Phencyclidine: patterns seen in street drug analysis

DARK Classics in Chemical Neuroscience: Phencyclidine (PCP)

Phencyclidine (PCP, "angel dust", an arylcyclohexylamine) was the first non-natural, man-made illicit drug of abuse, and was coined 'the most dangerous drug in America" in the late 1970s (amidst sensational horror stories of the drug's effects); however, few other illicit drugs have had such a significant and broad impact on society-both good and bad. Originally developed as a new class of anesthetic, PCP-derived psychosis gave way to the PCP hypothesis of schizophrenia (later coined the NMDA receptor hypofunction hypothesis or the glutamate hypothesis of schizophrenia), which continues to drive therapeutic discovery for schizophrenia today. PCP also led to the discovery of ketamine (and a new paradigm for the treatment of major depression), as well as other illicit, designer drugs, such as methoxetamine (MXE) and a new wave of Internet commerce for illicit drugs (sold as research chemicals, or RCs). Furthermore, PCP is a significant contaminant/additive of many illegal drugs sold today, due to its ease of preparation by clandestine chemists. Here, we will review the history, importance, synthesis (both legal and clandestine), pharmacology, drug metabolism, and folklore of PCP, a true DARK classic in chemical neuroscience.

Development and validation of an LC-MS/MS method for determination of phencyclidine in human serum and its application to human drug abuse cases

A new analytical method was developed and validated for the rapid determination of phencyclidine (PCP) in human blood and serum. Rapid chromatographic separation decreased the analysis time relative to standard gas chromatography (GC)-based methodologies. The method involved the use of solid-phase extraction for sample preparation and cleanup followed by liquid chromatography tandem spectrometric (LC-MS/MS) analysis and an electrospray-ionization (ESI) interface. PCP was quantified using multiple-reaction-monitoring with deuterium labeled PCP (PCP-d(5)) as an internal standard. The method was validated for accuracy, precision, linearity, and recovery. The method was accurate with error <14% and precision with coefficient of variation (CV) <5.0%. The assay was linear over the entire range of calibration standards (r(2) > 0.997). The recovery of PCP after solid-phase extraction was greater than 90% with the lower limit of detection (LLOD) for PCP in 500 µl of human serum after solid-phase extraction at 0.06 ng ml(-1). This method was used to determine the levels of PCP in postmortem human blood samples. The LLOD in blood was 1 ng ml(-1). Blood PCP concentrations were also determined separately using GC and flame ionization detection (FID). Blood calibration standards and serum calibration standards yielded similar concentrations when used to quantitate authentic human blood samples that tested positive for PCP under the GC-FID method. Extraction of PCP from serum required fewer steps and therefore could be used as a calibration matrix in place of blood. The LC-MS/MS methodology shown here was higher throughput compared with GC-based methods because of very short chromatographic run times. This was accomplished without sacrificing analytical sensitivity.

Screening for drugs of abuse (II): Cannabinoids, lysergic acid diethylamide, buprenorphine, methadone, barbiturates, benzodiazepines and other drugs

Requirements for the provision of an efficient and reliable service for drugs of abuse screening in urine have been summarized in Part I of this review. The requirements included rapid turn-around times, good communications between requesting clinicians and the laboratory, and participation in quality assessment schemes. In addition, the need for checking/confirmation of positive results obtained for preliminary screening methods was stressed. This aspect of the service has assumed even greater importance with widespread use of dip-stick technology and the increasing number of reasons for which drug screening is performed. Many of these additional uses of drug screening have possible serious legal implications, for example, screening school pupils, professional footballers, parents involved in child custody cases, persons applying for renewal of a driving licence after disqualification for a drug-related offence, doctors seeking re-registration after removal for drug abuse, and checking for compliance with terms of probation orders; as well as pre-employment screening and work-place testing. In many cases these requests will be received from a general practitioner or drug clinic with no indication of the reason for which testing has been requested. This also raises the serious problems of a chain of custody, provision of two samples, stability of samples, and secure and lengthy storage of samples in the laboratory-samples may be requested by legal authorities several months after the initial testing. The need for confirmation of positive results is now widely accepted but it may be equally important to confirm unexpected negative results. Failure to detect the presence of maintenance drugs may lead to the patient being discharged from a drug treatment clinic and, if attendance at the clinic is one of the terms of continued employment, to dismissal. It seems likely that increasing abuse of drugs and the efforts of regulatory authorities to control this, will lead to the manufacture of more designer drugs. Production of substituted phenethylamines was facilitated by the drug makers' cook book, 'PIHKAL' (Phenethylamines I Have Known And Loved) by Dr Alexander Shulgin and Ann Shulgin, and production of substituted tryptamines is promised in their next book, TIHKAL. Looking to the future, laboratories will need to ensure that they can detect and quantitate an ever-increasing number of drugs and related substances. The question of confidence in results of drugs of abuse testing raised in 1993 by Watson has assumed even greater importance as a result of attention focused on the OJ Simpson trial in Los Angeles. Toxicological investigations are likely to be challenged more frequently in the future. Even if analyses have been performed by GC-MS, there is a need to establish the level of match between the spectrum of the unknown substance and a library spectrum which is considered acceptable for legal purposes. It will also be essential to ensure that computer libraries contain spectra for all substances likely to be encountered in drugs of abuse screening.

