Phencyclidine: A 5-Year Retrospective Review from the New York City Medical Examiner’s Office

Phencyclidine Positivity on Urine Drug Screening in Patients Treated for Alcohol Withdrawal on a Dual-diagnosis Medically Assisted Withdrawal Unit

OBJECTIVES

Little contemporary research has explored phencyclidine (PCP) use in people with alcohol use disorder. Therefore, we sought to determine the prevalence of PCP positivity on urine toxicology screening among patients admitted for alcohol withdrawal, identify correlates of PCP positivity, and investigate PCP positivity's relationship to length of stay (LOS) and risk of facility readmission.

METHODS

This was a retrospective study of patients admitted to a dual-diagnosis medically assisted withdrawal unit for alcohol withdrawal from 2014 to 2019. Univariate tests and logistic regression were used to investigate potential correlates of PCP positivity on admission toxicology screening (primary outcome). Multivariable linear regression models and survival analyses analyzing LOS and risk of readmission (secondary outcomes) were also developed.

RESULTS

Ninety of 3731 patients (2.4%) screened positive for PCP. There were significant associations on univariate testing between PCP positivity and age, race, homeless status, and urine toxicology positivity for amphetamines, benzodiazepines, barbiturates, cocaine, tetrahydrocannabinol, and oxycodone. On multivariate logistic regression, only tetrahydrocannabinol, barbiturates, and cocaine positivity were associated with PCP positivity. Multivariate logistic regression and survival analysis found no statistically significant associations between PCP positivity and LOS or risk of readmission.

CONCLUSIONS

This study provides rare analysis of contemporary data on PCP use among patients undergoing medically assisted alcohol withdrawal. Phencyclidine positivity was uncommon, but use appears considerably higher among this patient population than the general population. There was no significant association between PCP positivity and LOS or readmission risk.

Phencyclidine in Drivers and Decedents in Dallas County: A 5-Year Retrospective Review of Toxicological and Demographical Data

Presented are phencyclidine (PCP)-positive cases received by the Toxicology Laboratory at the Southwestern Institute of Forensic Sciences (SWIFS) from local law enforcement agencies and the Office of the Medical Examiner (ME) between January 1, 2015, and December 31, 2020. Of the 43,940 requests for testing received during that time, 898 (2.04%) were positive for PCP. These cases were evaluated for PCP concentration, additional/concurrently reported drug concentrations, and demographics. For ME cases, cause and manner of death were also evaluated. Though the number of requests received by the Laboratory increased each year, the percentage positive for PCP remained consistent. Subjects ranged from 18 to 71 years old (median 48) and were predominantly black (94.19%) and male (78.49%). Overall PCP concentrations ranged from 0.02 to 2.33 mg/L (median 0.05 mg/L), driving while intoxicated (DWI) cases ranged from 0.02 to 0.14 mg/L (median 0.04 mg/L), and ME cases ranged from 0.02 to 2.33 mg/L (median 0.13 mg/L). In addition to PCP, one or more drug(s) or metabolite(s) was identified concurrently in 69.49% of cases. Cannabinoids were the most frequently detected (39.8%), followed by cocaine and its metabolites (22.0%), and ethanol (18.5%). Results were similar when comparing the additional drugs reported in ME and DWI cases. PCP concentrations in ME samples were generally higher, especially for stimulant drugs. Of the 264 ME cases positive for PCP, the manner of death was determined to be an accident for the majority of cases (62.54%), and the most common cause of death was drug toxicity (35.61%). The results from this study facilitate comparison of laboratory- or region-specific data sets, help determine whether laboratory scopes meet testing needs, contribute to reference ranges, and provide the foundation for well-informed policy decisions.

Toxicological and Demographic Profiles of Phencyclidine-Impaired Driving Cases in Houston

