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Biomedical subjects

E M Hawes

Publications and source records attributed to E M Hawes.

At least 73 records · Page 4Linked to original sources
PubMed1988

Radioimmunoassay for fluphenazine sulfoxide in human plasma.

Antisera to fluphenazine sulfoxide were raised in New Zealand white rabbits to an immunogen synthesized by covalent linkage of bovine serum albumin to 10-[[3-[4-(4-carboxybutyl)-1-piperazinyl] propyl]]-2-trifluoromethyl-10H-phenothiazine 5-sulfoxide. With use of an antiserum, a radioimmunoassay for fluphenazine sulfoxide was developed that is able to quantitate 0.156 ng ml-1 using only a 200 microliter plasma sample with a coefficient of variation less than 5%. The antiserum had negligible cross-reactivities to fluphenazine (less than 1%) and its important metabolites, such as fluphenazine N4'-oxide (1%), 7-hydroxyfluphenazine (less than 1%), and N4'-deshydroxy-ethylfluphenazine (1%). The cross-reactivities with structurally similar phenothiazine 5-sulfoxides, such as those of trifluoperazine, prochlorperazine, perphenazine, and N4'-deshydroxyethylfluphenazine, were considerable, such that the antiserum can be used to develop a quantitative radioimmunoassay for any of these compounds. The reported radioimmunoassay was found to be suitable and adequate to quantitate fluphenazine sulfoxide in the plasma of patients treated with oral or intramuscular fluphenazine.

Fluphenazine↗
PubMed1988

An ultrasensitive method for the measurement of haloperidol and reduced haloperidol in plasma by high-performance liquid chromatography with coulometric detection.

A new analytical method has been developed for the simultaneous quantitation of haloperidol and reduced haloperidol in plasma. The method is based on high performance liquid chromatography (HPLC) with coulometric detection. The extraction and sample clean up procedures are simple and rapid to execute, yet yield chromatograms virtually free of interference from endogenous plasma constituents, such that the extraordinary sensitivity of the coulometric detector can be exploited fully. The detection limits for haloperidol and reduced haloperidol are 20 pg/ml plasma, and the limits of quantitation are 50 pg/ml for both drug and metabolite. Standard curves were linear down to 50 pg/ml with coefficients of variation of less than 7.0% at the limits of quantitation. The method was applied to the study of the plasma levels of haloperidol and reduced haloperidol in two healthy subjects. It was possible to monitor the plasma levels of haloperidol for at least 96 h (4 days) after the administration of a 5-mg oral dose of haloperidol. It was also possible to monitor reduced haloperidol levels over 96 h in one subject, although the metabolite was not detectable in the plasma of the other at any stage.

Chromatography, High Pressure Liquid↗
PubMed1988

Development of a radioimmunoassay procedure for sulforidazine and its comparison with a high-performance liquid chromatographic method.

A radioimmunoassay (RIA) procedure for the determination of sulforidazine in human plasma was developed using an antiserum raised in rabbits immunized with N-(2-carboxyethyl)desmethylsulforidazine-porcine thyroglobulin conjugate. The RIA procedure can measure as low as 40 pg of sulforidazine in a 200-microliter human plasma sample with a coefficient of variation of less than 6%. The antiserum did not show any marked cross reaction with any available potential cross reactant. Also, there were no significant differences between the concentrations of sulforidazine determined in the presence or absence of thioridazine and/or mesoridazine. This RIA procedure was compared with a high performance liquid chromatographic (HPLC) method by determining concentrations of sulforidazine in plasma samples from human volunteers over 72 h after administration of single 50-mg oral doses of thioridazine hydrochloride. The two methods showed a good correlation for the assay values (n = 55; r2 = 0.926) and the slope of the regression line was not significantly different from 1.0 (p greater than 0.30 when RIA values were plotted on the gamma-axis and HPLC values on the chi-axis; p greater than 0.30 when HPLC values were plotted on the gamma-axis and RIA values on the chi-axis). The plot of the differences between these two assay values against the average of the assay values showed that the differences were independent of the concentration range studied. Also, statistically favorable comparisons were obtained for area under the plasma concentration-time curve to 48 h (AUC48(0)), Cmax, and Tmax calculated from the data obtained by the two methods.

Animals↗
PubMed1988

S-oxidation of thioridazine to psychoactive metabolites: an oral dose-proportionality study in healthy volunteers.

