Core Competencies in Clinical Neuropsychology as a Training Model in Europe

The multitude of training models and curricula for the specialty of clinical neuropsychology around the world has led to organized activities to develop a framework of core competencies to ensure sufficient expertise among entry-level professionals in the field. The Standing Committee on Clinical Neuropsychology of the European Federation of Psychologists’ Associations is currently working toward developing a specialty certification in clinical neuropsychology to establish a cross-national standard against which to measure levels of equivalency and uniformity in competence and service provision among professionals in the field. Through structured interviews with experts from 28 European countries, we explored potential areas of core competency. Specifically, questions pertained to the perceived importance of a series of foundational, functional, and other competencies, as well as current training standards and practices, and optimal standards. Our findings revealed considerable agreement (about three quarters and above) on academic and clinical training, despite varied actual training requirements currently, with fewer respondents relegating importance to training in teaching, supervision, and research (a little over half), and even fewer to skills related to management, administration, and advocacy (fewer than half). European expert clinical neuropsychologists were in agreement with previous studies (including those conducted in the United States, Australia, and other countries) regarding the importance of sound theoretical and clinical training but management, administrative, and advocacy skills were not central to their perspective of a competent specialist in clinical neuropsychology. Establishing a specialty certificate in clinical neuropsychology based on core competencies may enable mobility of clinical neuropsychologists across Europe, and, perhaps, provide an impetus for countries with limited criteria to reconsider their training requirements and harmonize their standards with others.

Clinical Neuropsychology as a Specialist Profession in European Health Care: Developing a Benchmark for Training Standards and Competencies Using the Europsy Model?

The prevalence and negative impact of brain disorders are increasing. Clinical Neuropsychology is a specialty dedicated to understanding brain-behavior relationships, applying such knowledge to the assessment of cognitive, affective, and behavioral functioning associated with brain disorders, and designing and implementing effective treatments. The need for services goes beyond neurological diseases and has increased in areas of neurodevelopmental and psychiatric conditions, among others. In Europe, a great deal of variability exists in the education and training of Clinical Neuropsychologists. Training models include master’s programs, continuing education courses, doctoral programs, and/or post-doctoral specialization depending on the country, with no common framework of requirements, although patients’ needs demand equal competencies across Europe. In the past 5 years, the Standing Committee on Clinical Neuropsychology of the European Federation of Psychologists’ Association has conducted a series of surveys and interviews with experts in the field representing 30 European countries. The information, along with information from the existing literature, is used in presenting an overview of current and relevant topics related to policy and guidelines in the training and competencies in Clinical Neuropsychology. An option for the way forward is the EuroPsy Specialist Certificate, which is currently offered in Work and Organizational Psychology, and in psychotherapy. It builds upon the basic certificate and complements national standards without overriding them. General principles can be found that can set the basis for a common, solid, and comprehensive specialty education/training, sharpening the Neuropsychologists’ competencies across Europe. The requirements in Clinical Neuropsychology should be comparable to those for the existing specialty areas in the EuroPsy model. Despite the perceived challenges, developing a specialist certificate appears a step forward for the development of Clinical Neuropsychology. Recommendations are proposed toward a shared framework of competencies by the means of a common level of education/training for the professionals in Europe. Benchmarking training standards and competencies across Europe has the potential of providing protection against unqualified and ethically questionable practice, creating transparency, raising the general European standard, and promoting mobility of both Clinical Neuropsychologists and patients in Europe, for the benefit of the professional field and the population.

Education, training, and practice among nordic neuropsychologists. Results from a professional practices survey

OBJECTIVE

To investigate sociodemographic characteristics, clinical and academic training, work setting and salary, clinical activities, and salary and job satisfaction among practicing neuropsychologists in four Nordic countries.

METHODS

890 neuropsychologists from Denmark, Finland, Norway, and Sweden participated in an internet-based survey between December 2013 and June 2015.