Phencyclidine (PCP) was first synthesized in 1926 and originally developed in 1950s as a general anesthetic agent. Abuse of PCP declined at the national level since its first illicit use in 1960s, but it continues in certain areas including Houston. This research evaluates PCP-positive cases of driving while intoxicated (DWI) in 2013–2018. The blood samples were collected from drivers, submitted by the Houston Police Department and analyzed for alcohol and drugs. Toxicological findings and demographic information were evaluated for the impaired driving cases tested positive for PCP in blood. Additionally, the Drug Recognition Expert (DRE) findings were examined for 12 cases in 2018. A total of 615 DWI cases positive for PCP in blood were identified in which the traffic offense occurred between August 2013 and December 2018. The mean (median, range) PCP concentration was 47 (43, 7–180) ng/mL. A total of 23% of those cases were females, and 77% were males; 85% were blacks, 10% were whites and 5% were other races/ethnicities as identified by the arresting officer. The mean age was 37 years. No significant differences in median and distribution of PCP concentrations (P’s > 0.05) were observed across the offense years and among demographic cohorts. A total of 43% of the cases were positive for PCP only. Among the remaining 57%, cannabinoids are the most common concurrently detected analytes (35%), followed by cocaine/metabolite (14%) and ethanol (13%). The proportion of black male PCP-positive drivers decreased in younger age groups. Common indications observed by DRE officers included slurred speech, chemical breath odor, watery and/or bloodshot eyes, vertical/horizontal gaze nystagmus and impaired coordination/balance. This study provides valuable regional information to better understand the demographic patterns of PCP-impaired drivers in Houston, TX over 6 years. The findings may aid in designing and implementing regulations and prevention programs to reduce PCP-impaired driving.

Altered mental status and end organ damage associated with the use of gacyclidine: a case series

INTRODUCTION

Over the past decade, there has been a sharp increase in the number of newly identified synthetic drugs. These new drugs are often derivatives of previously abused substances but have unpredictable toxicity. One of these drugs is gacyclidine, a derivative of phencyclidine (PCP). Gacyclidine has been studied as a neuroprotective agent in trauma and as a therapy of soman toxicity. There are no previous reports of its use as a drug of abuse.

CASE REPORTS

During a two-month period in the summer of 2013, a series of patients with severe agitation and end-organ injury were identified in an urban academic Emergency Department (ED). A urine drug of abuse screen was performed on all patients, and serum samples were sent for comprehensive toxicology analysis. A total of five patients were identified as having agitation, rhabdomyolysis, and elevated troponin (Table 1). Three of the five patients reported use of methamphetamine, and all five patients had urine drug screens positive for amphetamine. Comprehensive serum analysis identified methamphetamine in three cases, cocaine metabolites in one case, and a potential untargeted match for gacyclidine in all five cases. No other drugs of abuse were identified.

DISCUSSION

This is the first series of cases describing possible gacyclidine intoxication. The possible source of the gacyclidine is unknown but it may have been an adulterant in methamphetamine as all patients who were questioned reported methamphetamine use. These cases highlight the importance of screening for new drugs of abuse when patients present with atypical or severe symptoms. Gacyclidine has the potential to become a drug of abuse both by itself and in conjunction with other agents and toxicity from gacyclidine can be severe. It is the role of the medical toxicology field to identify new agents such as gacyclidine early and to attempt to educate the community on the dangers of these new drugs of abuse.

Chronic phencyclidine treatment induces long-lasting glutamatergic activation of VTA dopamine neurons

Use of phencyclidine (PCP) can mimic some aspects of schizophrenia. However, the underlying mechanism is unclear. Administration of PCP is known to activate mesolimbic dopamine pathway. In this study, we focused on ventral tegmental area (VTA) of mesolimbic dopamine pathway as target of PCP for inducing schizophrenia-like symptoms. Single VTA neuron was isolated and its neural activity was monitored by measuring cytosolic Ca(2+) concentration ([Ca(2+)]i) followed by immunocytochemical identification of dopamine neurons. Administration of glutamate increased [Ca(2+)]i in dopamine neurons from control rats, and the [Ca(2+)]i increase was inhibited in the presence of PCP. In contrast, in VTA dopamine neurons from rats chronically treated with PCP for 7 days, administration of glutamate was able to induce [Ca(2+)]i increase in the presence of PCP. Furthermore, this glutamate-induced [Ca(2+)]i increase in the presence of PCP continued even after washout of glutamate and this effect lasted as long as PCP was present. This long-lasting glutamate-induced [Ca(2+)]i increase in the presence of PCP was not observed or significantly attenuated under Ca(2+) free condition and by N-type Ca(2+) channel blocker ω-conotoxin. The results indicate that chronic treatment with PCP reverses the acute PCP effect on VTA dopamine neurons from inhibitory to stimulatory tone, and consequently induces long-lasting activation of dopamine neurons by glutamate.