Cocaine disposition in humans after intravenous injection, nasal insufflation (snorting), or smoking

The disposition of radiolabeled cocaine in humans has been studied after three routes of administration: iv injection, nasal insufflation (ni, snorting), and smoke inhalation (si). Metabolism, followed by urinary excretion of metabolites, proved to be the major route of elimination in all cases. Hydrolytic products (benzoylecgonine, ecgonine methyl ester) were the major excretion products. Benzoyl ecgonine was generally most prevalent, but after smoking two subjects excreted larger amounts of ecgonine methyl ester and the ratio of the two compounds averaged lower in subjects who smoked cocaine. Low binding of cocaine to plasma proteins was observed and blood to plasma ratios were essentially unity. The volume of distribution of cocaine is low (2.70 liter/kg for V beta). Absorption of smoked cocaine was rapid (half-time of 1.1 min). Absorption after ni was slower (half-time of 11.7 min). After iv injection, a rapid distribution phase was observed (half-life of 11 min) and the elimination half-life was 78 min. In 16 subjects divided into three groups based on routes, the half-life based on the average rate constant was 69 min. Bioavailability was good after ni (80%). Undecomposed cocaine from si was well absorbed, but observed bioavailability was diminished by degradation from heating.

Confirmation of cannabis use. II. Determination of tetrahydrocannabinol metabolites in urine and plasma by HPLC with ECD

Simultaneous determination of delta 9-tetrahydrocannabinol (THC) and its major metabolites--11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) and 11-hydroxy-delta 9-tetrahydrocannabinol (11-OH THC)--in urine and plasma by HPLC with electrochemical detection (LC/EC) was studied. After biological fluids were hydrolyzed, samples were extracted with an automatic extractor and analyzed by LC/EC. HPLC was carried out with a reversed-phase silica C8 column and a mobile phase of acetonitrile/methanol/0.02N H2SO4 (35:15:50) at 1.8 mL/min. Coefficients of variation at 10-500 ng/mL of THC metabolites were 2.19-5.91%. The detection limit was under 0.5 ng/mL (S/N greater than 3). Time course of excretion of THC and THC-COOH in rabbit urine was studied. THC-COOH could be detected until 216 h after administration. By this method, urine samples of suspects arrested in Japan were tested.

Interaction between marihuana and ethanol: effects on psychomotor performance

This is a report of the results of a placebo-controlled study in which the effects of the interaction between ethanol and marihuana on drug plasma concentrations, subjective ratings of intoxication, heart rate acceleration, and psychomotor performance were investigated. Six healthy, male, paid volunteers, moderate users of ethanol and marihuana, participated in the study. Ethanol (0.42 g/kg, 0.85 g/kg, or placebo) was administered over a 30-min interval. Fifteen minutes later the subjects smoked, in their customary manner, NIDA cigarettes containing 2.4% or 0.0004% (placebo) delta-9-tetrahydrocannabinol (THC). Each subject was tested in a single-blind, latin-square crossover design with the following six conditions: placebo ethanol/placebo marihuana; low dose ethanol/placebo marihuana; high dose ethanol/placebo marihuana; placebo ethanol/marihuana; low dose ethanol/marihuana; and high dose ethanol/marihuana. The variables measured in the study were: (a) subjective rating of ethanol and/or marihuana intoxication; (b) heart rate; (c) accuracy and latency of response in the Simulator Evaluation of Drug Impairment (SEDI) task; (d) blood ethanol concentration by gas chromatography; and (e) plasma concentration of THC by radioimmunoassay. The results indicate that the decrements due to ethanol in performance of skills necessary to drive an automobile were significantly enhanced by marihuana in an additive and perhaps synergistic manner. The administration of ethanol prior to marihuana smoking did not produce significant effects on the subjective rating of "high," heart rate acceleration, or THC plasma concentration.

