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Biomedical subjects

L Bertilsson

Publications and source records attributed to L Bertilsson.

At least 145 records · Page 8Linked to original sources
PubMed1989

Disposition of perphenazine is related to polymorphic debrisoquin hydroxylation in human beings.

The pharmacokinetics of a single oral dose of 6 mg perphenazine was studied in a group of six slow and six rapid hydroxylators of debrisoquin. Peak serum concentrations of perphenazine were significantly higher in slow hydroxylators than they were in rapid hydroxylators (2.4 +/- 0.6 versus 0.7 +/- 0.3 nmol/L, p less than 0.001). The AUC(0-12) was also higher in slow hydroxylators than it was in rapid hydroxylators (18.5 +/- 6.2 versus 4.5 +/- 2.5 nmol.L-1.hr, p less than 0.001). The data suggest that the disposition of the antipsychotic drug perphenazine covaries with polymorphic debrisoquin hydroxylation.

Administration, Oral↗
PubMed1989

Importance of genetic factors in the regulation of diazepam metabolism: relationship to S-mephenytoin, but not debrisoquin, hydroxylation phenotype.

Single oral 10 mg doses of diazepam and demethyldiazepam were given on different occasions to 16 healthy subjects. The subjects included four poor hydroxylators of debrisoquin and three poor hydroxylators of mephenytoin. There was a correlation between the total plasma clearance of diazepam and demethyldiazepam (rs = 0.83; p less than 0.01). There was no relationship between benzodiazepine disposition and debrisoquin hydroxylation. Poor hydroxylators of mephenytoin had less than half the plasma clearance of both diazepam (p = 0.0008) and demethyldiazepam (p = 0.0001) compared with extensive hydroxylators of mephenytoin. The plasma half-lives were longer in poor hydroxylators than they were in extensive hydroxylators of mephenytoin for both diazepam (88.3 +/- SD 17.2 and 40.8 +/- 14.0 hours; p = 0.0002) and demethyldiazepam (127.8 +/- 23.0 and 59.0 +/- 16.8 hours; p = 0.0001). There was no significant difference in volume of distribution of the benzodiazepines between the phenotypes. This study shows that the metabolism of both diazepam (mainly demethylation) and demethyldiazepam (mainly hydroxylation) is related to the mephenytoin, but not to the debrisoquin, hydroxylation phenotype.

Adult↗
PubMed1989

S-mephenytoin hydroxylation phenotypes in a Swedish population determined after coadministration with debrisoquin.

Mephenytoin (100 mg) and debrisoquin (10 mg) were administered orally, both separately and together, to 41 healthy subjects. The ratios between the S and R enantiomers of mephenytoin and between debrisoquin and 4-OH-debrisoquin in urine were determined by use of GC. These ratios were used as measures of drug hydroxylation. There was no change in the phenotypic trait values of the two drugs when they were coadministered. Mephenytoin and debrisoquin then were coadministered to 253 healthy Swedish subjects, before bedtime, and urine samples were collected at periods of 0 to 8, 8 to 24, and 24 to 32 hours after drug administration. In the first sample, seven of the 253 subjects (2.8%, 95% confidence interval 0.8% to 4.8%) had an S/R ratio of greater than 0.8; this indicated that they were poor hydroxylators of S-mephenytoin. In the two consecutive samples, the S/R ratios of mephenytoin did not change in these seven persons, whereas it decreased to less than 0.2 in the third sample in the extensive hydroxylators. As was reported before, there was no relationship between the mephenytoin S/R ratio and the debrisoquin metabolic ratio (rs = 0.01). Coadministration of debrisoquin and mephenytoin before bedtime and urine collection during two consecutive nights allow for an accurate determination of both phenotypes in the population.

Adolescent↗
PubMed1989

Stereoselective disposition of racemic E-10-hydroxynortriptyline in human beings.

