Development and Validation of an LC-MS-MS Method for the Detection of 40 Benzodiazepines and Three Z-Drugs in Blood and Urine by Solid-Phase Extraction

An analytical method for the detection of 40 benzodiazepines, (±)-zopiclone, zaleplon and zolpidem in blood and urine by solid-phase extraction liquid chromatography-tandem mass spectrometry was developed and validated. Twenty-nine of 43 analytes were quantified in 0.5 mL whole blood for investigating postmortem, drug-facilitated sexual assault (DFSA) and driving under the influence of drugs cases (DUID). The four different dynamic ranges of the seven-point, linear, 1/x weighted calibration curves with lower limits of quantification of 2, 5, 10 and 20 μg/L across the analytes encompassed the majority of our casework encountered in postmortem, DFSA and DUID samples. Reference materials were available for all analytes except α-hydroxyflualprazolam, a hydroxylated metabolite of flualprazolam. The fragmentation of α-hydroxyflualprazolam was predicted from the fragmentation pattern of α-hydroxyalprazolam, and the appropriate transitions were added to the method to enable monitoring for this analyte. Urine samples were hydrolyzed at 55°C for 30 min with a genetically modified β-glucuronidase enzyme, which resulted in >95% efficiency measured by oxazepam glucuronide. Extensive sample preparation included combining osmotic lysing and protein precipitation with methanol/acetonitrile mixture followed by freezing and centrifugation resulted in exceptionally high signal-to-noise ratios. Bias and between-and within-day imprecision for quality controls (QCs) were all within ±15%, except for clonazolam and etizolam that were within ±20%. All 29 of the 43 analytes tested for QC performance met quantitative reporting criteria within the dynamic ranges of the calibration curves, and 14 analytes, present only in the calibrator solution, were qualitatively reported. Twenty-five analytes met all quantitative reporting criteria including dilution integrity. The ability to analyze quantitative blood and qualitative urine samples in the same batch is one of the most useful elements of this procedure. This sensitive, specific and robust analytical method was routinely employed in the analysis of >300 samples in our laboratory over the last 6 months.

Detailed quantum mechanical studies on bioactive benzodiazepine derivatives and their adsorption over graphene sheets

Estazolam (Z1) and related derivatives, adinazolam (Z2), alprazolam (Z3), 4-hydroxyalprazolam (Z4) and triazolam (Z5) have been studied by using various computational tools to analyze their geometry and spectral characteristics. The compounds were found to interact with graphene monolayer results shows that there is enhancement in various physico-chemical descriptors and surface enhanced Raman spectra (SERS). The various reactive descriptors obtained from the FMO analysis predict the reactive nature of the compound. The various lone pair/sigma to pi conjugation was analyzed using NBO formalism, which provides valuable information about intra molecular electron transfer which is vital in predicting the inherent stability of the molecule. Simulated electronic spectra using TD-DFT and CAM-B3LYP functional are discussed in detail with respect to electronic transitions and light harvesting efficiency. Suitability of candidates as a photo sensitizer in dye sensitized solar cells was studied and 4-Hydroxyalprazolam is identified as a suitable candidate. Nucleophilic and electrophilic regions of the molecules are identified using MESP, which adds to the reactivity information. It can be seen that the highest interaction energy has been obtained in the case of the Z5-graphene system, while the lowest interaction energy has been obtained in the case of the Z1-graphene system. Docking indicates that the ligands adsorbed over graphene also form stable complexes with the receptors as indicated by the high binding affinity energy values.

LC-MS/MS analysis of 13 benzodiazepines and metabolites in urine, serum, plasma, and meconium

We describe a single method for the detection and quantitation of 13 commonly prescribed benzodiazepines and metabolites: alpha-hydroxyalprazolam, alpha-hydroxyethylflurazepam, alpha-hydroxytriazolam, alprazolam, desalkylflurazepam, diazepam, lorazepam, midazolam, nordiazepam, oxazepam, temazepam, clonazepam and 7-aminoclonazepam in urine, serum, plasma, and meconium. The urine and meconium specimens undergo enzyme hydrolysis to convert the compounds of interest to their free form. All specimens are prepared for analysis using solid-phase extraction (SPE), analyzed using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), and quantified using a three-point calibration curve. Deuterated analogs of all 13 analytes are included as internal standards. The instrument is operated in multiple reaction-monitoring (MRM) mode with an electrospray ionization (ESI) source in positive ionization mode. Urine and meconium specimens have matrix-matched calibrators and controls. The serum and plasma specimens are quantified using the urine calibrators but employing plasma-based controls. Oxazepam glucuronide is used as a hydrolysis control.