Mammogram interpretation by physician assistants

The objective of this study was to determine whether a health maintenance organization (HMO) desirous of providing low-cost, quality mammography could employ physician assistants (PAs) to interpret mammograms under the supervision of HMO radiologists. After intensive training in mammographic interpretation, four PAs individually interpreted 727 mammograms of 470 normal breasts, 75 breasts with benign breast masses, and 182 breasts with cancer. The interpretations by the PAs were more sensitive and as specific as those made by six HMO radiologists who interpreted the same cases, and as effective as those by radiologists described in the literature. In receiver-operating-characteristic curve analysis, the areas under curves for PAs were larger than those under curves for radiologists. Interpretations by PAs took less time and cost less than did those by radiologists; the dispositions recommended by PAs were similar to those recommended by radiologists. We conclude that properly trained, evaluated, and supervised PAs can interpret mammograms. Legal, practical, and ethical considerations dictate that this can best be accomplished under the direction of radiologists who are well trained in mammography.

Evidence that "vaginal peptidase" is a bacterial gene product

A peptidase has been described in vaginal samples, termed "vaginal peptidase." This enzyme has been proposed as a tissue specific marker for vaginal debris. We have explored the presence of this enzyme in vaginal swabs from alleged sexual assault victims and volunteer donors as well as bacterial cultures. These studies reveal that "vaginal peptidase" is composed of a family of peptidase isozymes that originate from several bacterial species. The characterization of "vaginal peptidase" as a tissue specific marker for vaginal debris is premature.

Pharmacokinetics of pentobarbital enantiomers as determined by enantioselective radioimmunoassay after administration of racemate to humans and rabbits

Radioimmunoassays were developed for R- and S-pentobarbital. The optical isomers of pentobarbital were individually alkylated to N-crotonic acid analogs that were coupled to bovine serum albumin. Immunization of rabbits with the conjugates, which were enantiomerically pure at the asymmetric' carbon of the pentobarbital moiety, led to formation of antisera that selectively bound the predicted enantiomer. In displacement studies with enantiomerically pure radioligands, the opposite enantiomer showed 1.0 to 1.4% cross-reaction. Similar selective binding was observed for enantiomers of secobarbital, thiopental and thiamylal. Assays were developed and used to determine enantiomer pharmacokinetics in rabbits and humans given racemic pentobarbital. In rabbits, difference in clearance of the two isomers was minimal, the result of a slightly larger volume of distribution of the R-enantiomer combined with a slightly higher value of the elimination rate constant beta for the S-enantiomer. In humans, the volume of distribution was 12% greater for the R-enantiomer, but the value of beta was 14% higher for this isomer as well. Thus, the median clearance of the S-enantiomer (1.96 liters/h) was 25% less than that of the R-isomer (2.58 liters/h). The S-enantiomer was also more strongly protein bound in plasma (73.5% vs 63.4% for the R-enantiomer), which is consistent with its structural congruence to S-warfarin, S-phenprocoumon and S-glifumide.

Resident and faculty differences in student evaluations: implications for changes in a clerkship grading system

Data were collected for 163 students completing a surgical clerkship including scores on patient write-ups, ward performance evaluations, oral examinations, and National Board of Medical Examiners (NBME) Surgery subscores. Oral examination scores and patient write-ups were rated from 74 (failing) to 100 (honors) by faculty members. The ward performance evaluation included ratings on nine components of ward performance from 1 (unsatisfactory) to 4 (superior) and an overall ward score of 74 (failing) to 100 (honors). Similarities and discrepancies in the way that evaluators viewed clerks were found. Weights given to ward component ratings in relationship to the overall ward score were equivalent for faculty members and residents. Residents rated clerks higher than faculty members on five ward components. Faculty ratings were poorly correlated with resident ratings. Faculty members and residents gave different ratings to the same students in contrast to the similarities in which faculty members and residents gave weight to the ward component ratings. Resident ratings were better than faculty ratings in predicting the NBME Surgery subscore. Although these results suggest that residents are better evaluators of a clerk's performance than are faculty members, other studies indicated the opposite. The elimination of participation of either faculty or residents in the grading of students is unwise. Periodic monitoring of evaluation practices is necessary to ensure fairness in grading procedures.