RESULTS

Three-fourths (76%) of the participants were women, with a mean age of 47 years (range 24-79). In the total sample, 11% earned a PhD and 42% were approved as specialists in neuropsychology (equivalent to board certification in the U.S.). Approximately 72% worked full-time, and only 1% were unemployed. Of the participants, 66% worked in a hospital setting, and 93% had conducted neuropsychological assessments during the last year. Attention deficit hyperactivity disorder, learning disability, and intellectual disability were the most common conditions seen by neuropsychologists. A mean income of 53,277 Euros was found. Neuropsychologists expressed greater job satisfaction than income satisfaction. Significant differences were found between the Nordic countries. Finnish neuropsychologists were younger and worked more hours every week. Fewer Swedish neuropsychologists had obtained specialist approval and fewer worked full-time in neuropsychology positions. Danish and Norwegian neuropsychologists earned more money than their Nordic colleagues.

CONCLUSION

This is the first professional practice survey of Nordic neuropsychologists to provide information about sociodemographic characteristics and work setting factors. Despite the well-established guidelines for academic and clinical education, there are relevant differences between the Nordic countries. The results of the study offer guidance for refining the development of organized and highly functioning neuropsychological specialty practices in Nordic countries.

Affect School for chronic benign pain patients showed improved alexithymia assessments with TAS-20

BACKGROUND

Alexithymia is a disturbance associated with psychosomatic disorders, pain syndromes, and a variety of psychiatric disorders. The Affect School (AS) based on Tomkins Affect Theory is a therapy focusing on innate affects and their physiological expressions, feelings, emotions and scripts. In this pilot study we tried the AS-intervention method in patients with chronic benign pain.

METHODS

The AS-intervention, with 8 weekly group sessions and 10 individual sessions, was offered to 59 patients with chronic non-malignant pain at a pain rehabilitation clinic in Sweden 2004-2005. Pre and post intervention assessments were done with the Hospital Anxiety and Depression scale (HAD), the Toronto Alexithymia Scale-20 (TAS-20), the Visual Analogue Scale for pain assessment (VAS-pain), the European Quality of Life health barometer (EQoL) and the Stress and Crisis Inventory-93 (SCI-93). After the group sessions we used Bergdahl's Questionnaire for assessing changes in interpersonal relations, general well-being and evaluation of AS.

RESULTS

The AS intervention was completed by 54 out of 59 (92%) patients. Significant reductions in total TAS-20 post-test scores (p = 0.0006) as well as TAS-20 DIF and DDF factors (Difficulties Identifying Feelings, and Difficulties Describing Feelings) were seen (p = 0.0001, and p = 0.0008) while the EOT factor (Externally Oriented Thinking) did not change. Improvements of HAD-depression scores (p = 0.04), EQoL (p = 0.02) and self-assessed changes in relations to others (p < 0.001) were also seen. After Bonferroni Correction for Multiple Analyses the TAS-20 test score reduction was still significant as well as Bergdahl's test after group sessions. The HAD, EQoL, SCI-93, and VAS-pain scores were not significantly changed. The AS-intervention was ranked high by the participants.

CONCLUSIONS

This pilot study involving 59 patients with chronic benign pain indicates that the alexithymia DIF and DDF, as well as depression, social relations and quality of life may be improved by the Affect School therapeutic intervention.

Studies on drug interactions between esomeprazole, amoxicillin and clarithromycin in healthy subjects

OBJECTIVE

A combination of esomeprazole, amoxicillin and clarithromycin may be used for Helicobacter pylori eradication. We explored the potential for interactions between these drugs.

METHODS

In 2 randomized, 4-way crossover studies, healthy CYP2C19 extensive metabolizers (EMs) received esomeprazole 40 mg once daily (n = 20) or 20 mg twice daily (b.i.d.) (n = 20), clarithromycin 500 mg b.i.d., amoxicillin 1 g b.i.d. or the combination of the 3 drugs for 7 days. In a third randomized, 2-way, crossover study, 6 healthy CYP2C 19 poor metabolizers (PMs) received esomeprazole 40 mg once daily with and without clarithromycin 500 mg b.i.d. for 1 week.

RESULTS

Triple therapy with esomeprazole 40 mg increased the area under the plasma concentration-time curve during the dosing interval (AUCtau) from 13.31 micromol x h/l (11.12-15.93) for esomeprazole alone to 22.69 micromol x h/l (18.94-27.17) for triple treatment. Respective AUCtau values with esomeprazole 20 mg b.i.d. were 4.97 micromol.h/l (3.97-6.21) and 11.29 micromol x h/l (9.03-14.12). Clarithromycin and amoxicillin plasma levels were largely unchanged by combination therapy. In PMs, the esomeprazole AUC also approximately doubled when administered in combination with clarithromycin. All treatments were well tolerated.