Thioridazine has two major active metabolites, which are formed from S-oxidation of its 2-methylthio group; the sulphoxide, mesoridazine, and the sulphone, sulforidazine. Dose proportionality of the three compounds was investigated for the first time in 11 males after administration of three single oral doses (25, 50, and 100 mg) of thioridazine hydrochloride separated in each case by two weeks. Based on the plasma concentrations of the three analytes over 72 h following each dose, large intersubject variabilities in such parameters as AUCot and Cmax were observed for each of the three compounds. The relationships between dose and parameters such as AUCot and Cmax for each analyte were described by an equation for a straight line (r2 greater than or equal to 0.8). However, the mean apparent distribution and elimination rate constants for thioridazine and mesoridazine and the mean apparent oral clearance for thioridazine decreased significantly with increasing dose, suggesting non-linearity in the elimination of thioridazine at high dose.

Adult↗
PubMed1988

The metabolism of chlorpromazine N-oxide in the rat.

1. The metabolism of chlorpromazine N-oxide was studied in female rats after a 20 mg/kg single oral dose. 2. Metabolites identified in both urine and faeces were chlorpromazine, 7-hydroxychlorpromazine, chlorpromazine sulphoxide, N-desmethylchlorpromazine and N-desmethylchlorpromazine sulphoxide. 3. Metabolites were separated by h.p.l.c. or g.l.c. prior to mass spectrometric analysis. The structures of the metabolites were confirmed by direct comparison of their mass spectra and chromatographic behaviours with those of authentic compounds. 4. Chlorpromazine N-oxide and any metabolite which retained the intact N-oxide function, such as chlorpromazine, N,S-dioxide, could not be identified in any of the extracts. 5. When 3H-chlorpromazine N-oxide was administered under the same conditions; approximately twice as much radioactivity was excreted in the faeces (52.1 +/- 9.7%) as in the urine (26.9 +/- 7.2%).

Administration, Oral↗
PubMed1987

Influence of urinary pH on the disposition of methoxyphenamine and three metabolites in humans.

The disposition of methoxyphenamine (o-methoxy-N,alpha-dimethylphenethylamine) and three of its metabolites was studied in five healthy volunteers on three occasions, with the urine pH separately under uncontrolled, acidic, and basic conditions. All five volunteers were extensive metabolizers of debrisoquine and methoxyphenamine, the latter with respect to O-demethylation and aromatic 5-hydroxylation. The plasma peak concentration and the area under the curve of methoxyphenamine from 0 to infinity did not differ significantly during the three phases of the study. However, on the average, its renal clearance increased by fivefold and its plasma terminal half-life decreased by twofold in the acidic as compared with the alkaline urine condition. The urinary excretions of methoxyphenamine and its metabolites N-desmethylmethoxyphenamine and O-desmethylmethoxyphenamine were significantly enhanced in the uncontrolled pH and the acidic urine conditions as compared with the alkaline urine condition. By contrast, the urinary excretion of the 5-hydroxymethoxyphenamine metabolite was not significantly affected by urinary pH variations. The mean urinary excretion ratios methoxyphenamine: O-desmethylmethoxyphenamine and N-desmethylmethoxyphenamine: O-desmethylmethoxyphenamine did not differ significantly during the three phases of the study, whereas the methoxyphenamine:5-hydroxymethoxyphenamine and N-desmethylmethoxyphenamine:5-hydroxymethoxyphenamine ratios were significantly altered during the alkaline phase as compared with the other two phases. Therefore, the ratios in terms of O-desmethylmethoxyphenamine are recommended for phenotyping individuals when using methoxyphenamine as a metabolic probe.

Adult↗
PubMed1987

The sulfoxidation of fluphenazine in schizophrenic patients maintained on fluphenazine decanoate.