The disposition and elimination kinetics of the enantiomers of E-10-hydroxynortriptyline (E-10-OH-NT) were studied in six rapid and four slow hydroxylators of debrisoquin after a single oral dose of 75 mg racemic E-10-OH-NT hydrogen maleate. The plasma levels and the AUC of unconjugated (-)E-10-OH-NT were two to five times higher than those of (+)E-10-OH-NT. The plasma half-lives of both enantiomers were 8 to 9 hours. A significantly higher proportion of the given dose of (+)E-10-OH-NT (64.4% +/- 12.1%) than of (-)E-10-OH-NT (35.3% +/- 9.7%) was recovered in urine as glucuronide conjugate, but more (-)E-10-OH-NT was recovered unchanged in urine. The total oral plasma clearance and the metabolic clearance by glucuronidation were significantly (p less than 0.0001) higher for (+)E-10-OH-NT than for (-)E-10-OH-NT. The findings indicate that first-pass glucuronidation of E-10-OH-NT is enantioselective in human beings in vivo, with preference for (+)E-10-OH-NT. The renal clearance of unbound (-)E-10-OH-NT (0.57 +/- 0.16 L.kg-1.hr-1), on the other hand, exceeded that of (+)E-10-OH-NT (0.44 +/- 0.14 L.kg-1.hr-1) (p less than 0.005), which suggests enantioselective tubular secretion. The debrisoquin hydroxylation status was not associated with any of the investigated kinetic processes that relate to E-10-OH-NT.

Administration, Oral↗
PubMed1989

Diazepam treatment does not influence the debrisoquine or mephenytoin hydroxylation phenotyping tests.

Debrisoquine and S-mephenytoin hydroxylation phenotyping tests were performed in 9 patients before and during treatment with diazepam at a daily dose of 10 or 15 mg. There was no change in either the debrisoquine/4-hydroxydebrisoquine ratio or the ratio of S/R mephenytoin in urine. The hydroxylation of these two test drugs is apparently not inhibited by administration of therapeutic doses of diazepam.

Adult↗
PubMed1989

Fluoxetine treatment of depression. Clinical effects, drug concentrations and monoamine metabolites and N-terminally extended substance P in cerebrospinal fluid.

In an open study of depressed inpatients, the effects of the selective serotonin uptake blocker fluoxetine on 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), 4-hydroxy-3-methoxyphenyl glycol (HMPG) and N-terminally extended substance P (SP) in cerebrospinal fluid (CSF) were measured. Thirteen unmedicated patients who met the DSM-III criteria for major depressive episode were included, and 9 completed the study. During treatment the 5-HIAA concentration decreased by 46%. The HVA and HMPG concentrations also decreased significantly, but to a lesser degree. The mean level of N-terminally extended SP was unaffected by fluoxetine treatment, but the pretreatment level correlated significantly with the pretreatment level of HMPG. The pretreatment level of HVA was the only biochemically variable that appeared to predict therapeutic outcome. The plasma concentrations of both fluoxetine and its metabolite norfluoxetine increased significantly between 3 and 6 weeks. Plasma and CSF levels of both the parent drug and its active metabolite were correlated.

Adult↗
PubMed1989

Glucuronidation of amitriptyline in man in vivo.

The urinary excretion of amitriptyline (AT) as N-glucuronide was studied in healthy volunteers after single oral doses of AT and in patients on continuous treatment with AT. In the volunteers, 8 +/- 3% of a 25 mg dose of AT was recovered in urine as glucuronide during 108 hr. No difference between slow and rapid debrisoquine hydroxylators with respect to the excretion of AT glucuronide was seen. 0.08 to 1.68% of the given AT dose was recovered in urine in unchanged form. The excretion of unchanged AT correlated with the debrisoquine metabolic ratio (rs = 0.61; p less than 0.01). In 5 patients on continuous treatment with AT (125-150 mg/day), 8 +/- 5% of the daily dose was recovered in 24-hr urine as AT glucuronide. The present study shows that direct glucuronidation is a minor metabolic pathway of AT in man in vivo both after single low doses and during continuous treatment with therapeutic doses.

Administration, Oral↗
PubMed1988

Polymorphic debrisoquin hydroxylation in 757 Swedish subjects.

