[Rapid simultaneous determination of 42 psychoactive drugs and their metabolites in human plasma and urine by ultra performance liquid chromatography-tandem mass spectrometry].

A rapid method for the simultaneous determination of 42 psychoactive drugs and their metabolites (barbitals, benzodiazepines, tricyclic antidepressants, phenothiazines, etc. ) in human plasma and urine was developed using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). After a simple protein precipitation step, the analysis of the drugs and the metabolites was achieved on an Acquity UPLC BEH C18 column by using the gradient elution with ammonium acetate and methanol-acetonitrile (1: 1, v/v) as the mobile phases, and detected by electrospray ionization-tandem mass spectrometry in the multiple reaction monitoring (MRM) mode operated simultaneously in both positive and negative modes by rapid switching, and quantified by matrix-match standard solution. The average recoveries were 60.2% - 125% and 64.5% - 126% for the drugs in plasma and urine except those of perphenazine, thioridazine and chloropromazine in plasma were 37.6% - 57.5%, 36.3% - 48.3%, 52.4% -67.4%, respectively; trazodone and diazepam in urine were 100% -142% and 108% - 177%, respectively. The relative standard deviations (RSDs) of all the drugs in plasma and urine were within 0.8% - 26% and 2.6%18% (n = 6), respectively. The detection limits of the 4 barbitals ranged from 20 to 100 mg/L and those of the other drugs ranged from 0.05 to 2.0 mg/L. The method is simple, selective and sensitive to detect drugs for both clinical and forensic purposes.

Determination of barbiturates in urine by micellar liquid chromatography and direct injection of sample.

A liquid chromatographic procedure for the determination of six barbiturates (barbital, diallyl barbituric acid, phenobarbital, butabarbital, amobarbital and pentobarbital) in urine samples is described. The proposed system uses a Spherisorb octadecyl-silane ODS-2 C18 analytical column and a guard column of similar characteristics. The UV detector was set at 240 nm. A study to select adequate composition of the micellar mobile phase for the separation of these compounds in urine samples is performed. Maximum resolution was achieved with a 0.07 M sodium dodecylsulphate-0.3% propanol at pH 7.4 eluent. Limits of detection at 240 nm were ranged between 0.13 microg ml(-1) for diallyl barbituric acid and 2.7 microg ml(-1) for amobarbital. The procedure allows for the determination of these compounds in 20 minutes, it does not require prior a sample preparation step and it can be very useful to the investigation of intoxication.

A comparative study of uranyl nitrate and cisplatin-induced renal failure in rat.

Renal dysfunction can have substantial effects on the pharmacokinetics and pharmacodynamics of drugs. A wide variety of animal models have been developed in an attempt to mimic conditions seen in human renal failure. In reality, no single animal model would be completely satisfactory because the etiology and development of renal failure are diverse. During recent years injection of uranyl nitrate has been found to be the most effective and easiest method to produce renal dysfunction in laboratory animals. Changes over the last 10 years in government regulations on the production and use of radioactive substances make the compound less available. There is, therefore, a need for a more accessible compound comparable to uranyl nitrate as an inducer of renal failure. The present study compares the effects of another known nephrotoxin, cisplatin, with uranyl nitrate in the rat. Cisplatin was chosen because of its ability to produce kidney damage and its identical site and mechanism of action on the kidneys as uranyl nitrate. In the present study, rats were given different i.v. doses of uranyl nitrate or cisplatin dissolved in 0.9% of saline solution. The effects of nephrotoxins were evaluated on the basis of changes in body weight, creatinine and blood urea nitrogen (BUN) concentrations. It was found that the degree of renal damage produced by uranyl nitrate and cisplatin is a function of the administered dose. With increasing dose there is evidence of more severe kidney damage, as measured by substantially increased plasma concentrations of creatinine and BUN. The time required to return to normal creatinine and BUN concentrations was also a function of dose. Furthermore, plasma alanine aminotransferase (ALT) activity was measured as an index of hepatocellular damage. The ALT test showed that a single dose does not affect the liver function. From dose-response curves a dose of 4 mg/kg body weight of uranyl nitrate or cisplatin was chosen to produce acute renal failure in animals for pharmacokinetic study of barbital. Barbital (100 mg/kg) was administered on the fifth day (the day of maximum renal dysfunction) to uranyl nitrate, cisplatin-treated and control rats. The elimination rate constant (k), elimination half life (t1/2), volume of distribution at steady state (Vss), total (CLt) and renal clearance (CLr) were significantly different in treated groups of rats from control, however no such difference was detected between uranyl nitrate and cisplatin-treated group of rats. In short, cisplatin is comparable to uranyl nitrate in producing renal failure in the rat and can be considered a suitable alternative.

A case of barbiturate poisoning with a readily-accessible laboratory reagent.

We report a patient with barbiturate intoxication due to surreptitious ingestion of barbital buffer from a clinical laboratory. Although detected in the urine toxicology screening test using an immunologic technique, this agent was not recognized in the more specific serum analysis done by gas-liquid chromatography. Barbital buffer is an effective long-acting sedative-hypnotic and is widely available from the laboratory shelf. It may not be reported by very specific analytical methods.