Highly sensitive radioimmunoassays were applied to study the sulfoxidation of fluphenazine in 30 schizophrenic patients maintained on either 5 mg or 25 mg fluphenazine decanoate by intramuscular injection every 14 days over a period of 6 months. The presence of the sulfoxide metabolite was detected in all but one of the patients, such that 97% of the 340 plasma samples analysed contained the metabolite. Interpatient variations in plasma levels of fluphenazine, fluphenazine sulfoxide, and in drug to metabolite plasma level ratios were several fold higher than the corresponding intrapatient variations at both dosages. There were statistically significant tendencies for mean plasma fluphenazine levels to rise and mean plasma sulfoxide levels to fall over the 6-month period of study among patients on the high dose, consistent with our previously reported observation that it takes 3-6 months to establish a steady state of fluphenazine with this dosage regimen. By contrast, there were no statistically significant changes in mean plasma levels of either fluphenazine or its sulfoxide in patients on the low dose. Nevertheless, there was a significant rise in fluphenazine to fluphenazine sulfoxide mean plasma level ratios in both dosage groups. It is difficult to assess the significance of the changes in the drug to metabolite ratios with time, since there are no kinetic data on the phase II metabolism (conjugation) of fluphenazine or fluphenazine sulfoxide. This study shows that sulfoxidation is an important major pathway in the metabolism of intramuscularly-administered fluphenazine, and implies that metabolic sites other than gut wall are also involved in the process.

Fluphenazine↗
PubMed1987

Methoxyphenamine O-demethylase and 5-hydroxylase: a GLC-ECD assay to study their activities and their inhibition by debrisoquine and sparteine.

A GLC-ECD method is described for the determination of the O-desmethyl, N-desmethyl and aromatic 5-hydroxy metabolites of methoxyphenamine in liver homogenates. The O-desmethyl and 5-hydroxy metabolites are deficient in poor metabolizers of debrisoquine and sparteine and the Dark Agouti rat model of this human phenotype. The present analytical method can be useful in determining methoxyphenamine O-demethylase and 5-hydroxylase activities as well as identifying those substrates which inhibit these and are worthy of further study.

Animals↗
PubMed1987

Synthesis and properties of haptens for the development of radioimmunoassays for thioridazine, mesoridazine, and sulforidazine.

For the separate development of radioimmunoassay procedures for thioridazine and its two major active metabolites, mesoridazine and sulforidazine, three haptens, respectively, 2-methylthio-, 2-methylsulfinyl-, and 2-methylsulfonyl-substituted 10-[2-[1-(2-carboxyethyl)-2-piperidinyl]ethyl]-10H-phenothiazine, were synthesized and characterized. Thioridazine hapten was coupled to bovine serum albumin, whereas the haptens for mesoridazine and sulforidazine were coupled to porcine thyroglobulin. The number of hapten residues per mole of carrier protein was determined in each case by an ultraviolet spectrophotometric method. Polyclonal antibodies to each hapten-protein conjugate were obtained in rabbits, and titers of the antisera were checked by evaluating their binding characteristics to the appropriate tritiated analyte. A hapten for the ring sulfoxide metabolite of thioridazine was also synthesized.

Animals↗
PubMed1987

A new radioimmunoassay of thioridazine and its comparison with a high performance liquid chromatographic method and another radioimmunoassay.

A new radioimmunoassay (RIA) procedure for the determination of thioridazine in plasma is described. Antiserum was produced in rabbits immunized with N-(2-carboxyethyl)desmethylthioridazine-protein conjugate. The developed RIA procedure can measure as low as 80 pg of thioridazine in a 200-microliter human plasma sample with a coefficient of variation of less than 5%. This RIA procedure was compared with previously reported RIA and high performance liquid chromatographic (HPLC) methods by determining plasma concentrations of thioridazine in samples from human volunteers over 72 h after administration of single 50-mg oral doses of thioridazine hydrochloride. There was a good correlation between the assay values (n = 55) determined by the new RIA and HPLC methods (r2 = 0.916), and the slope of the regression line was not significantly different from 1.0 (p greater than 0.60, 95% confidence limits 0.981 +/- 0.081 when RIA values were plotted on the y axis, and HPLC values on the x axis; p greater than 0.10, 95% confidence limits 0.934 +/- 0.080 when HPLC values were plotted on the y axis and RIA values on the x axis). Also, the plot of the differences between these two assay values against the average of the assay values showed that the differences were independent of the concentration range studied. Similar favorable statistical comparisons were obtained when the assay values (n = 44) determined for thioridazine by the two RIA procedures were compared with one another.

Analysis of Variance↗
PubMed1987

Development of a radioimmunoassay procedure for mesoridazine and its comparison with a high-performance liquid chromatographic method.