Paired-ion liquid chromatographic method for the analysis of a phenanthrenemethanol antimalarial in whole blood

A sensitive and specific high-performance liquid chromatographic (HPLC) assay was developed for the determination of the candidate antimalarial (+/-)-(1,3-dichloro-6-trifluoromethyl-9-phenanthryl)-3-di-(n-butyl )aminopropanol hydrochloride in whole blood. A reversed-phase, paired-ion (lauryl sulfate) system achieved separation of the antimalarial and internal standard from interfering constituents with a sensitivity limit of 10 ng/mL by UV detection (254 nm). Chromatographic variables (counterion concentration, pH, and column temperature) were examined to determine their effect on assay characteristics (retention, efficiency, and relative response) in clinical analysis. The antimalarial was isolated from 2.0 mL of whole blood using overnight extraction with 30% ethyl acetate in hexane followed by an acid/base partition sequence to remove major interferences. Overall recovery for the antimalarial was 84% with a CV of 5.0%, and the recovery of the internal standard was 81% (CV = 3.6%). The assay was validated by analysis of both intra- and interlaboratory samples. The assay was applied to the analysis of whole blood samples taken from a 30-year-old healthy human male who had received a single 14.1-mg/kg oral dose. The stability of the antimalarial in whole blood for up to 4 months and in sample extracts for up to 34 d at -17 degrees C was also demonstrated.

Pyrolysis products of heroin

Heating of heroin hydrochloride or of heroin at 250 degrees C led to extensive degradation. Major components of the pyrolysate were identified as heroin, 6-acetylmorphine, N,6-diacetylnormorphine, and N-acetylnorheroin by comparison of mass spectra and 13C- and 1H-nuclear magnetic resonance (NMR) spectra with those of authentic compounds. There was evidence for degradation of the piperidino moiety and the structure 3,4-diacetoxyphenanthrene was proposed for a minor product.

Naltrexone disposition in man after subcutaneous administration

The metabolism, excretion, and pharmacokinetics of [15,16-3H2]naltrexone were studied in six human males after sc administration of the hydrochloride salt. Biological fluids were analyzed by a combination of high performance liquid chromatography with liquid scintillation measurement of radioactivity. After administration, naltrexone was rapidly absorbed into the systemic circulation. The mean absorption rate constant was 0.091 +/- 0.008 min-1 (half-life of 7.6 min). In general the metabolic, excretory, and pharmacokinetic patterns for naltrexone were similar to those observed after iv administration of naltrexone to man. The terminal phase plasma rate constant was 0.413 +/- 0.035 hr-1 (half-life of 1.68 hr) for parent drug and 0.0786 +/- 0.0090 hr-1 (half-life of 8.8 hr) for the major metabolite, 6 beta-naltrexone. An average of 76 +/- 6% (+/- SD) of the total radioactivity was recovered in the urine within 72 hr after administration. Naltrexone was found in the urine in both the free (3.4 +/- 0.8% of dose) and conjugated (6.8 +/- 2.1% of dose) form. 6 beta-Naltrexol was present in urine largely in the unconjugated form (28 +/- 7% of dose) but the conjugated form was also found (12 +/- 3% of dose).

Evaluation of immunoassays for cannabinoids in urine

A comparison was made of several cannabinoid urine assays. Two hundred randomly selected urine specimens were initially screened by two enzyme immunoassays (EMIT-st and EMIT-d.a.u.) and a radioimmunoassay (Abuscreen RIA). Selected specimens found positive by any of these methods were further analyzed by gas-liquid chromatography with flame ionization detection (GLC/FID), gas chromatography/mass spectrometry (GC/MS), and an experimental RIA from Research Triangle Institute (RTI RIA). The GLC/FID method gave confirmations in 69 to 92% of the samples, depending on the method used and the cut-off employed. GC/MS confirmed 98% of the EMIT and RIA positives using a low cut-off (20 ng/mL). All RIA positives at 100 ng/mL were confirmed by GC/MS. There was complete agreement between the RTI RIA and the EMIT assays, but not with the Abuscreen RIA at the 100 ng/mL cut-off. The study illustrates that care must be exercised in establishing assay cut-offs and the designation of false positive results.