Quantitation of benzodiazepines in blood and urine using gas chromatography-mass spectrometry (GC-MS)

The benzodiazepine assay utilizes gas chromatography-mass spectrometry (GC-MS) for the analysis of diazepam, nordiazepam, oxazepam, temazepam, lorazepam, alpha-hydroxyalprazolam, and alpha-hydroxytriazolam in blood and urine. A separate assay is employed for the analysis of alprazolam. Prior to solid phase extraction, urine specimens are subjected to enzyme hydrolysis. The specimens are fortified with deuterated internal standard and a five-point calibration curve is constructed. Specimens are extracted by mixed-mode solid phase extraction. The benzodiazepine extracts are derivatized with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSFTA) producing tert-butyldimethyl silyl derivatives; the alprazolam extracts are reconstituted in methanol without derivatization. The final extracts are then analyzed using selected ion monitoring GC-MS.

Metabolic interaction between ethanol, high-dose alprazolam and its two main metabolites using human liver microsomes in vitro

Alprazolam is widely used as a short-acting antidepressant and anxiolytic agent and its effect appears at very low doses while ethanol is used as a social drug worldwide. Sometimes, toxic interactions occur following combined administration of these two drugs. In this study we have investigated the interaction between ethanol and high-dose alprazolam using human liver microsomes in vitro. The interaction effects between ethanol and alprazolam were examined by a mixed-function oxidation reaction using a human liver microsomal preparation. Alprazolam and its two main metabolites (alpha-hydroxyalprazolam: alpha-OH alprazolam, 4-hydroxyalprazolam: 4-OH alprazolam) were measured by HPLC/UV. The production of 4-OH alprazolam, one main metabolite of alprazolam, was weakly inhibited by higher dose of ethanol, but not alpha-OH alprazolam. These results using a human liver microsomal preparation show that the production of 4-OH alprazolam is weakly inhibited by ethanol but not alpha-OH alprazolam. Toxic levels may be reached by simultaneous administration of ethanol and high-dose alprazolam.

Inhibition of CYP3A4 and CYP3A5 catalyzed metabolism of alprazolam and quinine by ketoconazole as racemate and four different enantiomers

OBJECTIVE

The antifungal drug ketoconazole (KTZ) is known as an inhibitor of, especially, the CYP3A subfamily, which catalyzes the metabolism of a large variety of drugs. Interactions between KTZ and CYP3A substrates have been reported both in vivo and in vitro. Most of them, however, involved the KTZ racemate. KTZ racemate and the separate enantiomers, 2R,4R; 2R,4S; 2S,4S, and 2S,4R, were evaluated for their selectivity in inhibiting alprazolam and quinine metabolism.

METHODS

The inhibition of alprazolam and quinine metabolism was studied in an in vitro system of human liver microsomes (HLM), recombinant of CYP3A4 and CYP3A5. The concentrations of formed 3-hydroxyquinine and 4- and alpha-hydroxyalprazolam were measured by HPLC and LC-MS, respectively.

RESULTS

Quinine 3-hydroxylation was catalyzed to a similar extent by CYP3A4 and CYP3A5. The formation rate of 4-hydroxyalprazolam was higher than that of alpha-hydroxyalprazolam for each HLM, CYP3A4 and CYP3A5. KTZ racemate and enantiomers showed differential inhibitory effects of quinine and alprazolam metabolism. Quinine metabolism catalyzed by HLM, CYP3A4 and CYP3A5 was potently inhibited by the trans-enantiomer KTZ 2S,4S, with IC(50) value of 0.16 microM for HLM, 0.04 microM for CYP3A4 and 0.11 microM for CYP3A5. The same enantiomer showed the lowest IC(50) values of 0.11 microM for HLM and 0.04 microM for CYP3A5 with respect to alprazoalm 4-hydroxylation and also the same pattern for alprazolamalpha-hydroxylation, 0.13 microM for HLM and 0.05 microM for CYP3A5. Alprazolam metabolism (both alpha- and 4- hydroxylations) catalyzed by CYP3A4 was inhibited potently by the cis-enantiomer KTZ 2S,4R, with IC(50) values of 0.03 microM.

