Date Rape Drugs
A sexual assault occurs once every 6.4 minutes in the United States, 75% of which are reported to be acquaintance rapes. The drugs gamma-hydroxybutyrate (GHB) and Rohypnol (flunitrazepam) have received an inordinate amount of coverage in the lay press and have been popularized as “date rape” drugs. The scientific literature, however, suggests that these reports are inaccurate and misleading. GHB and flunitrazepam are not as widely associated with sexual assault as popularly believed.
GHB and flunitrazepam have received particular attention in light of their rapid onset, mind-altering effects and detection difficulties. The effects of flunitrazepam, which is 7 to 10 times more potent than diazepam (Valium), begin within 15 to 30 minutes and include disinhibition, passivity, muscle relaxation and anterograde amnesia. The effects of GHB begin within 15 minutes and include disinhibition, euphoria, nausea, vomiting, respiratory depression and coma.
In a 1999 study of 1,179 alleged victims of sexual assault nationwide, the prevalence of alcohol (38%) was highest, followed by marijuana (18%), cocaine (10%), benzodiazepines (10%), amphetamines (5%), and GHB (4%). Flunitrazepam was detected in only 0.5%. A more recent study of more than 2,000 victims of sexual assault in California demonstrated that nearly two-thirds of victims tested positive for alcohol or drugs. Alcohol was detected in 63% and marijuana in 30% of cases, while GHB and flunitrazepam were detected in less than 3%.
Special precautions must be taken to detect flunitrazepam and GHB because these drugs have short half-lives and undergo rapid metabolism. The screening tests performed in most hospital laboratories are usually not sensitive enough to detect these drugs. If these drugs are suspected, the attending physician needs to inform the laboratory that the specimen should be sent to a forensic laboratory. Timely collection of specimens is also crucial in confirming the diagnosis. The victim should be urged not to urinate until the specimen can be properly collected. Collection of 100 mL of urine and 30 mL of blood, drawn into gray-top tubes, is recommended. A blood sample is especially important if the drug ingestion occurred within the past 24 hours. Positive blood toxicology can sometimes be used to corroborate involvement of the drug in the sexual assault, whereas urine toxicology only indicates prior exposure. Samples should be refrigerated immediately with the date and time of collection documented.
Rohypnol may cause a positive benzodiazepine result on some urine drug screens if it is present in high enough of a concentration. Rohypnol can be confirmed by sending the urine specimen to a reference laboratory for confirmation by GC/MS. The excretion half life is 10 to 15 hours. Rohypnol can be detected in urine up to 3 days after administration. A result of >50 ng/mL by GC/MS is considered to be a positive confirmation.
GHB should be measured in a plasma sample, rather than urine. The elimination half life is only 0.3 to 1.0 hour. Peak plasma level is reached within 20 to 60 minutes after oral administration. GHB is detectable in plasma for 6 to 8 hours after administration. A cutoff level of 5 mg/L distinguishes between endogenous and exogenous GHB. Endogenous levels are <5 mg/L. Blood levels >50 mg/L are associated with euphoria, uninhibited behavior, lightheadedness and arousal. Levels >250 mg/L are associated with seizures, coma and death.
Although drug-facilitated sexual assault is an increasing problem, GHB and flunitrazepam are not as widely associated with this crime as popularly believed. Currently, alcohol and marijuana are the most commonly encountered substances. The growing availability of some other therapeutic drugs on the illicit market such as diazepam (Valium), alprazolam (Xanax) and zolpidem (Ambien) is expected to play an increasingly important role in the near future.