Different capability of N-methyl-D-aspartate antagonists to elicit EEG and behavioural phencyclidine-like effects in rats

Phencyclidine (PCP), a drug inducing schizophrenia-like symptoms in humans, is reported to be a non-competitive antagonist at the N-methyl-D-aspartate (NMDA) subtype of excitatory amino acid receptors. In rats, PCP produces three dose-dependent stages of EEG patterns: 1) increase of cortical desynchronization duration; 2) increase of the amplitude of the high-frequency (20-30 Hz) low-voltage (30-50 microV) cortical background activity; 3) appearance of cortical slow (2-3 Hz) wave-sharp wave complexes. These EEG changes are accompanied by stimulatory-depressive effects such as stereotypy (circling, head weaving) and ataxia. In the present study, the EEG and behavioural effects induced by systemic administration of the NMDA antagonists dizocilpine (MK 801), dextromethorphan (DM), [(+)-alpha-(4-chlorophenyl)-4- [(phenyl)methyl-1-piperidine ethanol] (SL 82.0715), (+)3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), cis-4-phosphonomethyl-2-piperidine-carboxylic acid (CGS 19755) have been compared to those of PCP in rats. The rank of potency for inducing PCP-like EEG stages 1-3 was as follows: MK 801 > PCP > CGS 19755 > CPP. These drugs also induced PCP-like behavioural effects. On the contrary, DM and SL 82.0715, administered up to the dose of 100 mg/kg IP, failed to induce PCP-like behavioural effects and elicited only the stage 1 of PCP-like EEG. These results strongly suggest the involvement of NMDA neurotransmission in the behavioral and EEG effects of PCP.

Patterns of lifetime drug use among intravenous drug users

To obtain a clearer description of the natural history of intravenous drug use (IVDU), 92 intravenous drug users (IVDUs), not selected through treatment or contact with the legal system, were identified. Concerning lifetime use, central nervous system (CNS) stimulants were the most common class of drug to be injected (by 72.8% of IVDUs), followed by opiates (by 50.0% of IVDUs). Mean age of onset of IVDU in this sample was 18.5 years, following initiation of alcohol use by an average of 4.6 years and cannabis use by an average of 2.1 years. Any history of IVDU in this sample indicated substantial lifetime use of illicit drugs and early onset of psychoactive substance use.

Behavioural and electoencephalographic interactions between haloperidol and PCP/sigma ligands in the rat