CONCLUSIONS

Alprazolam and quinine metabolism is catalyzed by both CYP3A4 and CYP3A5. The present study showed that different KTZ enantiomers inhibit CYP3A4 and CYP3A5 to different degrees, indicating that structural differences among the enantiomers would be related to their inhibitory potency on these two enzymes.

Alprazolam as a probe for CYP3A using a single blood sample: pharmacokinetics of parent drug, and of alpha- and 4-hydroxy metabolites in healthy subjects

OBJECTIVES

(1) To determine the pharmacokinetic parameters of alprazolam and its two metabolites in plasma from healthy volunteers; (2) to identify a suitable single time point to take a plasma sample for CYP3A phenotyping.

METHODS

Twelve healthy Swedish volunteers received a single oral dose of 1 mg alprazolam. Blood samples were collected before drug intake and frequently up to 72 h thereafter. A liquid-chromatography/mass-spectrometry (LC/MS) method was used for the quantification of alprazolam, and 4- and alpha-hydroxyalprazolam.

RESULTS

The interindividual variation in the area under the concentration-time curve (AUC) was two, three and fourfold for alprazolam, 4-hydroxyalprazolam and alpha-hydroxyalprazolam, respectively. Plasma concentration ratios collected between 1 h and 48 h for both alprazolam/4-hydroxyalprazolam and alprazolam/alpha-hydroxyalprazolam correlated significantly to the corresponding AUC0-infinity ratios.

CONCLUSIONS

The metabolic ratios of alprazolam to respective metabolite in a single plasma sample at 3-24 h are suggested to reflect the alprazolam 4- and alpha-hydroxylation activities. In future, it will be important to study these activities in populations where CYP3A5, in addition to CYP3A4, is expressed at a high frequency and to clarify the relative importance of the two enzymatic pathways for in vivo clearance of alprazolam.

Simultaneous quantification of alprazolam, 4- and α-hydroxyalprazolam in plasma samples using liquid chromatography mass spectrometry

A sensitive and specific method was developed for quantification of alprazolam and its two metabolites 4-hydroxyalprazolam and alpha-hydroxyalprazolam in plasma. The work up procedure was solid phase extraction. Liquid chromatography-mass spectrometry (LC-MS) was used for separation, detection and quantification of the analytes. The limit of quantitation (LOQ) was 0.05 ng/mL for alprazolam and the two metabolites. The extraction recovery was more than 82% for alprazolam and its metabolites. The within- and between-assay coefficients of variation were in the range of 1.9-17.9%. The method was used for determination of the pharmacokinetics parameters of alprazolam and its two metabolites in healthy Caucasian subjects who ingested 1mg of alprazolam.

Quantitation of alprazolam and alpha-hydroxyalprazolam in human plasma using liquid chromatography electrospray ionization MS-MS

A sensitive and specific electrospray ionization high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) method has been developed for the quantitative determination of alprazolam (AL) and alpha-hydroxyalprazolam (OH-AL) in plasma. After the addition of deuterium labeled internal standards of AL and OH-AL, plasma samples were buffered to alkaline pH and extracted with toluene/methylene chloride (7:3). Dried extract residues were reconstituted in HPLC mobile phase and injected onto a reversed-phase C18 HPLC column. The analytes were eluted isocratically at a flow rate of 250 microL/min using a solvent composed of methanol and water (60:40) containing 0.1% formic acid. The analyses were performed using selected reaction monitoring. The assay was sensitive to 0.05 ng/mL for both the parent drug and metabolite and linear to 50 ng/mL. The intra-assay percent coefficients of variation (%CV) for AL at 2, 5, and 20 ng/mL were all < or = 5.6. At these concentrations, and all OH-AL intra-assay %CVs were < or = 8.4. The interassay variabilities for AL were 11.8%CV, 8.7%CV, and 8.7%CV at 2.0, 5.0, and 20.0 ng/mL, respectively. The OH-AL interassay variabilities were 9.6%CV, 9.2%CV, and 7.8%CV at the same concentrations, respectively. The assay accuracy was less than or equal to +/- 6.6% for both analytes at the three concentrations. The method was used to quantitate AL and OH-AL in plasma samples collected from 10 subjects who were administered a 1-mg oral dose of AL. The mean AL concentration peaked at 11.5 ng/mL 1 h after the dose and AL was detectable for 48 h. The mean OH-AL concentration peaked at 0.18 ng/mL 4 h after the dose and was undetectable by 36 h. Hydrolysis of the plasma samples had little effect on the detected AL concentrations but increased OH-AL concentrations substantially. Plasma/blood ratios for AL and OH-AL exceeded 1 in the study samples.

