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.

Elevated norharman plasma levels in alcoholic patients and controls resulting from tobacco smoking.

Plasma norharman and harman levels were measured by solvent extraction and HPLC with fluorescence detection in alcohol-dependent patients undergoing in-patient abstinence treatment and in control subjects. In both groups, randomly collected samples from smokers contained higher mean norharman levels than those from non-smokers. In three volunteers norharman concentrations rose sharply after smoking of one or two cigarettes and declined to near-basal levels within one hour after one cigarette. When 12 patients kept a smoking-free interval of at least 6 h, they had similarly low plasma norharman concentrations (20 +/- 8 pg/ml) as 18 non-smoking control subjects (17 +/- 8 pg/ml) or as 13 smoking controls who had abstained from smoking (20 +/- 6 pg/ml). Ten of the patients smoked one cigarette and within 5-10 min attained norharman levels of 177 +/- 147 pg/ml plasma. The high prevalence of smokers among chronic alcoholics probably explains the previous finding of elevated norharman plasma levels in these patients.

Urinary dolichol--a doubtful marker of alcoholism.

The purpose of this study was to replicate the results of Pullarkat and Raguthu and Roine et al. who found elevated levels of urinary dolichol (long-chain 2,3-dihydropolyprenols) in chronic alcoholic patients. We investigated a sample of 21 alcohol-dependent inpatients voluntarily entering detoxification treatment. Urinary dolichol was only slightly increased as compared to 21 healthy controls. When dolichol was related to urinary creatinine no differences between alcoholic patients and controls could be found. Under conditions of confirmed abstinence the slightly elevated levels of dolichol returned to normal within 2 weeks. Compared with the sensitivity of gamma-glutamyltransferase which ranges from 72-85%, the value of urinary dolichol (sensitivity 9-19%) as a biochemical marker of alcoholism must be doubted.

[Serum levels of pyridostigmine in myasthenia gravis: methods and clinical significance]. / Serumspiegel von Pyridostigmin bei Myasthenia gravis: Methoden und klinische Bedeutung.

Correlation studies on patients with myasthenia gravis are reported in which clinical assessment of fatigue and neurophysiological findings are compared to blood levels of pyridostigmine. Measurements using a high-pressure liquid chromatography method (HPLC), give reproducible results. The levels of pyridostigmine in the serum or plasma of healthy controls and of patients show no essential differences. Components of coffee, tea, chocolate and cigarettes can markedly disturb the chromatography by adding additional peaks, so that interpretation becomes difficult or impossible. Blood levels can be measured approximately one hour after oral intake of 60 mg pyridostigmine. Concentrations rise for two to four hours and then decline exponentially. The half-life of pyridostigmine was between 156 and 210 minutes. Despite identical oral dosages, the concentration differed intraindividually and interindividually among patients. While the blood level does not reach its maximum value for 1-1 1/2 to 3 hours, the maximum clinical and neurophysiological effect of pyridostigmine appears 30-60 minutes after ingestion. Variable distribution of cholinesterase inhibitors over the different compartments (blood, synaptic region) is assumed to cause this temporal lag. If the total amount of pyridostigmine is divided into 4-5 doses, the concentration profiles over the course of a day are relatively stable. There is no significant correlation between the variations in blood level throughout one day, and changes in myasthenic symptomatology. Effects of pyridostigmine can be measured at levels as low as 5 ng/ml; at levels above 40 ng/ml further improvement can be detected only rarely. Blood levels were lower if corticosteroids were administered simultaneously; azathioprine had no influence on blood levels. Blood levels assays allow better differentiation of cholinergic and myasthenic crises and the identification of disturbed absorption and interactions with other medications.

Do urinary MHPG and plasma drug levels correlate with response to amitriptyline therapy?

Twenty-nine inpatients with primary affective disorder were treated with 150 mg amitriptyline (AT) daily for 28 days. Pretreatment urinary excretion of 3-methoxy-4-hydroxyphenylglycol (MHPG) was measured in two or three 24-h urine samples. Plasma levels of AT and nortriptyline (NT) were determined after 14, 21, and 28 days of treatment. MHPG excretion was significantly correlated with clinical response to treatment. Responders defined by two different methods showed higher pretreatment MHPG excretion than nonresponders. Correspondingly, high MHPG excretors (median split) showed significantly more improvement than low excretors. These relationships were even more apparent when possibly incomplete urine samples (creatinine excretion below 1000 mg/24h) were excluded. The high and low MHPG subgroups did not significantly differ from each other in their plasma levels of AT, NT, or AT plus NT. A significant rank correlation between clinical response and plasma levels of AT and/or NT did not exist, but there was a trend towards lower levels in responders.

4-methoxy-3-hydroxyphenylglycol as an internal standard for the determination of 3-methoxy-4-hydroxyphenyglycol in urine: results obtained in depressed patients and healthy controls.

A modification of the method developed by Dekirmenjian & Maas (1970) Anal. Biochem. 35, 113-122) is described for the determination of 3-methoxy-4-hydroxyphenylglycol in urine. The use of 4-methoxy-3-hydroxyphenylglycol as an internal standard improves the accuracy, simplicity and reproducibility. Therefore, the method is suitable for routine determination in laboratories without gas chromatography/mass spectrometry equipment. Some results obtained in depressed patients and healthy controls are presented.