Phencyclidine (PCP) and sigma ligands produce a typical excitatory behaviour in rats, characterized by circling and head- and body-weaving. Excitatory amino acid antagonists such as 2-amino 5-phosphonovaleric acid (AP5) or 3-(+/-)-2-carboxypiperazin-4-yl)propyl-l-phosphonic acid (CPP) also produce a PCP-like excitatory behaviour in rats. In the present paper, the interactions between PCP/sigma drugs or excitatory amino acid receptor antagonists and haloperidol have been investigated in rats. In addition, the influence of two other butyrophenones having a different affinity for the sigma/haloperidol receptors, such as spiperone and 3-(4-(3(4-fluorobenzoyl)-propyl-piperazino-l-yl-isoquinolino (HR 375), has been tested on the behavioural and EEG effects of PCP/sigma drugs and excitatory amino acid antagonists. PCP (2.5-5 mg/kg IP), (+) or (-) SKF 10,047 (1-15 mg/kg IP), (+) or (-) cyclazocine (2-8 mg/kg IP) and AP5 (0.5 mumol ICV) dose-dependently and significantly (P less than 0.01) antagonized the haloperidol-induced catalepsy in the horizontal bar and podium tests in rats. On the other hand, either haloperidol (1 mg/kg IP) or spiperone (1 mg/kg IP) reduced the head-weaving induced by (+) SKF 10,047, PCP, or AP5. On the contrary, HR 375 (6 mg/kg IP) was ineffective in blocking the excitatory effects of these drugs. In addition, either haloperidol (1 mg/kg IP) or spiperone (1 mg/kg IP), but not HR 375 (6 mg/kg IP) reduced the amplitude increase of the fast (20-30 Hz) frequency/low (30-50 microV) voltage background cortical activity elicited by PCP or (+) SKF 10,047. The results demonstrate an interaction between dopamine and excitatory amino acid receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

"Designer drugs"--a current perspective

Since the late 1970s, in an effort to quench the ever burgeoning appetite for pharmacological substances of abuse and to satiate their own need for profit, unscrupulous chemists have set up clandestine laboratories to produce and market new drugs for street sale. Using fairly common industrial chemicals, they have altered or modified preexisting controlled substances such as fentanyl, meperidine, mescaline, amphetamine, and phencyclidine, producing derivatives of these parent compounds that, up until 1986, were able to temporarily elude the guidelines of the Federal Controlled Substances Act due to their new and unique chemical structures. Unsuspecting users continue to use the drugs recreationally. This article will present a comprehensive review of these "Designer Drugs" looking at historical data, pharmacokinetics, treatment, abuse trends, and some of the more recent additions to the social pharmacopoeia.

MMPI subtypes for chronic phencyclidine (PCP) abusers

The present study applied empirical clustering procedures to the MMPI protocols of 196 chronic phencyclidine (PCP) abusers. Subjects were randomly divided into two groups, and two methods of cluster analysis, the average linkage method and Ward's hierarchical procedure, were performed. Both cluster methods produced highly comparable results within each group, and the MMPI profiles found in each group were quite similar. Cluster analytic studies of other substance abuse populations are needed in order to replicate the MMPI profile types found in the present study. These investigations would lead to an empirical typology across various substance abuse populations that would depict developmental stages.

Misrepresentation of stimulant street drugs: a decade of experience in an analysis program

The findings of the Los Angeles County Street Drug Identification Program over the period from 1971 to 1980 for analysis of 1163 samples of street drugs represented as stimulants are presented. Of the 614 alleged cocaine samples, cocaine was found to be absent in 19.2%, found combined with stimulant substitutes in 22.5%, and found by itself in 58.3% of these samples. The validity for 473 alleged amphetamine samples was only 27.1%, with 23.0% of samples found to contain stimulant substitutes along with amphetamine, and 49.9% of the samples lacking any of the alleged drug. Seventy-six alleged methamphetamine samples showed 32.9% validity, with 3.9% of samples having mixtures of alleged drug and substitutes, and 63.2% of samples lacking any methamphetamine. A total of 15 different stimulant substitutes were found in 74 combinations. Caffeine, ephedrine, lidocaine, and procaine were the commonest substitutes.

Effects of cigarette smoke and 3-methylcholanthrene on the disposition of phencyclidine and its N-ethylamine analogue in the isolated perfused lung of rats

The isolated perfused lung (IPL) of rats were used to examine the pulmonary disposition and metabolism of radiolabeled phencyclidine (PCP) and N-ethyl-1-phenylcyclohexylamine (PCE). The IPL removed PCP and PCE from the perfusate and converted them to free and conjugated metabolites. At the conclusion of a 1-h perfusion, the lung accumulated at least 20% of the administered radioactivity and metabolized more than 30% of the added drug. Pretreatment of rats with 3-MC or cigarette smoke enhanced significantly PCP and PCE metabolism by the IPL. The concentration of conjugated PCE metabolite in the perfusate of the IPL was increased significantly by both 3-MC and cigarette smoke pretreatments whereas the concentration of conjugated PCP metabolite was not affected by cigarette smoke exposure and increased only slightly after 3-MC pretreatment. Pretreatment of rats with 3-MC or cigarette smoke also altered the amount of radioactivity accumulated by the lung tissue at the conclusion of a 1-h perfusion. Inasmuch as PCP and PCE are often abused by humans via smoke inhalation, a significant amount of these drugs may be stored or metabolized by the lung.

