Patterns of Neonatal Co-Exposure to Gabapentin and Commonly Abused Drugs Observed in Umbilical Cord Tissue.
Gabapentin was thought to have low abuse potential, but it is increasingly being abused by people with substance use disorder in an attempt to potentiate the euphoric effects from opioids and other CNS depressants. Additionally, infants co-exposed to gabapentin and opioids during pregnancy tend to exhibit prolonged and more severe neonatal abstinence syndrome. In this study, we describe positivity rates among commonly abused drugs and rates of co-medication with gabapentin in a large dataset of umbilical cord tissue specimens (n 25,422) submitted for routine newborn drug testing at a national clinical reference laboratory (ARUP Laboratories, Salt Lake City, UT, USA). Detection of prenatal drug exposure in umbilical cord tissue specimens was accomplished using a semi-quantitative liquid chromatography-tandem mass spectrometry assay designed to detect 47 specific drugs and drug metabolites including opioids, stimulants, sedative-hypnotics and hallucinogens. A positive result for at least one of the measured drugs or drug metabolites was reported in 7,054 (28%) of the umbilical cord tissues analyzed. Gabapentin had a positivity rate of 2% with 562 positive results. Of the 562 gabapentin-positive samples, 395 (70%) also had a positive result for at least one other drug or drug metabolite, with the highest co-positivity rate observed for norbuprenorphine (32%, n 182) followed by amphetamine (15%, n 84), buprenorphine (13%, n 74), methamphetamine (12%, n 68), morphine (11%, n 64), fentanyl (10%, n 54) and naloxone (10%, n 54). Notably, the concentration of gabapentin in gabapentin-positive umbilical cord specimens was higher in buprenorphine-containing specimens as compared to specimens containing other opioids, stimulants or benzodiazepines. Identification of neonatal co-exposure to gabapentin and opioids, particularly buprenorphine, may guide clinicians in rapid initiation of monitoring and intervention for neonatal abstinence syndrome.