Barbital N-glucoside is not detected as a urinary excretion product of barbital in humans.

A study was undertaken to determine if humans excreted barbital N-glucoside as a urinary metabolite following oral administration of barbital. A liquid chromatography method using gradient elution was developed for detecting and quantifying barbital N-glucoside and barbital in urine. Following a single oral dose of barbital to male caucasian and oriental subjects that had previously been shown to excrete amobarbital and phenobarbital N-glucosides, no barbital N-glucoside conjugate was observed in the urine. This result indicates that N-glucosylation of barbiturates is not a general pathway for the biodisposition of barbiturates in man.

Disulfiram enhances pharmacological activity of barbital and impairs its urinary elimination.

Disulfiram or diethyldithiocarbamate significantly enhanced the sleeping time induced by barbital in rats. At identical time intervals after rats were injected with barbital the concentration of barbital in the blood or brain of animals that had previously received disulfiram was significantly higher than the concentrations in the corresponding tissues of control animals. Urinary excretion of barbital was significantly reduced in disulfiram-treated animals.

Identification of drugs using a gas chromatography-mass spectrometry system equipped with electron impact-chemical ionization and electron impact-field ionizationfield desorption combination sources.

In a case of toxicological analysis by gas chromatography (GC)-mass spectrometry-data system, chemical ionization (CI), field ionization (FI) and electron impact data are shown to lead rapidly to assignments for all significant GC peaks. Valuable data include not only full spectra in the three ionization modes, but also exact mass measurements in the FI or CI mode. Such measurements, obtained by a dynamic peak-matching technique, lead to the elemental composition of the compounds of interest. This knowledge makes the assignment of key GC peaks unequivocal and provides an extremely high level of confidence regarding the identity of whole metabolite series. It is also shown that the nature of the FI information is very similar to that obtained from CI data.

Effect of alpha tocopherol (vitamin E) deficiency on intestinal transport of passively absorbed drugs.

Alpha tocopherol (vitamin E) deficiency has been shown to cause changes in membrane structure. The present study relates alpha tocopherol deficiency with increased rates of transport and absorption of passively absorbed drugs. The pharmacokinetics of barbital in alpha tocopherol-deficient and control rats was studied. The barbital absorption rate constant in deficient animals increased compared to control values. This findings indicates that alpha tocopherol deficiency affects the intestinal membrane structure. This finding was confirmed by studying the intestinal transport of phenolsulfonphthalein, barbital, and salicylate using the everted gut technique. Phenolsulfonphthalein was transported more rapidly through the alpha tocopherol-deficient gut, but this difference was not significant after 30 min, probably due to membrane decomposition. Barbital, which is more lipid soluble and less dependent on changes in pore volume and size, was transported more rapidly through the deficient gut during the entire experiment. The transport rate of salicylate was not altered by the deficiency state. This result was expected since the drug is normally rapidly transported; therefore, comparatively small changes in permeability such as those induced by alpha tocopherol deficiency would be masked. After the oral administration of phenolsulfonphthalein to intact animals, a significantly higher amount of drug was recovered in the urine of the deficient group.

Barbital overdose and abuse.

Bailey, David N., and Jatlow, Peter I.: Barbital overdose and abuse. A new problem. Am J Clin Pathol 64:291-296, 1975. The unusual epidemiology and toxicology of barbital overdose and abuse are demonstrated by eight recent cases. Since barbital is used primarily in laboratory buffers and is not available as a prescription or over-the-counter drug in the United States, barbital overdose and abuse have until recently been rare. In several instances the barbital was stolen from a clinical or research laboratory. Serum concentrations were often "astronomically" high compared with those of other barbiturates, including phenobarbital. Concentrations severalfold greater than would be considered lethal for other barbiturates were consistent with survival, and all patients, including one with a serum concentration of 120.2 mg per dl. (higher than any previously reported), recovered with only conservative therapy (no peritoneal or hemodialysis). Patients could be awakened when the concentration was less than 16.0 mg per dl. Serum barbiturate concentrations greater than 20.0 mg. per dl. in a living patient should warrant serious consideration of barbital ingestion. In addition to the eight overdoses, 16 abusers of barbital were detected during 1974 by drug-abuse screening of urine.

Random urine analyses from drug addicts in a methadone treatment programme.

Random testing of urine from opiate addicts in the methadone treatment programme at the Drug Dependency Service, Brisbane Street, Sydney, was carried out for 18 months. Six samples from each of approximately 100 clients (that is, 580 specimens) have been analysed. It was found that clients receiving high methadone dosages (80 mg and over) used illegal opiates significantly less frequently than those on lower dosages. Furthermore, a decline in the use of illegal opiates and an increase in the proportion of "clear" urine specimens (that is, clear of all drugs except methadone) were indicators of the effectiveness of the methadone programme. It was concluded that urine testing was a useful and objective means of evaluating methadone or any other drug addiction treatment programme, and of monitoring what other drugs were being taken, both consciously or inadvertently in combinations. The results of urine testing can also be of value to counsellors in the therapeutic situation.