Is computer-assisted aminoglycoside dosing managed by a pharmacist a safety tool of pharmacotherapy?

This pilot prospective study verified the hypothesis that use of computer-assisted therapeutic drug monitoring of aminoglycosides by pharmacists leads to better safety therapeutic outcomes and cost avoidance than only concentration measurement and dose adjustments based on a physician's experience. Two groups of patients were enrolled according to the technique of monitoring. Patients (Group 1, n=52) underwent monitoring by a pharmacist using pharmacokinetic software. In a control group (Group 2, n=11), plasma levels were measured but not interpreted by the pharmacist, only by physicians. No statistically significant differences were found between the groups in factors influenced by therapy. However, the results are not statistically significant but a comparison of the groups showed a clear trend towards safety and cost avoidance, thus supporting therapeutic drug monitoring. Safety limits were achieved in 76 % and 63 % of cases in Groups 1 and 2, respectively. More patients achieved both concentrations (peak and trough) with falling eGFR in Group 1. In present pilot study, the pharmacist improved the care of patients on aminoglycoside therapy. A larger study is needed to demonstrate statistically significantly improved safety and cost avoidance of aminoglycoside therapy monitoring by the pharmacist using pharmacokinetic software.

Analysis and management of drug related problems on a nephrology ward from a pharmacist's point of view.

The main goal of the study was to determine the incidence and the character of drug related problems (DRPs) identified in chronic kidney disease patients by the clinical pharmacist at the nephrology department. As secondary objective, the aim was to identify the frequency and character of DRPs of selected high risk drugs in medication reviews. The clinical pharmacist reviewed patients' medication records and made drug therapy-related recommendations to physicians. The clinical pharmacists' interventions were categorized using an adaptation of the Pharmaceutical Care Network Europe. During the study period (January 2016 - June 2018) the clinical pharmacist performed 1192 interventions in 1870 adult patients admitted to the Nephrology Department. The most frequent DRP was untreated indication 324 (27.18%) of all interventions, and incorrect dose 248 (20.81%). Anti-infectives were identified as the drug category with the highest frequency of interventions. Almost 93% of all interventions were accepted by the attending physicians. Still within the second objectives, underdosing was observed as the most frequent problem for renally excreted drugs. It was found that an incorrect dose is a very frequent issue at the nephrology department. Surprisingly, the main problem was underdosing. In the category of renally excreted drugs, underdosing was observed in antithrombotics and antivirals. The above- mentioned results prove the need of a clinical pharmacist, preferably in sense of maximizing of the treatment effect and improving the care of patients.

Stereoselective interactions of warfarin enantiomers with the pregnane X nuclear receptor in gene regulation of major drug-metabolizing cytochrome P450 enzymes.

BACKGROUND: Warfarin, an antagonist of vitamin K, is an oral coumarin anticoagulant widely used to control and prevent thromboembolic disorders. Warfarin is clinically available as a racemic mixture of R- and S-warfarin. The S-enantiomer has three to five times greater anticoagulation potency than its optical congener. Recently, vitamin K2 function has been proposed via the pregnane X receptor (PXR) in osteocytes. PXR acts as a xenobiotic sensor that controls expression of many genes involved in drug/xenobiotic metabolic clearance. OBJECTIVE: The aim was to examine whether enantiomers of warfarin stereoselectively interact with PXR to up-regulate main drug/xenobiotic-metabolizing enzymes of the cytochrome P450 superfamily. METHODS: Interactions of warfarin enantiomers with PXR were tested by gene reporter assays and time-resolved fluorescence resonance energy transfer technology (TR-FRET) ligand binding assay. Up-regulation of PXR-target gene mRNAs by warfarin enantiomers was studied using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) in primary human hepatocytes. RESULTS: We found that R-warfarin interacts with the PXR nuclear receptor. Consistently, R-warfarin significantly induced CYP3A4 and CYP2C9 mRNAs in cultures of primary human hepatocytes or in LS174T intestinal cells. On the other hand, S-warfarin is a less potent inducer of PXR-target genes in human hepatocytes and activates PXR only at supraphysiological concentrations. In addition, we showed that racemic 10- and 4'-hydroxywarfarins are also highly potent PXR ligands and inducers of CYP3A4 and CYP2C9 mRNA in human hepatocytes. CONCLUSION: We showed that R-warfarin can significantly up-regulate major drug-metabolizing enzymes CYP3A4 and CYP2C9 in the liver and thus may cause drug-drug interactions (DDI) with co-administered drugs. The results warrant reconsideration of racemic warfarin usage in clinics.