Effects of pentobarbital and d-amphetamine on oral phencyclidine self-administration in rhesus monkeys

Three rhesus monkeys self-administered phencyclidine (0.25 mg/ml) during daily 3-hr sessions. Water was also available under a concurrent fixed-ratio (FR) 16 schedule. In Experiment 1, saline or three doses of pentobarbital (2.5, 5 or 10 mg/kg) were injected 10 min before phencyclidine (and water) self-administration sessions. The 2.5 mg/kg pentobarbital dose increased phencyclidine-maintained responding, the 5 mg/kg dose produced mixed effects among the three monkeys, and the 10 mg/kg dose consistently decreased phencyclidine-maintained responding. Subsequently, a saccharin solution (0.03% wt/vol) replaced phencyclidine, and the pentobarbital pretreatment procedure was repeated. Pentobarbital produced dose-related decreases in saccharin-maintained responding. In Experiment 2, saline or three doses of d-amphetamine (0.05, 0.1 or 0.2 mg/kg) were injected 10 min before the phencyclidine self-administration sessions. The 0.05 mg/kg dose produced increases in phencyclidine-maintained responding, while the two higher doses produced dose dependent decreases in responding. When a saccharin solution (0.03%, wt/vol) replaced phencyclidine during the daily sessions, d-amphetamine produced only dose-related decreases in saccharin-maintained responding. These results indicate that pentobarbital and d-amphetamine have a biphasic effect on phencyclidine-maintained behavior; low doses increased responding and high doses decreased responding.

The dispositional kinetics of phencyclidine and its N-ethylamine analogue in rats

The uptake kinetics of [3H]-labelled phencyclidine (PCP) and N-ethyl-l-phenycyclohexylamine (PCE) in rats, measured in terms of decreases in the blood concentrations of the drugs after i.v. administration of a single 1.09 mumol dose, were not significantly different. Within a week of administration, the rats excreted about 93% of the [3H]-PCP and about 65% of [3H]-PCE via their urine and faeces; their urine contained nore [3H], mainly as metabolites of [3H]-PCP and of [3H]-PCE, than their faeces. Similarly, more [3H] remained in the tissues of rats treated with [3H]-PCE than in the tissues of [3H4-PCP-treated rats. The fact that PCE is metabolized and excreted more slowly than PCP may account for the higher psychotropic effects of PCE.

Phencyclidine-induced stereotyped behaviors in rats following specific neurotoxin lesions of the striatum

All the components of phencyclidine(PCP)-induced stereotyped behaviors, including sniffing, backpedalling, turning and head weaving were significantly decreased in rats following kainic acid lesion of the striatum. In the 6-hydroxydopamine lesioned rats, the behavioral score of PCP-induced stereotyped sniffing was similar to that in the sham-operated rats, while other components were significantly decreased. In addition, only the PCP-induced backpedalling and head weaving were significantly attenuated in the 5,6-dihydroxytryptamine lesioned rats. These results suggest that not only dopaminergic but also serotonergic and other systems in the striatum may play important roles in PCP-induced stereotyped behaviors.

Effect of lesions in the striatum, nucleus accumbens and medial raphe on phencyclidine-induced stereotyped behaviors and hyperactivity in rats

The effect of lesioning the striatum, nucleus accumbens and medial raphe on phencyclidine(PCP)-induced stereotyped behaviors and hyperactivity was investigated to determine the site or sites of actions of PCP in rats. Bilateral lesions of the striatum diminished or abolished all the parameters of PCP-induced stereotyped behaviors, including sniffing, back pedalling, turning and head weaving 7 days after the operation. The medial raphe lesion significantly reduced PCP-induced back pedalling and head weaving. Bilateral lesions of the ventral portion of the nucleus accumbens did not affect the PCP-induced stereotyped behaviors. On the contrary, none of the lesions altered the sensitivity to PCP-induced hyperactivity 7 days after the operation. These results suggest that PCP-induced stereotyped behaviors may be mediated in the striatum and the medial raphe but not the nucleus accumbens. Furthermore, PCP-induced hyperactivity may not result from PCP effects on these discrete brain areas.

