Muon-pair production by atmospheric muons in CosmoALEPH.

Data from a dedicated cosmic ray run of the ALEPH detector were used in a study of muon trident production, i.e., muon pairs produced by muons. Here the overburden and the calorimeters are the target materials while the ALEPH time projection chamber provides the momentum measurements. A theoretical estimate of the muon trident cross section is obtained by developing a Monte Carlo simulation for muon propagation in the overburden and the detector. Two muon trident candidates were found to match the expected theoretical pattern. The observed production rate implies that the nuclear form factor cannot be neglected for muon tridents.

Tertiary N-glucuronides of clozapine and its metabolite desmethylclozapine in patient urine.

In experiments with expressed human UDP-glucuronosyltransferase 1A4 (UGT1A4), the antipsychotic clozapine proved to be conjugated to two different glucuronides, one of which was identified as the quaternary ammonium glucuronide derivatized at the N-methylpiperazine group; this compound had previously been isolated from patient urine. An additional glucuronide produced in larger quantity was assumed to be conjugated at the secondary nitrogen of the central ring to form 5-N-glucuronide, but this was not proven. The analogous olanzapine 10-N-glucuronide was found to make a major contribution to urinary metabolites in human volunteers. In the present investigation, tertiary 5-N-glucuronides were isolated from incubations of clozapine and desmethylclozapine with human liver microsomes fortified with UDP-glucuronic acid, and their structures were confirmed by mass and (1)H NMR spectrometry. The same conjugates could also be purified from patient urine. Their approximate quantities in urine from four patients ranged between 0.1 and 0.5% of the dose, as did those of the quaternary ammonium glucuronide of clozapine. Analogous to olanzapine 10-N-glucuronide, the tertiary clozapine 5-N-glucuronide was resistant toward enzymatic hydrolysis but was labile under acidic conditions.

Isolation and identification of clozapine metabolites in patient urine.

Biotransformation products of the atypical neuroleptic clozapine were isolated from urine samples of three schizophrenic patients by solid-phase extraction, liquid-liquid extraction for the separation of unpolar and polar metabolites, and thin-layer chromatography followed by final purification by high-performance liquid chromatography. Their structures were elucidated by mass spectrometry and (1)H NMR spectroscopy and in some cases by enzymatic deconjugation. Besides the known metabolites desmethylclozapine, clozapine N-oxide, 8-deschloro-8-hydroxyclozapine, and 8-deschloro-8-hydroxydesmethylclozapine, the unpolar fraction contained 7-hydroxyclozapine and a compound in which the piperazine ring of clozapine was partially degraded to an ethylenediamine derivative. Novel metabolites identified in the polar fraction were the sulfate and glucuronide conjugates of 7-hydroxyclozapine N-oxide, 8-deschloro-8-hydroxyclozapine-O-glucuronide, and the O-glucuronide of N-hydroxydesmethylclozapine; further conjugates were tentatively identified as 9-hydroxydesmethylclozapine-O-sulfate and 6-hydroxyclozapine-O-sulfate. In addition, the previously described conjugates 7-hydroxydesmethylclozapine-O-sulfate, 7-hydroxyclozapine-O-glucuronide and -O-sulfate, 8-deschloro-8-hydroxydesmethylclozapine-O-glucuronide, and the quaternary ammonium glucuronide of clozapine were detected.

[How accurate is invasive blood pressure determination with fluid-filled pressure line systems?]. / Wie genau ist die invasive Druckmessung mit flüssigkeitsgefüllten Druckschlauchsystemen?