An evidence for regulatory cross-talk between aryl hydrocarbon receptor and glucocorticoid receptor in HepG2 cells.

Aryl hydrocarbon receptor (AhR) and glucocorticoid receptor (GR) play crucial role in the regulation of drug metabolizing enzymes and in many essential physiological processes. Cellular signaling by these receptors shares several functional and regulatory features. Here we investigated regulatory cross-talk between these two receptors. Human hepatoma cells (HepG2) were the model of choice. We analyzed the effects of dexamethasone (DEX) and dioxin (TCDD) on i) expression of AhR and GRalpha mRNAs; ii) levels of AhR and GR proteins; iii) transcriptional activities of AhR and GR in reporter assays; iv) 7-ethoxyresorufin-O-deethylase activity (EROD). We found that both DEX and TCDD affected AhR and GR mRNAs expression, proteins levels and transcriptional activities in HepG2 cells. These effects on cellular signaling by AhR and GR comprised up-/down-regulation of gene expression and ligand-dependent protein degradation. We conclude that interactive regulatory cross-talk between GR and AhR receptors in HepG2 cells defines possible implications in physiology and drug metabolism. Future research should be focused on the investigation of AhR-GR cross-talk in various normal human cells and tissues both in vitro and in vivo.

Evaluation of novel microtubules interfering agents myoseverin, tubulyzine and E2GG in primary cultures of rat hepatocytes.

We investigated the effects of novel microtubules interfering agents (MIAs) in primary cultures of rat hepatocytes. Cells were treated for 24 h with a known compound colchicine and newly synthesized derivatives myoseverin, tubulyzine, and E2GG. We examined the effects of MIAs on microtubules network integrity and on the polymerization capability of isolated tubulin. All tested MIAs inhibited microtubules assembly with the following IC(50) values: tubulyzine (4.4 + or - 0.9 micromol/l), myoseverin (7.0 + or - 0.8 micromol/l), E2GG (16 + or - 2 micromol/l), colchicine (2.0 + or - 0.4 micromol/l). The potency of MIAs to perturb microtubular network integrity (monitored by immune-histochemistry) increased in the order tubulyzine < myoseverin < E2GG < colchicine. We described recently deleterious effects of MIAs on the expression of drug metabolizing enzymes, including CYP1A1. Here we observed inhibitory effects of novel MIAs on dioxin-inducible expression of CYP1A1 mRNA in rat hepatocytes. We conclude that novel MIAs exert analogical biological response as classical MIAs such as colchicine or nocodazole. This further supports the hypothesis that tubulin is the primordial target of MIAs within the cell and that perturbation of microtubules dynamics and/or integrity triggers the biological effects described here.

Examination of Glucocorticoid receptor alpha-mediated transcriptional regulation of P-glycoprotein, CYP3A4, and CYP2C9 genes in placental trophoblast cell lines.

