The cases of alleged drug-facilitated sexual assault are increasing worldwide and have caused alarm in the general population. Sexual assault on both women and men has been the focal event of many investigations conducted by law enforcement agencies.1
The administration of various sedative drugs to modify a person's behavior and to cause amnesia for criminal purposes is not a new phenomenon. However, the fact that these drug-facilitated crimes have been increased during recent years, has not only sensitized law enforcement agencies and doctors, but also has kept them alert.2 The drugs most often used in drug-facilitated crimes, such as sexual assault and robbery, are medicaments such as benzodiazepines (flunitrazepam, lorazepam, diazepam, temazepam, clonazepam, oxazepam), hypnotics (zopiclone, zolpidem), sedatives (neuroleptics, some histamine H1- antagonists), anesthetics (γ-hydroxybutyrate, ketamine), scopolamine, drugs of abuse, such as cannabis, ecstasy, lysergide or ethanol, or a combination of the referred drugs with ethanol.3–5 These substances are generally short acting and they can impair an individual rapidly. According to the statistics available for drugs involved in drug-facilitated sexual assaults in the Institute of Legal Medicine in Strasbourg, zolpidem ranks first among these drugs.3
Zolpidem is a sedative-hypnotic drug used in Europe for the treatment of insomnia since 1986 and since 1993 in the United States.6 It is an imidazopyridine derivative, with a chemical structure unrelated to benzodiazepines.2,7 The drug is available in 5 to 10 mg tablets as the tartrate salt for oral administration, intended for once-nightly consumption at a dose of 10 mg. Despite its sedative action related to omega-1 receptors, its severe side effects include impairment of psychomotor performance and disturbances of recent or remote recall.4,8 These effects can increase the victim's susceptibility to sexual assault and may provoke a considerable delay before the victim is able to report the allegation to police or to a doctor or until the victim's memory returns.
A 35-year-old woman complained to her doctor for dizziness, loss of memory, and vaginal irritation for a period of 10 days. She was admitted to the hospital and she mentioned to the doctors that she was recently suffering from a gastric ulcer and she was under therapy with Losec (omeprazole), in the form of capsules, 20 mg/d for the last 4 to 8 weeks (Fig. 1). She also mentioned that the capsules were given to her by her husband. Finally, she declared suspicions for sexual assault by her husband, mentioning that, due to her religious beliefs, she was refusing to have a sexual intercourse with him for the entire fasting period of 40 days before Orthodox Easter.
The woman was sent to the Department of Forensic Medicine and Toxicology for both clinical and toxicological examination. Her physical examination did not reveal any marks of violence and a toxicological analysis of her biologic fluids was performed.
MATERIALS AND METHODS
Blood and urine were sampled at the admittance and were stored at 4°C until analysis. The urine sample was screened for amphetamines, barbiturates, benzodiazepines, cocaine metabolite (benzoylecgonine), cannabinoids, methadone and opiates by fluorescence polarization immunoassay TDx (Abbott), by enzyme immunoassay VIVA (Dade Behring) and by Triage (Merck). Blood was analyzed for alcohol by GC-head space method. Blood and urine samples were analyzed for basic drugs, after Chem-Elut extraction, by GC/MS.
One milliliter of urine and 1 mL of blood each diluted with 4 mL of phosphate buffer (K2HPO4) pH 9 were extracted using Chem-Elut extraction columns (Varian), as described by Lillsunde and Korte, (1991).9
After the extraction, each eluent was evaporated to dryness under a stream of N2, and was analyzed each by GC-MS was reconstituted with 50 μL of ethyl acetate. Mass spectra were obtained by a Shimadzu QP 5000 GC-MS under the following conditions:
- HP-5 MS capillary column with cross-bond 5% (Phenyl)-methyl polysiloxane (30 m in length, 0.25 mm i.d., 0.25 μm film thickness).
- Initial column temperature: 100°C; Initial time: 1 minute.
- Final column temperature: 295°C; Rate: 15°C/min; Final time: 10 minutes.
- Injection port temperature: 280°C Splitless injection.
- Interface temperature: 300°C.
- Carrier gas: Helium; Flow rate: 1 mL/min.
- The retention time of zolpidem was 15.7 minutes.
- After the detection of zolpidem in the urine of the victim, quantitation of the drug in blood was performed.
RESULTS AND DISCUSSION
Negative results were obtained concerning alcohol levels and the presence of drugs of abuse in urine. Further qualitative analysis of blood and urine for basic drugs revealed the presence of zolpidem and the absence of omeprazole in both biologic samples. The concentration of zolpidem in the blood of the victim, 11 hours after the last supposedly capsule intake, was 47 μg/L.
The fact that zolpidem found during the analysis was never therapeutically taken by the woman and the absence of omeprazole in the victim's biologic fluids, which in contrast was taken therapeutically by the woman, led to suspicions for some kind of medicinal replacement. The woman insisted that she was taking only Losec capsules, given to her by her husband. Suspicions then were raised against her husband, who was probably replacing the contents of Losec (omeprazole) capsules with Stilnox (zolpidem) tablets. We asked the woman to bring the Losec capsules to our department. The capsules were opened in the laboratory and it was noticed that the entire content of each Losec capsule was replaced by one and a half of tablets of Stilnox 10 mg. The content of Stilnox tablets was later identified as zolpidem (Fig. 2). During the investigation of the case by hospital personnel, the husband confessed that, in fact, he had tampered the capsules this way to have sex with his wife, since she was not willing to participate voluntarily due to her religious restraints.
According to pharmacological data, zolpidem is characterized by the fast onset of its sedative action and its relatively short elimination half life which ranges between 1.4 and 4.5 hours.10,11 Due to these properties, it can impair an individual rapidly and due to its amnesic properties, the victim can not accurately recall the circumstances of events that take place while he/she is under influence.
The presentation of this rare and unusual case illustrates that law enforcement agencies and investigative authorities must never forget that sexual assaults can also be drug facilitated and they should pay the appropriate attention during their investigation. Furthermore, the medical staff involved in such cases should also keep in mind that a thorough toxicological examination can sometimes clarify the circumstances under which a specific act took place and give substantial evidence for the prosecution of the perpetrators.
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