The current urine drug of abuse panels ("Drug of abuse – urine" [LAB500]; "Drug of abuse-urine + confirm" [LAB1032]) contain screening tests for amphetamines, barbiturates, benzodiazepines, cocaine, opiates, and oxycodone/oxymorphone. An analysis of drug of abuse test results over the last 7 years has revealed a declining rate of positives for the barbiturates assay, with only 1.1% of drug of abuse panels ordered in 2010 at University of Iowa Hospitals and Clinics testing positive for barbiturates (compared with 3.0% for amphetamines, 18.2% for benzodiazepines, 6.1% for cocaine, 18.0% for opiates, and 3.8% for oxycodone).

Of the barbiturate positive screens that we have confirmed by send-out testing in the last 7 years, 13% are due to butalbital (weak-acting barbiturate in Fiorinol), 9.2% to pentobarbital (entirely resulting from use of this drug in hospital procedures to patients or to pregnant mothers of infants who are tested after birth), 51% to phenobarbital, and 26% false positives. There is little difference between neonates and adult patients in the rate of positivity, mostly because the barbiturates that cause positives (butalbital, phenobarbital, and pentobarbital) are used by or given to pregnant mothers as well as other adults. In 7 years, we have not detected any confirmed case of the short-acting barbiturates such as secobarbital or amobarbital that were significant drugs of abuse in the 1960s and 1970s. The trends at Iowa reflect nationwide patterns of drug use. Overall, barbiturates have faded as drugs of abuse, given the replacement of barbiturates as sleeping pills with benzodiazepines and non-benzodiazepines such as zolpidem (Ambien) or eszopiclone (Lunesta).

Effective August 30, 2010, we are thus removing the barbiturates screen from the two urine drug of abuse panels. This leaves a 5 drug panel (amphetamines, benzodiazepines, cocaine, opiates, and oxycodone/
oxymorphone).

If urine screening for barbiturates is desired, this can still be ordered in Epic as "Barbiturates-urine screen" [LAB7383].

Questions should be directed to Matthew Krasowski, MD, PhD, medical director of the Clinical Chemistry (384-9380, matthew-krasowski@uiowa.edu).