It has been discussed by other authors that clinically relevant mistakes can occur in the measurement of invasive blood pressure. For this reason, we investigated all pressure lines used in our hospital. Our studies showed that exact measurement of invasive blood pressure using fluid-filled pressure measuring systems is not possible in the arterial, venous or pulmonal-arterial areas. Iatrogen mistakes should be excluded by working carefully. Exact knowledge of the physical qualities and the dynamic response of the fluid-filled pressure line used is required for judging the measuring accuracy. In clinical practice, measurement errors can amount to 40%. An acknowledged method to verifying errors is the Gabarith system developed by Billiet and Colardyn, which can determine the extent of the biggest-possible error after investigating the pressure line. A reduction of measurement error to below 2% can be achieved by carefully combining the individual components of the measuring system and, if necessary, by using an industrially-produced damping device (resonance overshoot eliminator [R.O.S.E.]). In this way, standardized measuring systems can be made available for clinical practice.

Conjugation of the enantiomers of ketotifen to four isomeric quaternary ammonium glucuronides in humans in vivo and in liver microsomes.

The antiallergic drug ketotifen is chiral due to a nonplanar seven-membered ring containing a keto group. Earlier studies have revealed glucuronidation at the tertiary amino group as a major metabolic pathway in humans. Chemical synthesis of glucuronides from racemic ketotifen now led to four isomers separable by HPLC of which two each could be ascribed to (R)-(+)- and (S)-(-)-ketotifen by synthesis from the enantiomers. According to (1)H NMR analysis of the (S)-ketotifen N-glucuronides, the conformation of the piperidylidene ring differs between the two isomers. Enzymatic hydrolysis with Escherichia coli beta-glucuronidase proceeded at a lower rate with the slower eluting (S)-ketotifen glucuronide than with the three other isomers. On incubation of the ketotifen enantiomers (0.5-200 microM) with human liver microsomes in the presence of UDP-glucuronic acid and Triton X-100, the N-glucuronides of (R)-ketotifen were produced with an apparent K(M) 15 microM and V(max) 470 pmol/min/mg protein. The two (S)-ketotifen glucuronides were formed by two-enzyme kinetics with K(M1) 1.3 microM and K(M2) 92 microM and V(max) values of 60 and 440 pmol/min/mg protein. After ingestion of 1 mg of racemic ketotifen, 10 healthy subjects excreted in urine 17 +/- 5% of the dose in the form of N-glucuronides. The (R)-ketotifen glucuronide isomers contributed one-sixth only, whereas the remainder consisted primarily of the (S)-ketotifen glucuronide isomer, which eluted last. Differential hydrolysis or membrane transport may be responsible for the discrepancy between N-glucuronide isomer ratios in vitro and in vivo.

Disposition and chemical stability of telmisartan 1-O-acylglucuronide.

Telmisartan 1-O-acylglucuronide, the principal metabolite of telmisartan in humans, was characterized in terms of chemical stability and the structure of its isomerization products was elucidated. In addition, pharmacokinetics of telmisartan 1-O-acylglucuronide were assessed in rats after i.v. dosing. Similar to other acylglucuronides, telmisartan 1-O-acylglucuronide and diclofenac 1-O-acylglucuronide, which was used for comparison, showed the formation of different isomeric acylglucuronides on incubation in aqueous buffer. The isomeric acylglucuronides of telmisartan consisted of the 2-O-, 3-O-, and 4-O-acylglucuronides (alpha,beta-anomers). First order degradation half-lives of 26 and 0. 5 h were observed on incubation in buffer of pH 7.4 for the 1-O-acylglucuronides of telmisartan and diclofenac, respectively. This indicated that the 1-O-acylglucuronide of telmisartan was among the most stable acylglucuronides reported to date. The high stability of telmisartan 1-O-acylglucuronide was confirmed by in vitro experiments that indicated only very low covalent binding of telmisartan acylglucuronide to human serum albumin but a considerable amount of covalently bound radioactivity with the acylglucuronide of diclofenac. After i.v. dosing to rats, telmisartan 1-O-acylglucuronide was rapidly cleared from plasma with a clearance of 180 ml/min/kg, compared with 15.6 ml/min/kg for the parent compound. Because telmisartan 1-O-acylglucuronide exhibited a comparably high chemical stability together with a high clearance that resulted in low systemic exposure, the amount of covalent binding to proteins should be negligible compared with other frequently used drugs, such as furosemide, ibuprofen, or salicylic acid.