CONCLUSION

Clarithromycin decreases the metabolism rate of esomeprazole, leading to approximately doubled AUC values, both in EMs and PMs.

Unusual effects of separation conditions on chiral separations

Unusual effects in liquid chromatographic separations of enantiomers on chiral stationary phases are reviewed with emphasis on polysaccharide phases. On protein phases and Pirkle phases reversal of the elution order between enantiomers due to variation of temperature and mobile phase composition has been reported. Most of the nonanticipated observations have dealt with the widely used polysaccharide phases. Reversed retention order and other stereoselective effects have been observed by variation of temperature, organic modifier and water content in nonpolar organic mobile phases.

Direct chiral separation of almokalant on Chiralcel OD and Chiralpak AD for liquid chromatographic assay of biological samples

The four isomers of almokalant, a new antiarrhythmic substance under investigation, were separated by liquid chromatography on a Chiralcel OD and a Chiralpak AD column containing cellulose and amylose tris(3,5-dimethylphenylcarbamate), respectively. Both chiral stationary phases separate almokalant into the four isomers, but the retention orders are different if the carbamate is derivatized on cellulose or amylose. The Chiralcel OD column was used for the separation and determination of the isomers in urine at levels down to 100 nmol/l for the first three eluted and 200 nmol/l for the last with a relative standard deviation of less than 15%. The fluorescence response was increased by post-column ionization after stereoselective separation on the Chiralpak AD column. The isomers of almokalant could be determined at levels down to 10 nmol/l in plasma with a relative standard deviation of less than 15%.

Liquid chromatographic separation of the enantiomers of metoprolol and its alpha-hydroxy metabolite on Chiralcel OD for determination in plasma and urine

The two enantiomers of metoprolol and the four enantiomeric forms of alpha-hydroxymetoprolol were separated by liquid chromatography on a Chiralcel OD column containing a cellulose tris(3,5-dimethyl-phenylcarbamate) chiral stationary phase. The column efficiency was strongly dependent on the flow-rate and the enantioselectivity was influenced by temperature. Of utmost importance for the chiral separation was the water content of the mobile organic phase. The separation system was used for the separation and determination of the enantiomers in plasma and urine samples. The metoprolol enantiomers could be determined by fluorescence down to 10 nmol/l of each in plasma with a relative standard deviation of less than 15%.

Chromatography of calcium channel blockers

Numerous publications during the past ten years have described the determination of various calcium channel blockers in biological fluids, using gas and liquid chromatographic techniques. Diltiazem, verapamil, flunarizine and a growing number of dihydropyridines belong to this group of drugs, which in most instances are active at low plasma concentrations. From a bioanalytical point of view these compounds have many features in common, such as high lipophilicity and favourable detection properties.

Determination of urinary vanillylmandelic acid by direct injection and coupled-column chromatography with electrochemical detection

An automated column-switching system for determination of vanillylmandelic acid in urine is described. The liquid chromatographic system was composed of two separation columns with different selectivity properties, an octadecyl column coated with tributyl phosphate as stationary liquid phase and a silica-based anion exchanger. Urine samples were injected directly onto the first column, where vanillylmandelic acid was separated from the main part of the sample matrix. The internal standard isovanillylmandelic acid was co-eluting with vanillylmandelic acid, and a fraction of the eluate containing both substances was switched to the second column, where separation was performed. To assess peak purity, detection was performed with dual working electrodes in parallel mode. A relative standard deviation of 3.5% was obtained for determination of human urine samples containing 3 microM vanillylmandelic acid, and less than 0.1 microM could be detected.

Enantioselective determination of metoprolol in plasma by liquid chromatography on a silica-bonded alpha 1-acid glycoprotein column

The enantiomers of metoprolol were determined in plasma samples after direct resolution on a silica bonded alpha 1-acid glycoprotein column. Metoprolol was extracted from plasma into a diethyl ether-dichloromethane mixture and after back extraction to dilute phosphoric acid and adjustment of pH the sample was injected on a Chiral-AGP column for separation of R- and S-metoprolol. It was possible to measure down to 2 nmol per litre plasma with a relative standard deviation of less than 15% by use of gradient elution and fluorescence detection. The analytical method was employed to study the pharmacokinetics of the metoprolol enantiomers after administration of the racemate to humans.