A radioimmunoassay (RIA) procedure for mesoridazine was developed using an antiserum raised in rabbits immunized with N-(2-carboxyethyl) desmethylmesoridazine-porcine thyroglobulin conjugate. The RIA procedure enabled the quantitation of 40 pg of mesoridazine in a 200-microliters human plasma sample with a coefficient of variation of less than 5%. Except for N-desmethylmesoridazine, the antiserum showed no marked cross-reaction with any of the other available potential cross-reactants. Furthermore, statistically indistinguishable results were obtained for the determination of mesoridazine in the presence or absence of a fivefold excess of thioridazine or sulforidazine. This RIA procedure was compared with a high-performance liquid chromatographic (HPLC) method by determining concentrations of mesoridazine in plasma samples from human volunteers over 72 h after administration of single 50-mg oral doses of thioridazine hydrochloride. Good correlation existed between the assay values (n = 55) determined by the RIA and HPLC methods (r2 = 0.940), but the slope of the regression line was significantly different from 1.0 (p less than 0.05, when RIA values were plotted on the gamma axis and HPLC values were plotted on the chi axis; p less than 0.001, when HPLC values were plotted on the gamma axis and RIA values were plotted on the chi axis). The plot of the differences between these two assay values against the average of the assay values showed, however, that the differences were independent of the concentration range studied. Moreover, statistically favorable comparisons were obtained for area under the plasma level/time curve to 48 h (AUC0(48)), Cmax, and Tmax calculated from the data obtained by the two methods.

Animals↗
PubMed1987

Therapeutic monitoring of chlorpromazine. IV: Comparison of a new high-performance liquid chromatographic method with radioimmunoassays for parent drug and some of its major metabolites.

A new high-performance liquid chromatographic (HPLC) procedure for the simultaneous determination of chlorpromazine and its six metabolites, namely, 7-hydroxy-chlorpromazine, N-monodesmethyl-chlorpromazine, 7-hydroxy-N-monodesmethyl-chlorpromazine, chlorpromazine-sulfoxide, chlorpromazine N-oxide, and N-monodesmethyl-chlorpromazine-sulfoxide, in plasma was developed and compared with four radioimmunoassay (RIA) procedures that measured separately chlorpromazine, 7-hydroxy-chlorpromazine, chlorpromazine-sulfoxide, and chlorpromazine N-oxide. The results of this study for the determination of plasma levels in four healthy volunteers given a 100-mg single oral dose of chlorpromazine hydrochloride demonstrated that in some cases, strong correlations could be found between the plasma levels determined by the HPLC and RIA procedures, whereas in other cases, there was a lack of strong correlation. The discrepancies observed were not only due to nonspecificity of the immunoassay procedures employed, but also to a lack of rigorous specificity of the HPLC procedure in plasma samples from dosed humans. These findings clearly indicate that even a chemical method of analysis, such as HPLC, has its limitations in its application to multianalyte analysis, as is the case with drugs like chlorpromazine.

Chlorpromazine↗
PubMed1986

Fluphenazine plasma levels in patients receiving low and conventional doses of fluphenazine decanoate.

Plasma fluphenazine concentrations (FLU) were measured in 45 patients with schizophrenic disorders who participated in a double-blind comparison of 5 and 25 mg fluphenazine decanoate (FD). The rise in plasma level of FLU 24 h after a "test dose" was significantly correlated with steady state FLU concentration at 12 weeks (for 5 mg patients, r = 0.45, P = 0.04; for 25 mg, r = 0.78, P = 0.005). Patients who had low FLU at baseline required nearly 6 months to reach a steady state when they received 25 mg. Patients who received 5 mg and had low FLU at baseline continued to demonstrate relatively low plasma levels for the entire 1st year. Although the mean FLU at 6 months was lower for patients who relapsed during the subsequent 18 months (0.57 ng/ml for relapsers vs 1.01 ng/ml for nonrelapsers), this difference was not statistically significant. When plasma levels from both dosage groups were combined, FLU at 12 weeks correlated significantly with factor scores for akinesia (r = 0.52, P = 0.002) and BPRS cluster scores for retardation (r = 0.52, P = 0.002). These results indicate that the measurement of fluphenazine plasma levels may be useful in determining when patients treated with FD are receiving drug doses which are likely to cause discomforting side effects.

Adult↗
PubMed1986

Development and application of a specific radioimmunoassay for trifluoperazine N4'-oxide to a kinetic study in humans.