Effect of influenza vaccine on warfarin anticoagulation

Recent studies have indicated that viral infections, influenza vaccination, or drugs that increase interferon synthesis all decrease hepatic drug metabolism. We report a case in which influenza vaccination was temporally related to an increased anticoagulant effect of warfarin. A prospective study evaluating the effect of influenza vaccination on the prothrombin time of eight patients anticoagulated over the long term showed that there was prolongation of prothrombin time of 40%. In a second study, the effect of influenza vaccination on warfarin t1/2 was determined in healthy subjects. No significant effect on warfarin metabolism was observed after vaccination. We conclude that influenza vaccination is associated with increased anticoagulant response in some patients receiving anticoagulants over a long term. This effect appears to be related to some step in the coagulation pathway and not to decreased warfarin metabolism and a subsequent rise in serum concentration.

Identification of in vitro rat metabolites of 1-phenylcyclohexene

In vitro metabolites of 1-phenylcyclohexene produced by the 10,000g supernatant fraction from rat liver homogenates were identified by a combination of spectrometric, chromatographic, and synthetic techniques. Initial oxidation occurred in the 3-position of 1-phenylcyclohexene to yield 1-phenyl-1-cyclohexen-3-one and 1-phenyl-1-cyclohexen-3-ol. Further allylic oxidation at the 6-position occurred to form 1-phenyl-6-hydroxy-1-cyclohexen-3-one and 1-phenyl-1-cyclohexene-3,6-diol. Trans-1-phenyl-1-cyclohexene-3,4-diol was also found and may have resulted from hydroxylation of 1-phenyl-1-cyclohexen-3-one alpha to the carbonyl to yield 4-hydroxy-1-phenyl-1-cyclohexen-3-one (not isolated) followed by carbonyl reduction. Oxidation of the double bond also occurred to give the cis and trans isomers of 1-phenylcyclohexane-1,2-diol as well as a compound postulated to be 1-phenylcyclohexane-1,2,3-triol.

Phencyclidine disposition in humans after small doses of radiolabeled drug

Administration of small doses of radiolabeled phencyclidine hydrochloride (PCP X HCl) to normal volunteers has resulted in basic information on the disposition of PCP in humans. The drug and its metabolites were excreted mainly in the urine whether it was given orally or i.v. (73 +/- 4% of dose was recovered in urine after i.v. administration of 1 mg), with very little fecal excretion (3-5%) and some excretion in sweat. Oral bioavailability was 72 +/- 8%. Major metabolic pathways found involved hydroxylation of the cyclohexane and piperidine rings followed by conjugation. Oxidation to an aminopentanoic acid also occurred. PCP and phenylcyclohexene were inhaled when PCP was smoked. For PCP the weighted mean apparent terminal rate constant (beta) was 0.0395 +/- 0.0008 h-1 for 16 subjects, equivalent to a half-life of 17.6 h, but 2 subjects had half-lives of over 2 days. The volume of distribution (Vd, beta) was 6.2 +/- 0.3 liters/kg. At usual urinary pH, PCP excretion represented less than 10% of total clearance, but marked lowering of urinary pH can significantly increase the contribution of renal clearance to overall clearance.

Urine pH and phencyclidine excretion

Subeffective doses (0.5 mg) of 3H-phencyclidine (PCP) were given intravenously to three healthy men under two regimens designed to alkalinize or acidify their urine (oral sodium bicarbonate or ammonium chloride). The concentrations of PCP and its metabolites in saliva, plasma, and urine for 7 hr after injection were determined by high-performance liquid radiochromatography. A sample of perspiration from one subject was analyzed. The effects of physical exercise on the plasma concentration and urinary excretion of PCP were also studied. Multiple linear regression analysis showed the logarithm of renal clearance the renal clearance of PCP. PCP and its metabolites are also excreted in perspiration. Our results support clinical reports of the importance of vigorous acidification of urine and diuresis in treatment of PCP intoxication.