Determination of 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in plasma by direct injection in coupled-column liquid chromatography with electrochemical detection

A method is described that allows determination of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in platelet-poor human blood plasma after direct injection of 50-100 microliters of plasma into a coupled-column liquid chromatographic system. The chromatographic system comprised an enrichment column and two separation columns with different selectivity properties. The samples were injected into the C18 enrichment column, which was eluted with a buffer solution as the mobile phase. 5-HT, 5-HIAA and the internal standard 5-hydroxy-N-methyl-tryptamine (5-HMT) were then desorbed by a stronger mobile phase and flushed into a cation exchanger, which separated 5-HT and 5-HMT. 5-HIAA passed straight through and was switched to a C18 column where it was retarded. After 5-HT and 5-HMT had been eluted from the cation exchanger and detected, the eluate from the C18 column was directed to the detector and 5-HIAA was determined. Basic plasma levels, about 4 nM for 5-HT and 30 nM for 5-HIAA, were measured with a relative standard deviation of about 5%.

Determination of metoprolol and two major metabolites in plasma and urine by column liquid chromatography and fluorometric detection

Metoprolol and its alpha-hydroxy metabolite were determined in plasma down to 2 nmol/l (S.D. 10-15%) after solvent extraction and bonded-phase liquid chromatography with fluorometric detection. The major metabolite with a carboxylic function was also measured in plasma when liquid-solid extraction on a column activated with dodecyl sulphate was applied. In urine the three components were assayed by direct injection of a diluted sample.

Liquid chromatographic method for the determination of 3,4-dihydroxyphenylethylene glycol and 3,4-dihydroxymandelic acid in plasma

A method is described for the simultaneous determination of the deaminated catecholamine metabolites 3,4-dihydroxyphenylethylene glycol (DOPEG) and 3,4-dihydroxymandelic acid (DOMA) in plasma by liquid chromatography with amperometric detection. The compounds are extracted from plasma by adsorption on alumina, then separated on a reversed-phase column coated with tributyl phosphate as the stationary liquid phase. It is a simple and selective method that permits the determination of basal levels of DOPEG and DOMA in plasma with a relative standard deviation of 3%.

Fully automated gradient elution liquid chromatographic assay of omeprazole and two metabolites

An automated liquid chromatographic method for the determination of omeprazole and two metabolites in plasma and urine is described. It utilizes the Technicon Fully-Automated-Sample-Treatment-LC system (FAST(R)-LC). Sample preparation is achieved by air-segmented continuous-flow providing solvent extraction, evaporation to dryness and reconstitution before injection onto a reversed-phase column. The compounds are separated by isocratic or gradient elution with acetonitrile-phosphate buffer mobile phases and quantified by UV-measurements at 302 nm. The limit of determination (relative standard deviation 10-15%) is 50 nmol l(-1) in plasma (800 microl) and 200 nmol l(-1) in urine (200 microl). The sample capacity is six or three samples per hour, depending on the elution mode.

Drug level monitoring: cardiovascular drugs

Methods for the determination of cardiovascular drugs in blood and plasma are critically reviewed with emphasis on gas and liquid chromatographic techniques. The importance of the various procedures is discussed, in particular sample work-up where the conditions for isolation and derivatization of the compounds are decisive for the accuracy and precision of the methods. Compared with other assay techniques chromatographic methods are generally to be preferred owing to their better selectivity. In the review the following groups are discussed: digitalis glycosides, antiarrhythmic agents, beta-adrenoceptor antagonists, vasodilating agents, antihypertensive compounds, and diuretics.

Determination of omeprazole and metabolites in plasma and urine

Omeprazole and three of its metabolites, the sulfone (H 168/66), the sulfide (H 168/22) and the hydroxy metabolite (H 195/80), are determined in plasma and urine by liquid chromatographic methods. The compounds are extracted from the biological sample and the extract is subjected to liquid chromatographic separation, either directly or after evaporation of the organic solvent and dissolution in a polar phase. The effluent from the column is UV-monitored at 302 nm and the quantitative evaluation performed by electronic integrator. Both a method with manual sample work-up and automatic injection and a fully automated system, Technicon FAST-LC, have been employed for the analyses. More than 25 000 samples have been assayed so far by these two methods.