Meloxicam: metabolic profile and biotransformation products in the rat.

1. The metabolic fate of 14C-labelled meloxicam was investigated in the urine and bile of rat following oral and intraduodenal administration. Structural elucidation of metabolites was performed by nuclear magnetic resonance, mass spectrometry (electron impact and fast atom bombardment). 2. A mean total of 76.3% 14C-radioactivity was recovered in urine over 96 h, with the remainder in the faeces. The metabolic pattern in the excreta was independent of dose (1 versus 10 mg/kg) and collection period (0-8 versus 24-48 h). In bile one of the main metabolites was absent. 3. Meloxicam underwent extensive metabolism with only small amounts of unchanged drug recovered in the urine (< 0.5%) or bile (4.5%). Principal routes of biotransformation were: oxidation of the 5-methyl group of the N-heteroaryl-carbamoyl side chain to yield the 5'-hydroxymethyl derivative (33% of metabolites in urine, 22% in bile) and the 5'-carboxy derivative (16% in urine, 49% in bile). Oxidative cleavage of the benzothiazine-ring yielded an oxamic acid metabolite in urine (23.5%), which was not present in bile. 4. The introduction of a methyl-group into the N-heteroaryl-carbamoyl side chain increased lipophilicity and facilitated metabolic excretion compared with structurally related compounds.

Quaternary N-glucuronides of 10-hydroxylated amitriptyline metabolites in human urine.

1. Conjugated metabolites were isolated from the urine of patients receiving amitriptyline treatment using a combination of solid-phase extraction, h.p.l.c. and t.l.c. 2. By n.m.r. and mass spectrometry, N-glucuronides of E- and Z-10-hydroxyamitriptyline and of trans-10,11-dihydroxyamitriptyline were identified in addition to the previously described O-glucuronides of E- and Z-10-hydroxyamitriptyline and -nortriptyline and amitriptyline-N-glucuronide. 3. The quaternary ammonium glucuronides proved to be resistant to acid hydrolysis, but could be cleaved enzymatically. 4. In urine samples from three patients, 35-60% of conjugated 10-hydroxyamitriptyline was found in the form of N-glucuronides. 5. A volunteer given an i.v. infusion of amitriptyline-N-glucuronide excreted E- and Z-10-hydroxyamitriptyline-N-glucuronide; following ingestion of E-10-hydroxyamitriptyline its N-glucuronide could be measured in urine.

Glucuronides of hydroxylated metabolites of amitriptyline and nortriptyline isolated from rat bile.

Polar conjugates were isolated from the bile of rats given amitriptyline (AT, unlabeled or labeled with 14C), nortriptyline (NT), or 10-hydroxy (10-OH) derivatives of the drugs. The procedure involved extraction on a column of polystyrene resin, elution with methanol, and separation by preparative TLC followed by reversed phase HPLC. Individual metabolites were characterized by NMR spectroscopy and fast atom bombardment mass spectrometry and by enzymatic or acid deconjugation with subsequent identification of aglycones and glucuronic acid. Conversely, they were compared with conjugates obtained from hydroxy compounds by incubation with rat liver microsomes and UDP-glucuronic acid. Glucuronides isolated from the bile of rats given AT were derived from 2-OH-AT, (E)- and (Z)-10-OH-AT, 2-hydroxy-3-methoxy- (or 3-hydroxy-2-methoxy) AT, 10, 11-(OH)2-AT, and some of the N-demethylated analogues of these compounds. In most cases, 10-OH compounds form two diastereoisomeric glucuronides produced from the enantiomeric alcohols; 10, 11-(OH)2 metabolites occur as cis- and trans-isomers that are conjugated with glucuronic acid. Administration of synthetic (E)- and (Z)-10-OH-AT and -NT leads to the excretion of their glucuronides along with conjugates formed after demethylation and/or introduction of a second OH group. NT gives rise to 2-OH-NT glucuronide besides those conjugates derived from (E)-10-OH-NT. No glutathione conjugates could be detected.