The metabolic ratios (MRs) between debrisoquin and 4-hydroxydebrisoquin in urine after a single oral dose of 10 mg debrisoquin were bimodally distributed in 757 healthy, white Swedish volunteers. Forty-one subjects (5.4%) had an MR greater than 12.6 and were classified as slow debrisoquin hydroxylators. The MR was reproducible in urine stored at +8 degrees C for 1 week and at -20 degrees C over a period of 5 years. Collection intervals of 6 or 12 hours gave the same MR. Intraindividual repeatability of the debrisoquin phenotyping test was established in 37 subjects examined twice at least 2 weeks apart. The calculated frequency of the single allele that is believed to control deficient debrisoquin hydroxylation is similar among white Swedish people, as among other white groups examined so far; however, it is significantly different from the frequency in certain Oriental groups. Detailed comparisons of the prevalence of slow debrisoquin hydroxylation in different ethnic groups are not possible due to shortcomings in current epidemiologic techniques used (small materials, the location of the antimode distinguishing rapid and slow hydroxylators unknown, and family studies missing).

Adolescent↗
PubMed1988

Alprazolam does not inhibit the metabolism of nortriptyline in depressed patients or inhibit the metabolism of desipramine in human liver microsomes.

In 10 patients treated with nortriptyline, the steady-state plasma concentrations of the parent drug and the active 10-hydroxy metabolite were very similar before and during concomitant treatment with alprazolam (0.5 mg orally t.i.d.). In human liver microsomes the 2-hydroxylation of desipramine was not inhibited by alprazolam. The absence of an inhibition by alprazolam on the hydroxylations of nortriptyline in vivo and of desipramine in vitro indicates that alprazolam is not metabolized by the debrisoquine hydroxylase.

Adult↗
PubMed1988

Enantioselectivity of 4-hydroxylation in extensive and poor metabolizers of debrisoquine.

Debrisoquine (DQ) has no chiral centre, but hydroxylation in position 4 leads to formation of an asymmetric carbon centre with two possible enantiomers, their absolute configuration being R(-) and S(+)-4-hydroxydebrisoquine (4-OHDQ). Since the absolute stereochemistry of the 4-hydroxylation of DQ in man is unknown, the enantioselectivity of this process was studied in panels of extensive (EM) and poor metabolizers (PM) of DQ. In EM subjects 4-hydroxylation of DQ leads almost exclusively to the formation of S(+)-4-OHDQ. In contrast, PM subjects were not only characterized by a decreased total 4-OHDQ formation but also a marked loss of enantioselectivity in product formation. Between 5 to 36% of total 4-OHDQ was excreted as R(-)-4-OHDQ.

Debrisoquin↗
PubMed1988

Effect of valpromide on the pharmacokinetics of carbamazepine-10, 11-epoxide.

The single oral dose pharmacokinetics of carbamazepine-10, 11-epoxide (CBZ-E) were investigated in six normal volunteers during a control session and during concurrent treatment with valpromide (VPM) (300 mg twice daily for 8 days). VPM caused a prolongation of the CBZ-E half-life from 6.4 +/- 1.4 to 20.5 +/- 6.3 h and decreased CBZ-E clearance from 73.5 +/- 20.0 to 23.5 +/- 4.0 ml h-1 kg-1 (P less than 0.01). These results suggest that the elevation of plasma CBZ-E levels in patients receiving carbamazepine and VPM in combination is due to inhibition of epoxide hydrolase in the liver.

Adolescent↗
PubMed1988

Detection of N-terminally extended substance P but not of substance P in human cerebrospinal fluid: quantitation with HPLC-radioimmunoassay.

A reversed-phase HPLC system was used to concentrate and separate components of substance P-like immunoreactivity (SP-LI) from human CSF. When CSF was injected and fractions collected, no SP-LI could be detected by radioimmunoassay (RIA) at the retention time of SP or SP-sulfoxide. Instead, SP-LI was detected in later eluting fractions. This SP-LI reacted with two different antisera raised against the C-terminal part of SP, but not with an antiserum against the N-terminal part. A compound with similar properties was also found to be present in neutral extracts of rat dorsal spinal cord. When the late-eluting compound from human CSF was treated with trypsin and rechromatographed on HPLC, an immunoreactive component eluting at the position of SP could be detected with both the C- and N-terminally directed SP antisera. These results suggest that an N-terminally extended form of SP is present in human CSF. Trypsinization also gave two other compounds with affinity for the N- but not the C-terminally directed antisera. This may indicate that N-terminal fragments of SP extended at the N-terminus or SP molecules extended at both the N- and the C-terminus (i.e., preprotachykinins) also are present in human CSF. In 32 CSF samples from depressed patients, SP-LI was determined with a C-terminally directed antiserum with and without prior HPLC separation. SP itself could not be detected, but the late-eluting form of SP-LI could be quantitated in all samples by combined HPLC-RIA. In most samples, there was a relatively good agreement between the SP-LI levels measured with and without HPLC.

