Confirmation of LSD intoxication by analysis of serum and urine.

Serum and urine specimens of 31 patients with suspected lysergic acid diethylamide (LSD) intoxication were analyzed for LSD by both radioimmunoassay (RIA) and high-pressure liquid chromatography (HPLC). The RIA assay, using 0.1 ng/mL as the limit of detection instead of the manufacturer's recommendation of 0.5 ng/mL, was positive for LSD in 13 blood and urine specimens from 14 patients. Results were compared to HPLC analysis using methysergide instead of lysergol as the internal standard and a limit of detection of 0.5 ng/mL. HPLC detected LSD in 9 of 13 serum specimens and 11 of 13 urine specimens that had tested positive by RIA. Of 18 patients with a final clinical diagnosis of LSD intoxication, LSD was detected by RIA in 14 patients and by HPLC in 11 patients. For 13 other cases in which the final diagnosis was a condition other than LSD intoxication, serum and urine assays for LSD were negative in all cases by both techniques. LSD assays have not been generally available in clinical laboratories. We conclude that the qualitative determination of LSD in either serum or urine by a commercially available radioimmunoassay has made it possible to provide reliable laboratory confirmation of LSD intoxication.

Estimation of theophylline clearance during intravenous aminophylline infusions.

The utility of predicting theophylline clearance (CL) from two serum concentrations obtained during continuous intravenous aminophylline infusion was examined in 16 stable, adult patients. Blood for theophylline measurement was obtained 0, 6, and 12 h after starting infusions and, thereafter, at 12-h intervals. EMIT was used to assay samples in multiple runs as they were obtained. Later, each sample was reassayed by EMIT within a single run. Bayesian least-squares regression and the algebraic method of Chiou were used to predict CL using the 0,6 and 0,12 h concentrations. "Actual" CL was measured by nonlinear least-squares regression of all concentrations obtained during prolonged infusions. Prediction bias and precision were assessed by calculating mean percent error (PCE) and mean absolute percent error (APCE), respectively. A three-way repeated-measures ANOVA was used to examine the effect of the method of CL prediction, assay procedure, and time interval between samples on PCE and APCE. Bayesian predictions were less biased and slightly more precise than Chiou predictions. The assay procedure had no effect on bias but precision was improved using a single-assay run. Predictions were less biased and more precise with 0,12 h versus 0,6 h data. Serum samples for theophylline measurement should be obtained after initiating constant intravenous aminophylline and again 8-12 h later in stable, adult patients. Prediction of CL with either of the concentration-based methods studied will then allow safe and rapid adjustment of dosage to achieve therapeutic serum concentrations.

Detection of phencyclidine usage by radioimmunoassay of saliva.

Paired serum and saliva samples, obtained from 100 emergency department patients suspected of phencyclidine (PCP) intoxication, were analyzed using a specific PCP radioimmunoassay (RIA). Seventy-four of the 100 saliva samples and 75 of the paired serum samples were positive for PCP. The final clinical diagnosis was PCP intoxication in 79 cases. Of these, both serum and saliva tests were positive in 70 cases, only serum was positive in two cases, and both serum and saliva samples were negative in seven cases. The concentration of PCP in the samples did not correlate with the severity of PCP intoxication. In the remaining 21 cases, with no clinical evidence of PCP intoxication, PCP assays were negative in both serum and saliva in 17 cases, three patients had positive saliva and serum tests, and one other patient had a positive PCP saliva assay. Thus, saliva would appear to be as reliable as serum as a specimen for PCP analysis.

Quantitation of phencyclidine in serum by enzyme immunoassay: results in 405 patients.

Phencyclidine (PCP) in serum (5 ng/mL and higher) was quantitated by a homogeneous enzyme immunoassay procedure. Precision and accuracy data indicate that the procedure meets the requirements for a clinical assay. The short turnaround time for the assay makes it superior to other available methods for the emergency determination of PCP in serum. The analytical results were comparable to those by GC/MS on 70 samples tested. The serum concentration of PCP was determined in 500 specimens from 405 patients. In 216 patients with "pure" PCP intoxication, the serum concentration did not show a direct relationship to either the clinical pattern of intoxication or to the history of the route of PCP use.

Quantitation of phencyclidine in urine by enzyme immunoassay.

The EMIT phencyclidine assay was modified to permit quantitative results to be obtained on urine from patients intoxicated from ingestion of phencyclidine (PCP). Additional calibrators and a clinical processor for calculating the data are required. Precision and accuracy of the quantitative procedure was determined from urine spiked with PCP. The accuracy and specificity were determined by comparing the results obtained by the EMIT procedure with results obtained by gas chromatography. The procedure meets the requirements for a quantitative clinical assay. The short turnaround time of the assay makes it ideal for emergency room determination of PCP.