A fatality due to alprazolam intoxication

Alprazolam is one of the most widely prescribed benzodiazepines in the United States. It is generally considered a safe and effective drug for the treatment of anxiety disorders and panic attacks. Few overdoses that are due to the sole ingestion of alprazolam have been reported. This paper documents a fatality due to alprazolam intoxication and describes the distribution of alprazolam and an active metabolite, alpha-hydroxyalprazolam, in tissues obtained at autopsy. Qualitative identification of the drugs was achieved by full-scan gas chromatography-mass spectrometry, and quantitative analysis was performed by high-performance liquid chromatography. High concentrations of alprazolam were found in all specimens analyzed, but the metabolite was detected only in subclavian blood, urine, bile, and liver. A postmortem heart blood alprazolam concentration of 2.1 mg/L is the highest reported in the literature to date.

Determination of alprazolam and alpha-hydroxyalprazolam in human plasma by gas chromatography/negative-ion chemical ionization mass spectrometry

A sensitive and specific method was developed for the determination of alprazolam and its major metabolite alpha-hydroxyalprazolam in plasma. After the addition of deuterium-labeled internal standards, plasma samples were buffered to pH 9 with 1 ml of saturated sodium borate buffer, extracted with toluene-methylene chloride (7:3) and evaporated to dryness. The residues were treated with N,O-bis(trimethylsilyl)trifluoroacetamide containing 1% of trimethylchlorosilane and analyzed on a Finnigan-MAT mass spectrometer operated in the negative-ion chemical ionization mode with methane as the reagent gas. Chromatographic separation was achieved on a Restek-200 capillary column using hydrogen as the carrier gas. The assay was linear from 0.25 to 50 ng ml-1 for both compounds. The intra-assay precision for alprazolam was 16.1% at 0.5 ng ml-1 and 4.6% at 50 ng ml-1 and that for alpha-hydroxyalprazolam was 15.8% at 0.5 ng ml-1 and 4.2% at 50 ng ml-1. The method was used to determine alprazolam and alpha-hydroxyalprazolam in human plasma samples collected after a single 2 mg oral does of alprazolam. A peak concentration of 32.9 ng ml-1 of alprazolam was detected at 1 h following the dose.

Comparative evaluation of five immunoassays for the analysis of alprazolam and triazolam metabolites in urine: effect of lowering the screening and GC-MS cut-off values

This study included evaluation of five commercially available immunoassays for the detection of alprazolam and triazolam metabolites in urine following single oral doses of these drugs. The products investigated were the EMIT d.a.u. assay, EMIT II assay, Abbott TDx (FPIA) assay, Bio Site TRIAGE device, and the Boehringer Mannheim/Microgenics CEDIA assay for urinary benzodiazepines. Urine specimens were also analyzed quantitatively by gas chromatography-mass spectrometry. Percent cross-reactivity was assessed by analysis of drug free urine containing drug standards at concentrations ranging from 100 to 10,000 ng/mL. The drug standards analyzed were alpha-OH-alprazolam, alpha-OH-triazolam, and alpha-OH-alprazolam glucuronide. The effect of lowering the screening cut-off value to 100 ng/mL, lowering the confirmation cut-off value to 50 and 25 ng/mL and the use of beta-glucuronidase hydrolysis prior to analysis was also studied. Lowering the screening cut-off value and using enzymatic hydrolysis prior to screening increased the positive detection rate for benzodiazepines with the EMIT d.a.u. assay and fluorescence polarization immunoassay (FPIA). The TRIAGE device gave the lowest percent cross-reactivity in the analysis of the drug standards and gave negative results in all urine specimens analyzed following ingestion of alprazolam and triazolam.