The PCP epidemic: a critical review

The scientific literature on PCP (phencyclidine) was reviewed with a view to determining whether or not current knowledge coincides with the picture of PCP presented by the popular media. The media portray PCP as an insidious drug whose use has reached almost epidemic proportions among American youth. Serious adverse reactions, including psychosis and violent behavior, are seen as common if not inevitable consequences of use. The literature indicates that this picture of PCP is not justified. Both the prevalence of use and the relative frequency of severe adverse effects appear to have been overstated by the media.

Quantification of phencyclidine in mainstream smoke and identification of phenylcyclohex-1-ene as pyrolysis product

Parsley cigarettes containing [3H]phencyclidine were machine smoked, and the mainstream smoke was trapped in glass wool filters. Radioactivity was extracted from these filters with chloroform. The average recoveries of radioactivity were 76, 85, 70, and 69% for cigarettes containing 3, 10, 30, and 50 mg of [3H]phencyclidine hydrochloride, respectively. TLC and GLC-mass spectrometry were employed to identify and quantify compounds in the filter extracts. Approximately one-half of the recovered radioactivity represented a pyrolysis product, phenylcyclohex-1-ene. Formation of this product involved loss of piperidine from phencyclidine. Piperidine, which was not radiolabeled, also may appear in smoke intact. The remainder of the radiolabeled material represented unchanged phencyclidine. Therefore, the percentage of [3H]phencyclidine delivered was approximately 40% of the amount smoked. This result was independent of puff frequency and quantity of phencyclidine hydrochloride smoked over the range tested. The [3H]phencyclidine delivery was compared to the quantities of [3H]-delta 9-tetrahydrocannabinol and [3H]nicotine delivered in mainstream smoke. The recovery of unchanged [3H]-delta 9-tetrahydrocannabinol from placebo marijuana cigarettes injected with a solution containing 3 mg of delta 9-tetrahydrocannabinol was 60%. Tobacco cigarettes injected with [3H]nicotine yielded 70% unchanged nicotine in mainstream smoke.

Acute phencyclidine intoxication: clinical patterns, complications, and treatment

We describe four major and five minor clinical patterns of acute phencyclidine (PCP) intoxication and give the incidence of findings in each pattern. Major patterns were acute brain syndrome (248 cases; 24.8%), toxic psychosis (166 cases; 16.6%), catatonic syndrome (117 cases; 11.7%), and coma (106 cases; 10.6%). Minor patterns included lethargy or stupor (38 cases; 3.8%), and combinations of bizarre behavior, violence, agitation, and euphoria in patients who were alert and oriented (325 cases; 32.5%). Patients with major patterns of PCP toxicity usually required hospitalization and accounted for most complications. In general, patients with minor patterns had mild intoxication and did not require hospitalization except for the treatment of injuries or autonomic effects of PCP. Various types of injuries occurred in 16%, and aspiration pneumonia occurred in 1.0% of all cases. There were 22 cases of rhabdomyolysis (2.2%), with three patients requiring dialysis for renal failure. One patient who had been comatose from PCP died suddenly. A fresh pulmonary embolism was found at autopsy.

Behavioral rating scales for assessing phencyclidine-induced locomotor activity, stereotyped behavior and ataxia in rats

Behavioral rating scales were developed for quantification of phencyclidine (PCP)-induced locomotor activity, stereotyped behavior and ataxia in rats. The dose-response relationship for PCP-induced locomotor activity was found to be an inverted U-shaped function over the first 25 min after injection while over the last 30 min of the experiment the function was highly linear. A linear dose-response relationship was found for ratings of stereotyped behavior and ataxia throughout the 90 min period of observation. The ratings of these two behaviors were found to be closely parallel. The effects of PCP on locomotor activity were found to be greatest during those intervals when stereotyped behavior and ataxia were at moderate levels. Ratings of locomotor activity may be confounded by ataxia when PCP is administered alone or in combination with other drugs.

