1. Introduction Results: Pharmacokinetic Analysis Results: Behavioral Analysis Conclusions Methods The dissociative anesthetic ketamine, a derivative of phencyclidine (PCP), is appearing as a "club drug" at rave parties and at bars. It is taken voluntarily or involuntarily when it is unknowingly added to a drink for drug-facilitated sexual assault 1,2 (i.e., a “date-rape” drug). Ketamine functions as a date-rape drug by producing sedation, stupor, and memory impairment rendering the victim defenseless and helpless in recalling details of the incident. When abused, ketamine can produce psychotic symptoms and cognitive impairment that persist up to 3 days 3,4. When used as an anesthetic, patients frequently report adverse events during recovery including vivid and unpleasant dreams or hallucinations, amnesia, inability to concentrate, and altered cognition. A common use of ketamine is to sedate and immobilize large animals in zoos and research facilities 1. However, the possible contamination of the results due to residual effects of ketamine has, to our knowledge, not been considered. Ketamine is rapidly metabolized with the principal metabolites being an active metabolite, norketamine, and an inactive metabolite, 6-hydroxynorketamine 5 (Fig. 1). Ketamine is N-demethylated to norketamine by the cytochrome P450 system, predominantly CYP3A4 6. Norketamine has equal to less active NMDA antagonist properties than ketamine 7. In this study, we report preliminary results that norketamine persists in monkey blood and urine for days after a single-dose administration of ketamine and that some behavioral changes are seen more than one week later.  In monkeys, norketamine serves as a qualitative marker of ketamine exposure for more than 30 days in urine and for at least 12 days in plasma. Norketamine may be an important clinical marker for ketamine intoxication, particularly in drug-facilitated sexual assault cases.  This pilot study provides evidence that behavioral changes persist for up to 12 days after single dose administration of a low anesthetic dose of ketamine to monkeys.  Although plasma and urinary levels of norketamine were low after the first day, the presence of this active metabolite of ketamine plus evidence of behavioral changes for several days after acute administration of ketamine suggest that these findings warrant further investigation.  Also, the results bring into question the indiscriminate use of ketamine in veterinary medicine as a large animal immobilizer. The subjects for the study were a stable social colony of five adult stumptail macaques (Macaca arctoides), four females and one dominant male. None of the animals had received ketamine for at least 6 months prior to the study. Expt. 1: Ketamine and Norketamine levels in monkey urine. Each monkey was individually caged for collection of urine. One sample was collected prior to drug administration. All monkeys received a single IM injection of ketamine, 5 mg/kg, on a Monday. Urine was collected 18 hr/day on weekdays through Day 24, then once every four days through Day 35. The levels of ketamine and norketamine in urine were measured using solid-phase extraction followed by the negative ion chemical ionization gas chromatography- mass spectometry quantitation of both compounds. Expt. 2: Behavioral analysis and Ketamine and Norketamine levels in monkey plasma. Following a 6 month drug washout, Expt. 2 started. The monkeys were continuously housed as a colony of five animals. The 4 females received treatment in a crossover design. Each phase began with a 5 day baseline (B) observation period followed by a single IM injection of ketamine, 5 mg/kg. Observation was conducted by a trained, blind observer 4 hr after injection and on Days 2-5 and Days 8-12 in addition to baseline. The observer recorded the behavior of each monkey for 1 hr using the focal sampling technique for 44 social, solitary, and drug- induced behaviors 8. Seven weeks separated the ketamine injections for each pair of subjects. The male was not treated. 2-3 cc of blood was collected by venopuncture from each of the 4 treated monkeys, 3 days before treatment (blank = B), 40 min, 2 hr and 6 hr (Day 1), 25 hr (Day 2), and Days 3, 5, 9, and 12 (following behavioral observation). Blood was spun in a centrifuge at 3000 rpm x 10 min. The plasma was removed. Ketamine and norketamine levels were measured as described above in Expt. 1. Protein precipitation was performed prior to the solid phase extraction. DETECTION OF A LONG-LASTING ACTIVE METABOLITE IN URINE AND BLOOD OF MONKEYS AFTER A SINGLE DOSE OF KETAMINE: PHARMACOKINETIC AND BEHAVIORAL ANALYSIS RF Schlemmer 1, P Adamowicz 1, BK Saini 1, MP Juhascik 1, DE Webster 2, GA Matwyshyn 1, BM Roberts 3, JM Davis 4, A Negrusz 1 1. Dept. of Biopharmaceutical Sciences and 2. Dept. of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, 3. Dept. of Physiology and Biophysics and 4. Dept. of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago IL 60612 579.16 Conc. [ng/ml] Conc. [pg/ml] Evidence of Residual Effects of Acute Ketamine on Monkey Behavior Elimination of Ketamine in Urine after Single Dose Sec. Distance from Cagemates Total Resting Time Locomotion Distance > 3 ft. Elimination of Norketamine in Urine after Single Ketamine Dose Elimination of Ketamine and Norketamine in Plasma Initiated Social Groom Ketamine Norketamine Days Behavioral changes in monkeys similar to Day 1 were present more than one week after single dose administration of ketamine for several behaviors (e.g.,social groom, distancing, resting time), but not others such as locomotion. In plasma, ketamine was not detectable after the first day after acute administration. However, norketamine was detectable throughout the 12 days of the experiment. Norketamine was present in urine for 35 days in four monkeys and for 31 days in one monkey. In urine, ketamine was detectable for only 2-4 days after acute administration in four monkeys and for 10 days in one monkey. References 1. Smith KM, Larive LL, Romanelli F (2002): Amer J Health-Syst Pharm 50:1067-1076. 2. Negrusz A, Gaensslen RE (2003): Anal Bioanal Chem 376:1192-1197. 3. Curran HV, Morgan C (2000): Addiction 95:575-590. 4. Vollenweider FX, Geyer MA (2001): Brain Res Bull 56:495-507. 5. Grant IS, Nimmo WS, Clements JA (1981): Br J Anaesth 53:805-810. 6. Shimoyama M, Shimoyama N, Gorman AL, Elliot KJ, Inturrisi CE: (1999) Pain 81:85-93. 7. Smith DJ, Bouchal RL, deSanctis CA (1982): Neuropharmacol 26 :1253-1260. 8. Schlemmer RF, Davis JM (1983): In, Miczek KA (ed) Ethopharmacology: Primate Models of Neuropsychiatric Disorders. Alan Liss: New York, pp. 33-78. University of Illinois at Chicago College of Pharmacy UIC