A hapten derivative of prochlorperazine N4'-oxide, 7-(3-carboxy-propionyl)-prochlorperazine N4'-oxide, was synthesized and coupled to bovine serum albumin. Immunization of New Zealand White rabbits with this conjugate generated antibodies which were utilized to develop a radioimmunoassay (RIA) for the quantitation of trifluoperazine N4'-oxide (TFPNO). This assay enabled for the first time the quantitation of TFPNO in plasma, and 20 pg can be measured in a 200-microliter plasma sample with a coefficient of variation less than 5%. Statistically, indistinguishable results were obtained by the assay procedure with or without the selective extraction of TFPNO, and also in the presence or absence of an excess of trifluoperazine (TFP) and other major metabolites, such as trifluoperazine sulfoxide and 7-hydroxytrifluoperazine. This RIA and a previously reported RIA for TFP were used to directly determine plasma concentrations of TFP and TFPNO after administration of a single 5-mg p.o. dose of TFP to six healthy male volunteers. The mean +/- S.D. for the peak concentration, time to peak concentration, area under the curve from 0 to 72 hr and the elimination T1/2 for the terminal portion of the plasma concentration vs. time curve for TFPNO were found to be 3.7 +/- 0.7 ng/ml, 3.2 +/- 0.4 hr, 51.1 +/- 9.8 ng X hr/ml and 26.9 +/- 14.0 hr, respectively, whereas the corresponding values for TFP were found to be 2.7 +/- 0.7, 3.1 +/- 0.8, 42.2 +/- 6.9 and 21.9 +/- 6.5, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Therapeutic monitoring of chlorpromazine. III: Minimal interconversion between chlorpromazine and metabolites in human blood.

Chlorpromazine (CPZ), chlorpromazine sulfoxide (CPZSO), and chlorpromazine N-oxide (CPZNO) were each incubated (37 degrees C), for various timed intervals up to 60 min, with pooled human whole blood. Plasma and red blood cells were then separated and analyzed by a high performance liquid chromatographic method that avoids the use of alkaline extraction procedures. It was found that CPZ, CPZSO, and CPZNO were remarkably stable in whole blood under physiological conditions. CPZ was converted into CPZSO to a small extent (1%). Reports of 15-50% conversion of CPZ into CPZSO are largely due to artifacts, which result when red blood cell materials come into contact with alkali. CPZNO was recovered (85%) unchanged from the plasma. A small portion (1%) of the CPZNO was reduced to CPZ in the red blood cells. Thus, on the basis of these in vitro data, blood does not appear to be an important tissue for the metabolism of CPZ, CPZSO, or CPZNO.

Biotransformation↗
PubMed1985

Radioimmunoassay for the 7-hydroxy metabolite of trifluoperazine and its application to a kinetic study in human volunteers.

A hapten derivative of the 7-hydroxy metabolite of trifluoperazine, 7-hydroxy-10-[[3-[4-(2-carboxyethyl)-1-piperazinyl]propyl]]-2 -tri-fluromethyl-10H-phenothiazine, was synthesized and coupled to bovine serum albumin. Immunization of New Zealand white rabbits with this drug-protein conjugate resulted in the production of antisera, one of which was subsequently utilized in the development of an RIA procedure. The described RIA for the first time enables the quantitation of the 7-hydroxy metabolite of trifluoperazine in human plasma after oral administration of single and therapeutic doses of trifluoperazine, in which 20 pg of the nonconjugated 7-hydroxy metabolite in 200 microL of plasma can be measured with a CV of less than 3% in B/Bo readings. Similar results were obtained by this assay procedure with or without the selective extraction of the 7-hydroxy metabolite and in the presence or absence of a large excess of trifluoperazine and other suspected major metabolites, such as the sulfoxide and N4'-oxide metabolites. This RIA procedure, together with a previously developed RIA for trifluoperazine, was used to directly determine plasma concentrations of trifluoperazine and its 7-hydroxy metabolite after administration of a single 5-mg oral dose of trifluoperazine to six healthy male volunteers. The mean +/- SD for the peak concentration (Cmax), the time to Cmax, the area under the curve from 0 to 24 h and, the apparent terminal elimination half-life for the 7-hydroxy metabolite were found to be 0.86 +/- 0.2 ng/mL, 6.2 +/- 1.6 h, 11.1 +/- 4.9 ng . h/mL, and 10.6 +/- 5.7 h, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