PCP (phencyclidine): an update

The steady rise in the promiscuous use of phencyclidine (PCP) as a "recreational" drug has recently gained nationwide attention because of the numerous violent and/or bizarre incidents caused by the use of this drug. Because the media often exaggerate reports of bizarre and violent behavior to make a "good" story, the potential PCP user may be tempted to ignore the media warnings. In the case of PCP, however exaggerated the story, a real danger does exist. So, despite numerous newspaper, radio and television warnings about the possible consequences of PCP use and abuse, the incidence of toxic reactions continues to climb. In many cases PCP is sold as other drugs, particularly THC, and in various colored capsules, tablets, liquids and crystals which may explain the increased usage despite the numerous warnings against its use. The advances in laboratory techniques and chemical processess have enabled the clandestine chemist to prepare relatively pure PCP and thus eliminate many of the toxic side effects due to impurities in the drug. In addition, 30 or more psychoactive PCP analogues have been developed and are starting to make an appearance on the street. PCP is perhaps the most potent psychotomimetic compound known at the present time and is capable of inducing a psychosis which is clinically indistinguishable from schizophrenia. The psychosis-producing effects of PCP are the most common toxic effects seen in hospital emergency rooms; but as the amount of PCP taken and/or the simultaneous involvement of other drugs, particularly barbiturates, occurs, severe medical problems (e.g., coma, seizures, respiratory arrest) begin to appear. Death from high doses of PCP or PCP plus other drugs does occur, but the principal cause of death from PCP abuse is due to trauma, homicide or suicide (usually of the bizarre or violent form). Young adult males, persons predisposed to mental illness and naive drug users appear to be the most susceptible to the adverse effects of PCP. The fact that chronic PCP users are starting to increase in number is mute testimony that not all users experience "bad trips" with PCP. Unfortunately for the user, however, this does not guarantee that the next trip will not be a bad one. The effects of chronic use seem to be twofold: severe depression with suicidal thoughts and numerous violent, agitated behavioral patterns. Neither seems to be a suitable alternative. At the present time there is not specific antidote for toxic PCP reactions and the prolonged psychosis induced in some cases does not appear to respond to the standard antipsychotic medications as quickly as do the functional psychoses. The major improvement from a medical standpoint is the development of more sensitive laboratory techniques to confirm the presence of PCP in body fluids. This advance has undoubtedly led to the apparent increase in the number of PCP cases reported by hospitals and to the accuracy of clinical diagnosis by medical, drug or law enforcement communities...

Emergency management of acute phencyclidine intoxication

Phencyclidine (PCP) is a potent sympathomimetic and hallucinogenic dissociative anesthetic agent. As an abused street drug, it is most often smoked, thus allowing the user to titrate the dose. The clinical signs of PCP intoxication can be viewed in three dose-related stages, but waxing and waning of signs through the three stages is not uncommon. Treatment protocols for each stage address drug therapy and both clinical and psychological supportive measures.

Angel dust use in an outpatient setting--clinical profile and implications for treatment

The study attempts to identify two populations of 20 young people who are self-reporting marijuana use in one group and angel dust in the other. We have examined these populations and evaluated them on a series of variables in an attempt to discover whether there are significant differences between them and, if so, whether there is in fact a clinical profile which may be descriptive of nonacute reactions to angel dust. Results indicate that there are significant differences on variables that distinguish angel dust users in an outpatient setting.

Phencyclidine deaths

The potential for a pharmacologic "overdose" and the cause of death associated with phencyclidine abuse is discussed. Nineteen deaths associated exclusively with phencyclidine intoxication have been documented. In 13 cases the immediate cause of death was asphyxia by drowning or trauma with lower levels of phencyclidine present suggesting behavioral toxicity. In two cases, the presence of phencyclidine in high concentrations constituted the only finding, and the probable cause of death was primary respiratory depression accompanied by seizure activity. A secondary drug effect or concurrent disease process may have contributed to the death of the remaining four individuals.