PLEANARY LESSON

DRUG ABUSE'S SMALLEST VICTIMS: IN UTERO DRUG EXPOSURE

M.A. Huestis
Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21124, USA (mhuestis@intra.nida.nih.gov).

The social and economic impact of drug use on our global population continues to increase leaving no geographical, social or cultural group untouched. Substance abuse during pregnancy is no exception. In 1992, the National Institute on Drug Abuse, in one of the few surveys of maternal drug abuse, found that almost half of US women of childbearing potential have used drugs at least once in their lifetime. In this self-report survey of past year drug use, cocaine and marijuana use were acknowledged by 6 and 2 million women, respectively. The mothers of 5.5% of the babies born in 1992 reported taking an illicit substance during gestation. These figures certainly underestimate the problem due to the stigma attached to drug use during gestation and to the accompanying legal, ethical and economic issues. Although the drugs of choice and routes of administration vary from country to country, exposure of our most valuable resource, our children, to the harmful developmental effects of drugs is a problem of staggering proportion with a worldwide female population of almost 3 billion. In utero drug exposure can severely impact fetal and later stages of child development. Fetal effects include decreased birth weight, length and head circumference, and impairment of normal brain development. Anyone observing a child suffering from neonatal abstinence syndrome knows the devastating effect of in utero drug exposure. This syndrome is characterized by increased startle reflex, tremors, poor self-quieting, diarrhea, fever and seizures. Obstetrical complications including intrauterine growth retardation, placental insufficiency, fetal distress and increased risk of miscarriage and intrauterine death are also prevalent in this cohort of women. The incidence of HIV, hepatitis B and C, endocarditis and sexually transmitted diseases is higher in the drug-abusing mother. Accurate identification of in utero drug exposure has important implications for the care of the mother and the child, but also sometimes raises difficult legal issues. Society discourages prenatal care and treatment with the infliction of harsh criminal penalties for pregnant women.

Detection of in utero drug exposure has traditionally been accomplished through urine drug testing; however, the window of detection is very short, reflecting drug use for only a few days prior to delivery. Monitoring drug exposure through testing of alternative matrices, such as neonatal meconium and maternal and neonatal hair, offers several important advantages. Meconium and hair can be collected non-invasively and permit detection of drug use much earlier in gestation during critical developmental stages. In addition, maternal drug use during pregnancy can be monitored with urine, sweat, saliva and/or hair testing.

We have several important initiatives underway to address the problems of in utero drug exposure. We are monitoring pregnant heroin addicts in clinical drug treatment who are receiving methadone or buprenorphine opioid replacement medication. Treatment includes full prenatal medical care, psychological counseling, and extensive drug testing from as early as 8 weeks of gestation. For the first time, we will compare the efficacy of monitoring maternal drug exposure with thrice weekly saliva and urine, weekly sweat patch, and neonatal meconium evaluation. We will also attempt to determine if the magnitude or frequency of drug use is reflected in the concentrations of drugs and metabolites in the different specimens. We need to do more to protect drug abuse's smallest victims- our children. With the increasing numbers of drug-exposed children, we must recognize that this is an important global issue. TIAFT members around the world can make a significant contribution by developing sensitive and specific methods for the identification of in utero drug exposure and improving the interpretation of these data.

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