Phenolic metabolites of amitriptyline and nortriptyline in rat bile.

Anesthetized bile fistula rats received amitriptyline (AT), its N-oxide (AT-NO), or nortriptyline (NT) at doses of 72 mumol/kg ip, and bile was collected for 6-9 hr. Isolation of metabolites was achieved by enzymic deconjugation and repeated TLC of extracted aglycones. Purified compounds were characterized by UV, NMR, and mass spectrometry, by color reactions, and by chemical interconversions. Besides the alcohols E-10-hydroxy-AT and 10,11-dihydroxy-AT, the phenol E-2-hydroxy-AT occurred as a major AT metabolite, while 2,10- and 2,11-dihydroxy-AT, 2,10,11-trihydroxy-AT, and 2-hydroxy-3-methoxy (or 3-hydroxy-2-methoxy)-AT were present in smaller quantities. Further minor metabolites were 2-hydroxy-11-oxo-AT, 3-hydroxy-AT, 3,11-dihydroxy-AT, and its dehydration product 3-hydroxy-10,11-dehydro-AT. The exact position of the functional groups was elucidated by the nuclear Overhauser effect (NOE) in NMR spectroscopy and by analyzing metabolite patterns in the bile of rats given E- or Z-10-hydroxy-AT. Administration of AT-NO led to a larger proportion of methylated catechols and a smaller one of 10-hydroxy metabolites. Besides the tertiary amines, rats given AT or AT-NO excreted the demethylated analogues of some of the hydroxylation products. The latter also occurred as metabolites of NT, the ratio of aromatic and aliphatic hydroxylation being lower than with AT or AT-NO. Urine of rabbits treated orally with AT contained mono- and dihydroxylated metabolites resulting from attack at positions 2, 3, 10, and/or 11 and the same methylated catechols as rat bile.

Phenolic metabolites of chlorprothixene in man and dog.

From urine and feces of dogs and urine of patients given chlorprothixene (CPT) per os, metabolites were extracted without or with enzymatic deconjugation and separated by repeated TLC. Purified compounds were characterized by UV, NMR, and mass spectrometry, by color reactions, and by chemical interconversions. Both species excreted 6- and 7-hydroxy-CPT besides the sulfoxide and demethylated analogues. In urine, the phenols were largely present as conjugates. The major metabolites in dog feces were 5-hydroxy-CPT and its demethylated derivative, whereas 5-hydroxylation was not detected in man. Dog excrete also contained 6-hydroxy-7-methoxy (or 7-hydroxy-6-methoxy)-CPT; further, a 5-hydroxy compound was detected in which the exocyclic double bond was hydrated. In the other metabolites, the Z-configuration of CPT had been retained, but small quantities of E-isomers were formed during isolation. According to preliminary quantitative data, phenols accounted for a small part of extractable metabolites in human urine, whereas they predominated in dog feces.

[Studies on the biotransformation of fominoben-HCl in man (author's transl)]. / Untersuchungen zum Metabolismus von Fominoben-HCl beim Menschen.

The biotransformation of 3'-chloro-2'-(N-methyl-N-[(morpholino-carbonyl)methyl]aminomethyl)benzanilide hydrochloride (fominoben-HCl, PB 89 Cl, Noleptan) was investigated in man. The most substantial metabolites were quantified. The metabolite patterns of fominoben in urine and plasma are compared. Fominoben, is rapidly and extensively metabolized to many metabolites. At the time of the maximum plasma level. 2 h after an oral dose of 160 mg of 14C-PB 89 Cl, only 1.5% of the plasma radioactivity can be measured as the unchanged initial compound. No parent compound can be found in the urine, only in the stool some traces of fominoben can be detected. The biotransformation can be characterized by four main pathways: 1. cleavage reactions, 2. hydroxylations, 3. cyclisations, 4. conjugations. The reactions 1--3 proceed as well simultaneously as successively.