Determination of omeprazole and metabolites in plasma and urine by liquid chromatography

Omeprazole, a substituted benzimidazole and a new gastric acid inhibitor, has been determined in plasma and urine, together with three of its metabolites--the sulphide, the sulphone and the hydroxy compound. The methods comprise extraction from the biological materials with methylene chloride, followed either by direct injection of the extract onto a normal-phase liquid chromatography column or evaporation, dissolution and injection onto a reversed-phase system. The compounds were detected using ultraviolet spectrometry. The absolute recoveries obtained were mostly above 95%. The minimum determinable concentration for omeprazole was 20 nmol/l in plasma (relative standard deviation 10-15%) and 50 nmol/l in urine. The metabolites could also be determined at the same levels.

Determination of 3,4-dihydroxyphenylethylene glycol and 3,4-dihydroxyphenylacetic acid in blood plasma by liquid chromatography with amperometric detection

Liquid chromatography with amperometric detection was employed for the determination of the dihydroxycatecholamine metabolites, 3,4-dihydroxyphenylethylene glycol (DOPEG) and 3,4-dihydroxyphenylacetic acid (DOPAC) in plasma. The compounds were isolated from plasma by adsorption onto alumina, the elution from which was found to be strongly dependent on the acid used. Conditions for the separation on octadecyl-bonded silica were evaluated with particular reference to the influence of pH, ion-pairing anions and quaternary ammonium ions. Recoveries of ca 85% and relative standard deviations of about 3% were obtained for the assay of endogenous concentrations.

Determination of catecholamines in urine by ion-exchange liquid chromatography with electrochemical detection

A liquid chromatographic method for the determination of free urinary concentrations of epinephrine, norepinephrine and dopamine is presented. For urine samples, pre-purified by adsorption onto alumina, ion-exchange chromatography was, in terms of selectivity, found to be superior to the more widely used reversed-phase chromatography. The column eluates were monitored with an electrochemical detector utilizing a glassy carbon working electrode. The method allows determination of the concentrations in 0.5 ml of normal urine samples with a relative standard deviation below 2%.

Arrhythmogenic assessment of prenalterol in conscious dogs

Possible arrhythmogenic side-effects of the positive inotropic agent prenalterol were studied in conscious dogs, three to four days after coronary artery ligation. Prenalterol showed a propensity to cause arrhythmias in one out of eight dogs, thereby confirming published data from clinical studies.

Solvent extraction of tricyclic amines from blood plasma and liquid chromatographic determination

The extraction of seven tricyclic antidepressant amines from human plasma at different pH values was investigated for dichloromethane, diethyl ether and hexane--1-pentanol (95:5). The amines were extracted as bases and back-extracted to sulphuric acid, 0.10 mol/l, prior to the separation by bonded-phase liquid chromatography. Ether and hexane--1-pentanol (95:5) were most suitable, tertiary amines being best extracted at pH 8, and secondary amines at pH 10. Using ether, both while 15 min ws sufficient for hexane--1-pentanol (95:5). UV detection allowed concentrations down to 10 ng in 1 ml of plasma to be determined. Three ammonium ions--octylammonium, dimethylammonium, and trimethylammonium--were added as modifiers to the mobile phase containing acetonitrile in phosphoric acid, 0.10 mol/l. In the concentration interval 0.010--0.030 mol/l all of the amine modifiers gave on Polygosil C8 peak asymmetry factors of sufficiently low magnitude, while on Li-Chrosorb RP-18 this was so only for di- and trimethylammonium in a concentration of 0.030 mol/l.

Determination of catecholamines in rat heart tissue and plasma samples by liquid chromatography with electrochemical detection

Liquid chromatography with electrochemical detection is used for the determination of adrenaline, noradrenaline and dopamine in rat heart tissue, and the method has also been applied to the determination of basic levels of these compounds in blood plasma. The catecholamines are isolated from the biological sample by adsorption onto alumina and are then desorbed by elution with perchloric acid. The stability of the compounds during the different stages in the work-up process has been studied. A greatly simplified procedure for the preparation of alumina is presented. Both ion-pair reversed-phase and ion-exchange liquid chromatography have been used for the separation of the catecholamines. For plasma samples the method has been validated against radioenzymatic assay and the choice of method is discussed.