The placental trophoblast at different stages of pregnancy contains some drug transporters and xenobiotic-metabolising enzymes, as well as ligand-activated nuclear receptors, which control their inducible transcriptional regulation. Glucocorticoid receptor alpha (GRalpha) is expressed in both placental syncytiotrophoblast and cytotrophoblast. GRalpha was shown to control inducible expression of several enzymes of the cytochrome P-450 family (CYP) and the drug transporter P-glycoprotein in the liver. However, GRalpha-mediated transcriptional regulation of drug transporters and CYPs has not been studied in the placental trophoblast. In this study, we examined the expression and activity of GRalpha in the transcriptional regulation of P-glycoprotein, CYP3A4, and CYP2C9 in placental trophoblast cell lines. Employing RT-PCR, Western blotting, and luciferase gene reporter assay, we detected the expression and activity of GRalpha in JEG3 and BeWo cell lines. However, we observed that only MDR1 mRNA was up-regulated after treatment of placental cells with dexamethasone. Accordingly, only the promoter of the MDR1 gene was activated by dexamethasone in gene reporter assays in placental cells and the activation was abolished by RU486, an antagonist of GRalpha. CYP3A4 and CYP2C9 promoters were activated in placental cells only after co-transfection with hepatocyte nuclear factor 4alpha (HNF4alpha), which indicates the hepatocyte-specific character of GRalpha-mediated regulation of the genes. On the other hand, coexpression of HNF4alpha had no effect on the activation of the MDR1 gene promoter, suggesting HNF4alpha-independent regulation via GRalpha. We conclude that GRalpha may be involved in the transcriptional regulation of P-glycoprotein in the placental trophoblast. We also indicate that the CYP3A4 and CYP2C9 genes are not inducible through GRalpha in placental cell lines, due to the lack of HNF4alpha expression and possibly some additional hepatocyte-specific transcriptional factors.

Corticosterone transfer and metabolism in the dually perfused rat placenta: effect of 11beta-hydroxysteroid dehydrogenase type 2.

Although rat is the most widely used model of glucocorticoid programming of the fetus, the role of rat placental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) in the transplacental pharmacokinetics of the naturally occurring glucocorticoid, corticosterone, has not yet been fully elucidated. In this study, expression of 11beta-HSD2 in the rat placenta on two different gestation days (16 and 22) was examined using quantitative RT-PCR and Western blotting, and dually perfused rat term placenta was employed to evaluate its functional capacity to transfer and metabolize corticosterone. Marked decrease in placental expression of 11beta-HSD2 toward term was observed on both mRNA and protein levels. In perfusion studies, increasing maternal corticosterone concentration from 3 to 200 nM resulted in the fall of 11beta-HSD2 conversion capacity from 64.3 to 16.3%, respectively. Enzyme saturation occurred at about 50 nM substrate concentration. When delivering corticosterone (3 or 100 nM) from the fetal side, a similar decline of 11beta-HSD2 conversion capacity was observed (66.5% and 48.5%, respectively). Addition of carbenoxolone (10 or 100 microM), a non-specific 11beta-HSD inhibitor, to maternal perfusate decreased conversion capacity from 66.7 to 12.6 or 8.1%, respectively. Similarly potent inhibitory effect was observed in feto-maternal studies. Neither saturation nor inhibition of 11beta-HSD2 was associated with transformation of corticosterone in metabolites other than 11-dehydrocorticosterone. These data suggest that 11beta-HSD2 is the principal enzyme controlling transplacental passage of corticosterone in rats and is able to eliminate corticosterone in both maternal and fetal circulations.

[Physiologic function of P-glycoprotein]. / Fyziologická funkce P-glykoproteinu.

P-glykoprotein has been proposed to function as a membrane transport protein for a large variety of substrates, ranging from small lipophilic molecules, steroid hormones, lipophilic peptides, some drugs, biologically important molecules and xenobiotics. There is little doubt that P-glycoprotein transports a wide range of substrates out of cells, nevertheless it is difficult to explain its wide substrate specificity and mechanism of the transport. P-glycoprotein has been found to be a major cause of acquired multidrug resistance (MDR) of cancer cells to chemotherapeutic drugs. The identification and localization of P-glycoprotein expression in a variety of normal human tissues raised the question of the physiological functions of P-glykoprotein. Currently, there is considerable evidence that P-glycoprotein can protect the body and sensitive tissues against a range of different xenobiotics. In addition, P-glycoprotein might play a role in regulation of cell differentiation, proliferation, immune response and programmed cell death.

Determination of rhodamine 123 by sequential injection technique for pharmacokinetic studies in the rat placenta.