Urinary screening for adinazolam and its major metabolites by the Emit d.a.u. and FPIA benzodiazepine assays with confirmation by HPLC

Adinazolam is a triazolobenzodiazepine, currently under clinical investigation, that possesses antidepressant and anxiolytic activity. It has a short half-life (less than 3 h), and less than 2% of an oral dose is excreted unchanged. The major urinary metabolite is N-desmethyladinazolam, and minor metabolites are estazolam and alpha-OH-alprazolam. The objective of this study was to characterize the reactivity of adinazolam, N-desmethyladinazolam, and estazolam in the Emit d.a.u. benzodiazepine assay and the Abbott TDx urine (FPIA) benzodiazepine assay. N-desmethyladinazolam and estazolam gave an equivalent response to the Emit cutoff calibrator (300 ng/mL) at 100-200 ng/mL, and adinazolam gave an equivalent response at 200 ng/mL. By FPIA, N-desmethyladinazolam and adinazolam had equivalent net polarization values as the 300-ng/mL low control at 500-1000 ng/mL, and estazolam gave a positive response at 300 ng/mL. Six volunteers received single oral doses of 10, 30, and 50 mg of adinazolam. Urine specimens (N = 7) were collected from 0 to 36 h post-administration. By Emit, all urine specimens at all doses were positive from 2 to 36 h, and all FPIA analyzed specimens were positive from 2 to 24 h. Confirmation testing was performed by HPLC by analyzing for N-desmethyladinazolam. All urine specimens were confirmed positive for N-desmethyladinazolam (greater than 200 ng/mL) except for the blank specimens (time = 0) and 7 of 18 specimens collected 36 h post-administration. In conclusion, both immunoassay screening assays are acceptable for detecting the presence of adinazolam in human urine for up to 24 h after a single oral dose of 10-50 mg.

Urinalysis of alpha-hydroxyalprazolam, alpha-hydroxytriazolam, and other benzodiazepine compounds by GC/EIMS

This procedure was developed as an overall benzodiazepine confirmation scheme and includes the detection of the most important urinary analytes encountered by clinical toxicology laboratories in North America: alpha-hydroxyalprazolam, alpha-hydroxytriazolam, 2-hydroxyethylflurazepam, oxazepam, temazepam, and lorazepam. Desmethyldiazepam (nordiazepam) was not targeted because it is metabolized to oxazepam. This procedure takes advantage of beta-glucuronidase hydrolysis for analysis of intact benzodiazepine molecules, oxazepam-2H5 as an internal standard, a newly developed extraction solvent, and a silylating moiety that may be more sensitive than trimethylsilyl (-TMS) derivatives, the tertbutyldimethylsilyl (-TBDMS) derivative. For all compounds the extraction efficiency was greater than 90% and the limit of quantitation (LOQ at a S/N of 10) was less than 10 ng/mL. Coefficients of variation for a 200-ng/mL control were less than 5% and less than or equal to 11% for within-run and between-run trials, respectively. Of 13 human specimens screened by EMIT and most with self-reported histories, alpha-hydroxyalprazolam was found in seven (range 49-1264 ng/mL), oxazepam was found in five (72-3897 ng/mL), and lorazepam (476 ng/mL), 2-hydroxyethylflurazepam (2301 ng/mL), and alpha-hydroxytriazolam (106 ng/mL) in one each.

Alprazolam in end-stage renal disease: I. Pharmacokinetics

In a double-blind, randomized, placebo-controlled study, the pharmacokinetics of alprazolam and its active metabolite, alpha-hydroxyalprazolam, were determined in 12 normal subjects and 12 dialysis patients [7 hemodialysis (HD) patients and 5 continuous ambulatory peritoneal dialysis (CAPD) patients]. Blood samples were collected over 48 hours after alprazolam 0.5 mg and alprazolam 2 mg administration. Alprazolam and alpha-hydroxyalprazolam concentrations and alprazolam free fraction were determined. The pharmacokinetics of alprazolam were similar in normal subjects and HD patients with the exception of higher free fraction in HD patients. Differences were detected, however, in the pharmacokinetics of alprazolam in CAPD patients when compared with normal subjects and HD patients. These differences included a higher free fraction and a lower apparent oral clearance and free clearance in CAPD patients than in normal subjects or in HD patients. There was also a tendency for a later Tmax and a longer elimination half-life in CAPD patients than in normal subjects or HD patients. Alpha-hydroxyalprazolam concentrations were less than 15% of corresponding alprazolam concentrations in normal subjects and dialysis patients. Thus, end-stage renal disease is associated with changes in absorption, distribution, and/or elimination of alprazolam.