Free-base cocaine smoking

Six healthy male, paid subjects smoked 50 mg of free-base cocaine in a specially designed glass pipe under a rigidly controlled smoking protocol. The method of heating the pipe and the temperature that produced the most efficient and consistent vaporization of the drug had been determined experimentally. The psychological and cardiovascular effects of smoking free-base cocaine were recorded. Approximately 26% of th original material was recovered from the pipe after smoking. Simulated smoking experiments in vitro indicated that only 44% of the material not trapped in the pipe was cocaine and that over 90% of this cocaine was delivered during the first four puffs (i.e., during the first 2 min of simulated smoking). These findings indicate that of the original 50 mg of cocaine free base placed in the pipe's bowl, only 32% could have been inhaled (16.3 +/- 0.6 mg). The cocaine free base inhaled induced psychological and cardiovascular effects similar to, or slightly more intense and pleasurable than, the effects of 20 mg of cocaine HCl (18 mg of cocaine base) taken intravenously by the same subjects and also induced a slightly more intense craving for another dose.

Comparison of effects of marihuana cigarettes to three different potencies

Marihuana cigarettes containing 1.32%, 1.97%, and 2.54% delta 9-tetrahydrocannabinol (THC) were smoked by six experienced marihuana users at weekly intervals in a double-blind cross-over design under laboratory conditions. Puff duration, number of puffs taken, duration of inhalation holding, interval between puffs, and duration of smoking were recorded for each cigarette smoked. The portion of each cigarette remaining after smoking was weighed and analyzed to determine THC content. Subjective ratings of the "high" achieved and the heart rate acceleration induced by smoking the marihuana were measured. The plasma concentrations of THC and of its principle metabolite, 11-nor-delta 9-THC-9-carboxylic acid (9-carboxy THC), were determined by radioimmunoassay of blood samples drawn at frequent intervals for 6 hr. The results indicate that, irrespective of the potency of the marihuana, the pattern of smoking was much the same. The magnitude of the subjective high, heart rate acceleration, THC, and 9-carboxy THC plasma concentrations were proportional to potency. This dose response was particularly clear between the 1.32% and the 2.54% cigarettes. Peak plasma concentrations of THC consistently occurred 7 to 8 min after initiation of smoking and declined thereafter despite continued smoking for another 6 to 10 min. Peak subjective high and peak heart rate acceleration occurred several minutes after the end of smoking and at a considerable interval after maximal THC plasma concentrations were reached.

Phencyclidine disposition after intravenous and oral doses

[3H]-Phencyclidine (PCP) hydrochloride was given in intravenous (0.1 or 1 mg) or oral (1 mg) doses to male subjects. After 1 mg IV, drug and metabolites were recovered in urine (72.8 +/- 4.0% of dose), feces (4.7 +/- 0.9%), and perspiration. Fecal excretion was low (3.4 +/- 0.4%) after oral dosing and oral bioavailability was estimated at 72%. PCP comprised 16% of urinary radioactivity with 31% consisting of enzymatically hydrolyzable conjugates of hydroxylated metabolites. Both cis and trans isomers of 4-phenyl-4-(1-piperidinyl)cyclohexanol were found. Maximum average plasma PCP concentrations of 2.7 to 2.9 ng/ml were observed after oral and intravenous 1-mg doses. Blood/plasma ratios were approximately 1.0 and plasma binding was about 65%. Parent drug was found in saliva. Apparent terminal phase half-lifes averaged 21 +/- 3 hr (harmonic mean 17 hr, range 7 to 46 hr). The volume of distribution averaged 6.2 +/- 0.3 l/kg. Renal clearances were variable, but the average was 9% of the total clearance. Thus, PCP is cleared principally by metabolism.