DAWN: Drug Abuse Warning Network or Data About Worthless Numbers?

This report presents further data about toxicologic results in 1008 "mentions" to the DAWN (Drug Abuse Warning Network) System from Los Angeles County/USC Medical Center in 1977. Details from some of the blood concentrations found in that retrospective study are presented here for the most commonly reported drugs, both alone and in combination with alcohol. The data suggests caution about inferring drug abuse trends from DAWN data is presently collected.

Lidocaine efficacy and toxicity assessed by a new, rapid method.

Lidocaine (L) levels were measured by gas chromatography (GC) and a new technique of direct measurement by enzyme immunoassay (EMIT) in 50 consecutive patients admitted to the Coronary Care Unit who received L. There was no significant difference between the levels by the two techniques. There was eradication of most ventricular arrhythmias in 78% of patients, partial effectiveness in 16%, and no improvement in 6%. Toxicity was mainly mild central nervous system effects, noted in 26 of the 50 patients. All six patients with serum L above 5.9 microgram/ml had signs of toxicity. EMIT was found to be accurate and much faster than the traditional GC method.

The Drug Abuse Warning Network (DAWN) Program. Toxicologic verification of 1,008 emergency room 'mentions'.

One thousand eight emergency room patient records from which reports were contributed to the federal Drug Abuse Warning Network (DAWN) system from the Los Angeles County/University of Southern California Medical Center in 1977 were studied. The drugs reported to DAWN for these patients were compared with the available toxicology laboratory reports for some of these same patients. The purpose was to test the validity of the data reported to DAWN. Toxologic analyses had been performed on only 528 patients (52%) of the entire sample. Eighty percent of these tested had some positive toxicology result. The DAWN reports were verified in 20% of the tested sample, found to be incorrect in 11%, and partially correct or partially incorrect in 69%. Drugs identified toxicologically had varied concentrations, some below or within therapeutic range and some at toxic levels. This study suggests that the reliability of DAWN REPORTS SHOULD BE TESTed prospectively in an unbiased definitive material study.

Clinical evaluation of the EMIT procainamide and N-acetylprocainamide assay.

Procainamide and its major metabolite, N-acetylprocainamide, were measured by the homogeneous enzyme immunoassay technique (EMIT). The reagents for the EMIT assays were supplied as a separate matched set for each assay. There is no cross-reactivity by procainamide in the assay for N-acetylprocainamide or by N-acetylprocainamide in the assay for procainamide. Within-day precision determined by replicate analysis of samples in the therapeutic range gave a coefficient of variation of less than 5% for each assay. The day-to-day coefficient of variation was less than 6% for each assay. Quantitative results obtained by the enzyme immunoassay on serum samples from patients receiving procainamide were compared with the results obtained by a high pressure liquid chromatography procedure. For the procainamide assay the correlation coefficient (r) was 0.983; for the N-acetylprocainamide assay the correlation coefficient was 0.981. There was no false positives or false negatives. The immunoassay requires 50 microliters of serum and the enzyme activity is measured in a spectrophotometer. An individual determination requires only 1 min to perform; therefore, the procedure can be used for either emergency or routine analysis.

California Association of Toxicologists proficiency testing program.

A proficiency testing program that has been conducted by the California Association of Toxicologists for 10 years is described. The purpose of the program is to allow each participant the opportunity to evaluate their methodology and efficiency on a qualitative as well as quantitative basis with other laboratories in the organization. The program is conducted entirely on a volunteer basis with the sample prepared by a different member each time. The selection of drugs for inclusion in the sample, the preparation and distribution, and the collation and dissemination of the results are discussed. An evaluation of all aspects of the program is presented.

Toxicology test-ordering patterns in a large urban general hospital during five years: an update.

Analytical data from the clinical toxicology laboratory of a large urban hospital, the Los Angeles County--University of Southern California Medical Center, are reported for the year 1976 and are compared to similar data previously documented for the year 1972. Drugs assayed, number of tests requested, and number of positive results are collated. Data on 58 assays show that the overwhelming majority of the requests continue to be for those tests that were originally classified as tests with 4-h turn-around time in the patient-focused concept for a clinical toxicology service in 1972. Total workload increased by 70%. The number of patients on whom some toxicologic assay was requested doubled in spite of a decrease in the number of patients admitted to the hospital during this five-year period. The data show that assays for some socially and clinically significant drugs--ethanol diazepam, tricyclics, and phencyclidine--increased disproportionally while others remained relatively constant, or even decreased.