Caffeine-induced anxiogenesis: the role of adenosine, benzodiazepine and noradrenergic receptors

The purpose of this study was to determine the mechanism by which caffeine increases anxiety. Rats were tested in the social interaction test of anxiety after administration of caffeine (20 or 40 mg/kg) alone or in combination with various compounds. In order to investigate the role of adenosine receptors, caffeine was given in combination with 2-chloroadenosine (0.1 and 1 mg/kg). To investigate the role of benzodiazepine receptors, chlordiazepoxide (5 mg/kg), a benzodiazepine antagonist, flumazenil (RO 15-1788, 1 and 10 mg/kg) and a triazolobenzodiazepine U-43,465 (32 mg/kg) were used. Finally, an alpha 2-receptor agonist, clonidine (0.1 and 0.025 mg/kg) and a beta-adrenoceptor antagonist, DL-propranolol (5 mg/kg), were used to study the role of noradrenergic systems in the effects of caffeine. Caffeine (20 and 40 mg/kg) reduced the time spent in social interaction and this effect was antagonized by chlordiazepoxide, U-43,465 and DL-propranolol, but not by flumazenil, 2-chloroadenosine or clonidine. It was therefore concluded that the anxiogenic effect of caffeine was unlikely to be due to its effects at adenosine or benzodiazepine receptors. It is suggested that the reversal of caffeine's effects by chordiazepoxide may have been "functional," i.e., merely a cancellation of two opposite effects. It is discussed whether the reversal of caffeine's effects by propranolol and U-43,465 are functional, or reflect a noradrenergic site of action.

Profiles of the antipanic compounds, triazolobenzodiazepines and phenelzine, in two animal tests of anxiety

Two animal tests of anxiety (the elevated plus-maze and the social interaction test) were used to investigate the effects of several antipanic agents. In the elevated plus-maze, the triazolobenzodiazepines adinazolam (2 and 5 mg/kg) and alprazolam (1 mg/kg), tested after 5 days of pretreatment, demonstrated significant anxiolytic effects, while phenelzine (9 mg/kg), after 21 days of pretreatment, demonstrated nonsignificant anxiolytic effects. In the social interaction test, the triazolobenzodiazepines generally did not produce an anxiolytic profile, and phenelzine even revealed significant anxiogenic activity. The antipanic agents therefore distinguish between the two tests of anxiety. The lack of a strong anxiolytic profile with these agents in both tests lends support to the distinction between generalized anxiety and panic disorder.

Triazolobenzodiazepines antagonize the effects of anxiogenic drugs mediated at three different central nervous system sites

The ability of the triazolobenzodiazepines to antagonize the anxiogenic effects of three different compounds in the social interaction test was investigated. The compounds were selected for their different sites of action in the central nervous system: FG 7142, acting at the beta-carboline site on the gamma-aminobutyric acid-benzodiazepine receptor complex; pentylenetetrazole, acting at the picrotoxin site on this complex, and yohimbine, an alpha 2-adrenoceptor antagonist. Adinazolam (5 mg/kg) and U-43,465 (32 mg/kg) were able to antagonize the anxiogenic effects of all three compounds, unlike classical 1,4-benzodiazepines, that are not able to antagonize the effects of yohimbine. The results are discussed in terms of the anti-panic activity of the triazolobenzodiazepines.

U-43,465F: a triazolobenzodiazepine with pronounced antidepressant-like as well as anxiolytic activities in animals

U-43,465F displays activity in a number of classical antidepressant assays in rodents. Mechanistically, it potentiates norepinephrine and blocks the uptake of this amine but not that of serotonin. It is not a monoamine oxidase inhibitor nor does it markedly enhance monamine release. In several behavioral assays based upon conditioned and non-conditioned behavioral suppression, U-43,465F displays anxiolytic properties. Thus this compound possesses both antidepressant-like and anxiolytic activities and may have a special utility in the treatment of depressive disorders.

U 43,465F: a benzodiazepine with antidepressant activity? Interaction with Ro 15-1788 and d,1-propranolol

U-43,465F (8-chloro-1-[2-(dimethylamino)ethyl]-6-phenyl-4H-s-triazolo [4,3-a][1,4]benzodiazepine p-toluene sulfonate) showed two fold activity at 32 mg/kg i.p.: antipunishment activity inhibited by the benzodiazepine receptor antagonist Ro 15-1788, and an antidepressant-like reversal of apomorphine-induced hypothermia, antagonized by the beta-adrenergic receptor blocker d,1-propranolol. U-43,465F hence produced effects not mediated by benzodiazepine receptors and these effects might be related to antidepressant activity.