The effect of antacid, metoclopramide, and propantheline on the bioavailability of metoprolol and atenolol

Concomitant administration of antacid increased the maximum concentration (Cpmax) and the area under the plasma concentration-time curve (AUC) of 100 mg oral dose of metoprolol by 25 per cent (p less than 0.05) and 11 per cent (p less than 0.1) respectively. For atenolol the opposite effect was observed and Cpmax and AUC were decreased by 37 and 33 per cent respectively (p less than 0.02). In both cases the antacid did not affect the time-course of atenolol in the plasma or its bioavailability. Propantheline prolonged the absorption phase of atenolol and the time of peaking (tmax) was shifted from 2.1 to 4.5 h. Cpmax of atenolol was essentially unchanged by propantheline pretreatment while the AUC was increased by 36 per cent. It is concluded that the negative effect of the antacid on the bioavailability of atenolol is caused by a reduction in the in vivo dissolution rate due to increased gastric pH. The positive effect of propantheline might be due either to more efficient absorption of atenolol in the upper part of the intestine or more extensive dissolution of the drug as a result of prolonged contact with gastric juice or a combination of these factors.

Plasma concentrations and beta-blocking effects in normal volunteers after intravenous doses of metoprolol and propranolol

The pharmacokinetics of metoprolol and propranolol in 6 healthy volunteers were compared after an intravenous dose of 10 mg of each drug. The mean t1/2, beta was 3.6 hr for both drugs, but due to a larger volume of distribution, the total body clearance was significantly higher for metoprolol (1.20 liters/min) than for propranolol (0.81 liters/min). The individual pharmacokinetic data were used to calculate the doses required to increase the amount of each drug in the body to 10 and 20 mg at 90 and 180 min respectively after an initial intravenous dose of 5.0 mg. The effect on exercise heart rate was determined 30 min after each dose. After identical doses, the two drugs had similar beta-blocking effects in terms of reducing exercise-induced tachycardia. These effects increased with the dose administered. The plasma levels of propranolol were twice as high as those of metoprolol for identical degrees of beta-blockade. The slope of the regression line for the relationship between the beta-blocking effect and log plasma concentrations was the same for the two drugs.

Determination of apomorphine in plasma and brain tissue by ion-pair extraction and liquid chromatography

Apomorphine is extracted from plasma or tissue homogenate with ethyl acetate. After back-extraction into hydrochloric acid, the apomorphine is extracted as an ion pair with 3,5-di-tert.-butyl-2-hydroxybenzene sulphonate into a small volume of methylene chloride and the solution is injected into the chromatographic column. Apomorphine is separated on microporous silica with a mixture of aqueous perchloric acid, methanol and methylene chloride as the mobile phase. With absorbance measurement of the eluent at 254 nm the method permits the determination of 15 pmol of apomorphine in 1 ml of plasma or in a rat brain. The coefficient of variation was 4% at the 100 pmol level.

Bioavailability and disposition of metoprolol and hydrochlorothiazide combined in one tablet and of separate doses of hydrochlorothiazide

1. The plasma levels and the urinary excretion of hydrochlorothiazide (HCT) have been studied after administration of single doses of 12.5 and 25 mg of the drug in solution and in combination with 100 mg of the selective beta 1-adrenoreceptor antagonist metoprolol in a rapidly dissolving tablet. 2. Metoprolol did not significantly influence the bioavailability or the time-course of HCT. 3. HCT had no significant effect on the time-course or the plasma levels of metoprolol. The average half-life, 4.4 +/- 0.9 h, is about the same as previously observed for separate doses of this drug. 4. It seems unlikely that repeated doses of the combination product studied will lead to biopharmaceutic or pharmacokinetic interactions of clinical importance.

Liquid chromatography in the monitoring of plasma levels of antiarrhythmic drugs

High-performance liquid chromatography has been employed in the development of assay methods for six antiarrhythmic drugs, disopyramide, lidocain, tocainide, procainamide, aprinidine and quinidine. Liquid-solid chromatography has been used and separation times of about 5 min have usually been sufficient. Owing to the capacity of the liquid chromatographic system, sample preparation has been minimized to a single extraction and direct injection of a considerable part of the extract. The overall time of analysis is very short and the methods are well suited for monitoring of plasma levels of the antirrhythmic drugs and in some instances (procainamide and disopyramide) also for their main metabolites. UV detection at the optimal wavelength has permitted determinations down to 50 pmole (20 ng) in 1 ml of plasma for the amines with high absorbance.