The sequential injection (SIA) technique was applied in pharmacokinetic studies of the transporter-mediated passage of a model substrate, rhodamine 123 (Rho123), through the dually perfused rat term placenta. The method described was used for real-time monitoring of Rho123 concentrations in both the maternal and fetal compartments. Determination was processed by fluorescence detection (lambda(ex)=480 nm, lambda(em)580 nm); calibration curve was linear over the range 0.01-50 mumoll(-1) (r=0.99965), detection limit was 10 nmoll(-1) (3sigma) and RSD2% (10 readings). Transport of Rho123 was scanned under various conditions (ATP-synthesis inhibition) and several inhibitors of P-glycoprotein transporter were tested (e.g. quinidine). The advantages of the modern SIA method-an automated analytical tool providing both fast and precise analysis-were successfully demonstrated for examination of transport profiles to investigate the effect of P-glycoprotein on the placental transfer of Rho123.

Influence of P-glycoprotein on the transplacental passage of cyclosporine.

The transfer kinetics of cyclosporine across the dually perfused rat placenta in the maternal to fetal direction and a possible involvement of P-glycoprotein were investigated. The transplacental clearance of cyclosporine in the materno-fetal direction was found to be dependent on the maternal inflow concentration of cyclosporine. Coadministration of cyclosporine with an excess of quinidine or chlorpromazine into the maternal compartment revealed 1.7- and 1.9-fold increase in cyclosporine concentration in the fetal compartment. In the experiments where quinidine was present both in the maternal and fetal compartments, cyclosporine appeared in the fetal compartment significantly faster, and its amount was three times higher when compared with controls. Conversely, quinidine or chlorpromazine did not affect the transplacental passage of L-[(3)H]-glucose. The interference of quinidine with the metabolism of cyclosporine in the placenta was excluded because only traces of M-1 and M-17 metabolites were found in the fetal solutions. Sodium azide, a mitochondrial respiratory inhibitor, was found to double the rate of cyclosporine, but not L-[(3)H]-glucose, passage across the placenta. Our findings indicate that P-glycoprotein pumps cyclosporine out of the trophoblast cells of the rat placenta in the ATP-dependent manner and restricts the passage of cyclosporine across the placental barrier.

Stereoselective pharmacokinetics of flobufen in rats.

Stereoselectivity of the pharmacokinetics of the nonsteroidal anti-inflammatory drug flobufen, 4-(2', 4'-difluorobiphenyl-4-yl)-2-methyl-4-oxobutanoic acid, was studied in male Wistar rats after intravenous administration. Pharmacokinetic parameters and chiral inversion of flobufen enantiomers were studied after a bolus injection of the racemate and individual enantiomers (5 mg/kg). Determinations of the enantiomers in rat plasma were performed using chiral HPLC (terguride column). After i.v. administration of flobufen racemate, plasma levels of R-enantiomer decreased more rapidly. The S-/R-enantiomer ratio of AUCs after rac-flobufen was 13.3. The total plasma clearance value of S-flobufen was more than 10-fold lower than R-flobufen. The other pharmacokinetic parameters of the enantiomers were also significantly different. While only traces of R-enantiomer (less than 1%) were detected in rat plasma after S-flobufen administration, considerable conversion to the S-enantiomer was found after injection of R-flobufen (R-enantiomer AUC/S-enantiomer AUC = 0.52). The results indicate substantial stereoselectivity in the disposition of flobufen enantiomers in the rat, which is, at least in part, attributed to chiral bioconversion.

Unidirectional transfer of D-xylose across the rat placenta.

1. The transplacental transfer of D-xylose was investigated in the present study. 2. Umbilical perfusion of the rat term placenta was used to study materno-foetal (M-F) and foetomaternal (F-M) transfer of this compound. 3. D-Xylose was found to cross the rat term placenta very quickly in the M-F direction, with subsequent accumulation in the foetal compartment (the F-M ratio being 2.23 at the end of the experiments). In contrast, no transfer in the F-M direction was observed. 4. A possible facilitation of the transplacental transfer of D-xylose from the mother to foetus in rats is suggested.

[Echocardiographic and hemodynamic studies on the influence of verapamil in hypertrophic obstructive cardiomyopathy (author's transl)]. / Echokardiographische und hämodynamische Untersuchungen zur Beeinflussung der hypertrophischen obstruktiven Kardiomyopathie druch Verapamil.

