsomes. We also saw high variability between
the individual microsomes and performed a multiple linear regression analysis to
determine if age, CYP content, and alcohol or cigarette use could be responsible for
this variability. From these analyses, CYP content was a significant variable for
predicting metabolite formation in all groups except neonates in 4-hydroxyalprazolam
(4-OHALP) and 2-ethylidene-1,5-dimethyl-3,3-dipehnylpyrrolidine (EDDP) production.
Additionally, norbuprenorphine (NBUP) and EDDP formation rate was partially related to
alcohol use in adult females. From these results, we can conclude: 1) the metabolite
formation rate differences of 4-OHALP, BUP, and EDDP between adult females and neonates
are not predictors of neonatal abstinence syndrome onset, but in vitro studies with
fetal microsomes still need to be done and 2) the interaction between morphine and
alprazolam occurs at a concentration too high to be of pharmacokinetic importance, but
there may be an underlying pharmacodynamic mechanism leading to additive
Thesis (M.S.)--Tufts University, 2018.
Submitted to the Dept. of Pharmacology and Drug Development.
Advisor: David Greenblatt.
Keyword: Pharmacology.read less