A selective method for determination of methylguanidine in biological fluids. Its application in normal subjects and uremic patients

A selective analytical method for the determination of methylguanidine in plasma in biological fluids has been developed. Methylguanidine is extracted in a column to dichloromethane as an ion pair with hexanitrodiphenylamine (dipicrylamine). It is isolated from coextracted compounds by partition chromatography as the picrate ion-pair. The methylguanidine fraction is collected and after reextraction to a buffer solution the methylguanidine content is quantitatively determined photometrically as picrate. An absolute recovery of 95 +/- 5% was obtained in the concentration range 1.5-10 microgram/ml plasma. The concentration of methylguanidine in plasma was higher in uremic patients, (44.4 +/- 5.71 mumol/l in conservatively-treated and 42.4 +/- 7.87 mumol/l in dialysis-treated patients) than in normal subjects, (4.0 mumol/l), but still lower than reported by other investigators using non-specific methods and also lower than the concentrations found to be toxic in experimental animals. There was a significant correlation between methylguanidine and creatinine concentration but no correlation between methylguanidine and urea concentration in plasma. No obvious relation was found between plasma methylguanidine concentration and various uremic symptoms, mode of treatment or protein intake.

Bioanalysis of picomole amounts of acetylcholine by ion-pair partition chromatography applied to rat sciatic nerve

A method for determination of acetylcholine in small, discrete biological objects by use of ion-pair technique has been developed. Acetylcholine is extracted as an ion pair with 3,5-di-t-butyl-2-hydroxybenzenesulphonate and separated from co-extracted components by ion-pair partition chromatography with picrate as the counter ion and porous cellulose as support. The quantitative evaluation is made from the acetylcholine peak in the chromatogram obtained by ultraviolet detection. Acetylcholine has been analysed in 1 cm large pieces of rat sciatic nerve containing about 60 pmol (10 ng). The overall recovery of the method is 100 +/- 10% at the 120 pmol level of acetylcholine in a sample.

Ion-pair partition chromatography in the analysis of drugs and biogenic substances in plasma and urine

Liquid-liquid chromatography based on the ion-pair partition technique gives separation systems of high efficiency when silica micro-particles are used as the support for the stationary phase. With 10-mum particles, plate heights of the order of 40-70 mum have been achieved with a linear velocity of 0.25 cm/sec. The retention in ion-pair partition systems is determined by the nature and concentration of the counter ion, and the properties of the mobile phase also have a major influence. It is often possible to predict the selectivity, and this can be controlled by varying the composition of the mobile phase. This paper describes the application of ion-pair partition chromatography to the bioanalysis of drugs, drug metabolites and biogenic substances. Typical counter ions in the stationary phase were methanesulphonate and perchlorate for ammonium compounds and tetrabutylammonium for the separation of organic anions. Determinations by liquid chromatography were demonstrated for quinidine and dihydroquinidine, metanephrine and normetanephrine and for imipramine and its demethyl metabolite in plasma. A quaternary ammonium compound, QX-572, was determined in urine and chromatograms are shown for the isolation of indoleacetic and hydroxyindoleacetic acid in urine. The methods have been used in routine analysis. Ultraviolet detection has permitted the determination of highly absorbing compounds down to the 10-ng level in plasma and urine.

Micromethod for the determination of bupivacaine in maternal and foetal blood during obstetric analgesia

A method for the determination of bupivacaine in maternal and foetal blood during obstetric analgesia is described. The drug and the internal standard, 1-pentyl-2-(2,6-xylylcarbamoyl)-piperidine, are initially extracted into methylene chloride. Perchloric acid is added to retain bupivacaine and the standard as Perchlorates in the organic phase accomplishing a selective separation from less hydrophobic amines. Bupivacaine and the standard are then re-extracted into sulphuric acid, followed by a purification with methylene chloride. The aqueous extract is finally made alkaline and the compounds extracted into 10 μl methylene chloride. This extract is analysed by gas chromatography using a 3% OV-17 column. The standard deviation of the method at therapeutic concentrations is about 10% and the lowest level which can be determined with reasonable accuracy is 15 ng ml−1.