False-positive urine phencyclidine immunoassay screen result caused by interference by tramadol and its metabolites.

Phencyclidine is one of the drugs of abuse included in qualitative urine drug screens that are frequently ordered in the emergency department despite concerns about specificity and clinical utility. Many drugs have been described to cause false-positive results for phencyclidine. We present 2 cases of false-positive phencyclidine qualitative urine drug screen results in patients with seizures from tramadol misuse or abuse. The involvement of tramadol and its active metabolite, N-desmethyltramadol, was confirmed by in vitro testing. These cases illustrate that tramadol and its metabolites can trigger a false-positive phencyclidine urine drug screen result in nonfatal cases and highlight the lack of specificity of the phencyclidine qualitative urine drug screen.

Chloroquine psychosis masquerading as PCP: a case report.

Chloroquine and its derivatives have been drugs of choice in the prophylaxis and treatment of malaria for over 50 years. These drugs are also frequently used in the treatment of various rheumatologic disorders. Because many Americans now travel abroad and may require chloroquine prophylaxis, as well as the fact that such medications are readily available through Internet-based supply houses, clinicians should be aware of the potential toxicity associated with the use of these agents. We present the case of an adolescent female who presented with acute, chloroquine-induced toxic psychosis resembling that induced by phencyclidine (PCP) in clinical presentation and laboratory findings. In the acute setting, the differentiation between chloroquine toxic psychosis and PCP psychosis may be difficult. Therefore, the syndrome of chloroquine-induced psychosis is reviewed and its differentiation from PCP psychosis highlighted as it relates to important aspects of this case.

Outpatient treatment of PCP abusers.

Despite the persistence of phencyclidine (PCP) abuse as a public health problem in many urban areas of the United States, there are no published data on outpatient treatment outcome. We studied 37 unselected male PCP abusers (mean age 32 years, 73% Black, 19% married, 68% unemployed) who attended at least one outpatient treatment session at the Brentwood Division, West Los Angeles VA Medical Center. Subjects had smoked PCP for an average of 7 years, with 84% using it at least weekly (38% daily) and 76% using other drugs (alcohol, marijuana, or cocaine). All subjects reported psychological dependence on PCP (i.e., liking PCP use and difficulty stopping despite adverse consequences), while none reported a physiological withdrawal syndrome when stopping PCP use. Subjects stayed in treatment an average of 21 weeks (range 1-155 weeks), attending an average of 68% of the group meetings. PCP was detected in weekly urine samples 78% of the time, with verbal self-report of recent PCP use occurring before 29% of the group meetings. Four subjects (11%) achieved at least 1 year of abstinence, 10 (30%) transferred to residential treatment or a community recovery home, 16 (48%) dropped out of treatment, and two (6%) were jailed. Treatment outcome was not significantly associated with subject characteristics. Age was the only subject characteristic that significantly predicted length of stay (r = .40).

PCP abuse in New Orleans: a six-year study.

Methods for determination of PCP in body fluids are presented and a rapid screening method is suggested. The demographics, psychiatric profiles, forensic aspects, and diagnostic problems of PCP abuse are discussed.

Extended EMIT-DAU phencyclidine screen.

In a public hospital emergency room, 580 urines were screened for phencyclidine (PCP) with the routine EMIT-DAU PCP screen, the extended EMIT-DAU PCP screen, and a gas chromatograph/mass spectrometer/computer (GC/MS/COMP) in selected ion mode, which was chosen as the reference method. The extended method produced a 38.5% increase in positives detected over the routine EMIT-DAU PCP screen and allowed 66.4% of the specimens to be signed out as negative without confirmation by GC/MS/COMP. This ability to provide a rapid, relatively inexpensive screen for PCP in urine and, in particular, to eliminate those patients whose specimens are negative, is important in a psychiatric population that contains many acutely psychotic individuals with grossly abnormal behavior.

Critical interpretation of urinary phencyclidine monitoring.

A critical appraisal of issues and problems in monitoring urinary phencyclidine (PCP) is presented. Problems may be related to impurities of ingested material and/or metabolites, and methods that are not sensitive enough to detect PCP in the nanogram/ml amounts which may be present in blood or urine. Possible false positives found with some methods are discussed. Most complicated of all is the unpredictable excretion of PCP which can result in negative urines followed by urines which test positive for PCP without necessity of any further ingestion of PCP. A set of guidelines for use in monitoring and interpreting PCP values is included.

Chronic phencyclidine abuse and physical assault.

When the authors investigated aggressive behavior on a phencyclidine (PCP) detoxification and rehabilitation unit and compared similar types of behavior on a heroin unit, they found no differences between the two units. The urinary PCP levels of a subgroup of 75 patients admitted to the PCP unit who had PCP-positive urine were significantly higher than those of 75 patients admitted to an acute psychiatric ward because of violent behavior who also had PCP-positive urine. The authors discuss the implications of these findings and the need for more information on the relationship between PCP levels in blood and urine and behavior.

Urinary phencyclidine excretion in chronic abusers.

Data on usage patterns of 100 hospitalized chronic phencyclidine abusers was collected. Weekly urine samples were monitored using a new gas chromatographic nitrogen detector analysis for PCP. Abusers were found to be, on the average, young males who had used PCP for approximately 40 months (range 12 to 96 months) and approximately 3 to 4 d/week. Except for one subject, urines became negative for PCP within 30 d after last use with a mean of 14 d. There was rapid excretion during the first 9 d followed by a more gradual reduction in urine PCP levels.

Phencyclidine intoxication: clinical experience in 27 cases confirmed by urine assay.

Medical records of 107 consecutive patients with a diagnosis of phencyclidine (PCP) intoxication were reviewed and in 27 of these the diagnosis was confirmed by positive urine assay. In the 27 confirmed cases, the most common abnormalities present on physical examination were mental/behavioral (89%) and nystagmus (85%). Elevations in blood pressure, temperature, and heart rate that were statistically significant when compared with an age-matched control group also were noted. Review of available medical records disclosed that 13 of these patients had been evaluated previously at our institution for PCP intoxication. Toxicological screening tests including blood alcohol level, hypnotic screen, and urine test for alkaloids, were performed on 11 patients and found positive in four. The most common serious medical complication requiring hospitalization was rhabdomyolysis which occurred on three patients, two of whom developed acute renal failure. This complication may occur more frequently than previously recognized and should be excluded in patients with PCP intoxication.