Antibody Specificity↗
PubMed1988

Single-dose kinetics of an enteric-coated formulation of carbamazepine-10,11-epoxide, an active metabolite of carbamazepine.

The kinetics of an enteric-coated formulation of carbamazepine-10,11-epoxide (CBZ-E) were studied in healthy subjects. A single oral dose of 100 mg of CBZ-E was given to eight subjects. Four of them were also given a single oral dose of 200 mg of CBZ-E. Plasma concentrations of CBZ-E and urinary excretion of the end metabolite trans-10,11-dihydroxy-10,11-dihydro-carbamazepine (trans-CBZ-diol) were determined by high performance liquid chromatography. Plasma kinetics of CBZ-E fitted an open one-compartment model with plasma elimination half-life of 7.4 +/- 1.8 h (mean +/- SD). The clearance was 105 +/- 17 ml/kg/h and the apparent volume of distribution 1.1 +/- 0.2 L/kg assuming complete bioavailability. There was no indication of dose-dependent elimination of CBZ-E. The recovery of trans-CBZ-diol in urine collected for 3 days was 67 +/- 9% of the given dose. This enteric-coated formulation may thus in the future be used for the evaluation of the clinical effects of CBZ-E in patients.

Adult↗
PubMed1987

Effects of antidepressant treatments on platelet tritiated imipramine binding in major depressive disorder.

The effects of four antidepressant treatments on platelet tritiated imipramine binding have been studied in 51 hospitalized patients with severe major depressive disorder. There was an increase in maximum binding (Bmax) during the first week of treatment with antidepressants and electroconvulsive therapy, which was further magnified after three weeks' treatment with the serotonin uptake blockers alaproclate and zimeldine hydrochloride, but the Bmax values returned to baseline levels with nortriptyline hydrochloride and electroconvulsive therapy. The equilibrium dissociation affinity constant (Kd) did not change with any of the treatments. On reexamination one or two years after admission to the study, Bmax had not reached control values in clinically recovered, drug-free patients. Low pretreatment Bmax was associated with delusions during illness and with a poor long-term clinical outcome. There was no correlation between binding parameters and monoamine metabolite concentrations in the cerebrospinal fluid, either before or during treatment.

Adult↗
PubMed1987

Serotonin uptake inhibition during treatment of depression with nortriptyline caused by parent drug and not by 10-hydroxymetabolites.

Treatment of endogenous depression with nortriptyline (NT), at a daily dose of 150 mg, resulted in a pronounced improvement of seven of ten patients investigated. The concentration of the norepinephrine metabolite HMPG in cerebrospinal fluid (CSF) decreased by 29% (P less than 0.01) after 3 weeks of treatment. There was no significant effect of treatment on the serotonin and dopamine metabolites 5-HIAA and HVA. In previous larger materials, however, a decrease of 5-HIAA in CSF has been demonstrated. Platelets from the patients showed an increase in Km for serotonin uptake in response to NT treatment. The IC50 value of NT for serotonin uptake inhibition was 940 nM, while the corresponding value of the major metabolite of NT, i.e. E-10-OH-NT, was much higher (6700 nM). Thus, during treatment, the parent drug and not the metabolite was responsible for the serotonin uptake inhibition in platelets. There was a close correlation between Km and the plasma concentration of NT after 1 week of treatment (r = 0.88, P less than 0.01) but not after 3 weeks of treatment (r = 0.48; ns). There was no uniform effect of NT treatment on Vmax. It is concluded that clinical NT treatment results in uptake inhibition not only in norepinephrine but also in serotonin neurons.

Adult↗