15 patients with obstructive hypertrophic cardiomyopathy were studied by m-mode echocardiography and 9 of them also by left heart catheterism before and after 10 mg Verpamil. The following results were obtained: 1. The systolic anterior movement (SAM) of the mitral valve was reduced (p less than 0.005), 2. the enddiastolic and endsystolic diameter were increased (p less than 0.02 and 0.05 respectively), 3. the EF-slope remained unchanged. 4. The left ventricular systolic pressure was reduced (p less than 0.025) and the gradient diminished from an average value of 58 to 34 mmHg (p less than 0.02), 5. heart rate and left ventricular enddiastolic pressure remained constant. The results of this acute study suggest a beneficial effect of Verpamil in patients with hypertrophic obstructive cardiomyopathy.

[Preliminary hemodynamic studies on the activity of meproscillarin (author's transl)]. / Orientierende hämodynamische Untersuchungen über die Wirksamkeit von Meproscillarin.

In 10 patients with arterial hypertension and left heart failure the hemodynamic effect of 14-hydroxy-3-beta-[4-O-methyl-alpha-L-rhamnopyranosyl)oxy]-14beta-bufa-4,20,22-trienolide (Ky 18, meproscillarin, Clift) was compared with placebo in a double-blind study. 15 min after oral administration of meproscillarin there was an increase of cardiac output and stroke volume by up to 25%. Heart rate, arterial blood pressure and left ventricular filling pressure remained unchanged.

[The serum triglycerides and their role as a coronary risk factor (author's transl)]. / Die Rolle der Serumtriglyceride als koronarer Risikofaktor.

291 patients with various types of hyperlipoproteinemia and 216 persons with normal serum lipid levels were examined for the frequency of angina pectoris and myocardial infarction. As a risk factor of myocardial infarction, Fredrickson's Type IIb was ranking on top, followed by simultaneous elevation of serum cholesterol and serum triglycerides regardless of the lipid-electrophoretic tappern, followed by Fredrickson's Type IV and finally by isolated hypercholesterolemia and Fredrickson's Type IIa. For angina pectoris, the order was slightly different: the highest risk factor was the simultaneous elevation of serum cholesterol and serum triglycerides, followed by hyperlipoproteinemia Type IV, hyperlipoproteinemia Type IIb, and finally by isolated hypercholesterolemia. The risk of both myocardial infarction and angina pectoris caused by isolated hypertriglycerolemia was not statistically significant, the same observation was made for the risk of angina pectoris in hyperlipoproteinemia Tye IIa. The present results confirm that an elevation of the serum triglycerides plays a minor role as a coronary risk factor in comparison to hypercholesterolemia.

[Exercise echocardiography in coronary heart disease (author's transl)]. / Belastungsechokardiographie bei koronarer Herzkrankheit

23 patients with coronary heart disease (11 with angiographically normal and 12 with depressed left ventricular function) were studied by m-mode echocardiography before and after handgrip. The following results were obtained: 1. There were statistical significant differences in enddiastolic volume, ejection fraction, and circumferential fiber shortening between the two groups. 2. Isometric exercise (handgrip) did not alter left ventricular dimensions or contractility, if mean values were calculated in both groups. 3. The majority of patients with compromised left ventricular function at rest, however, responded to handgrip by increasing their enddiastolic volume, apparently using the diastolic volume reserves. Ejection fraction and circumferential fiber shortening remained constant. 4. The majority of patients with angiographically normal left ventricular function at rest, on the contrary, displayed augmented contractility under handgrip. Only 4 out of 11 patients with proximally located, high-degree lesions and inadequate collaterals responed to isometric exercise with a reduction of ejection fraction and circumferential fiber shortening.

[Cardiac pacing in tachycardiac arrhythmias]. / Schrittmachertherapie tachykarder Herzrhythmusstörungen.

Cardiac pacing may be useful in the management of supraventricular and ventricular tachycardias. Prophylactically, recurrent ectopic tachycardias may be prevented by atrial or ventricular pacing for a sustained period at a rate faster than the spontaneous rate, but slower than the rate of the tachycardia being suppressed. Moreover, the pacemaker permits the dosage of antiarrhythmic agents to be increased until the recurrent arrhythmias are completely controlled. Therapeutically, supraventricular tachycardias may be terminated by (1) overdrive suppression, (2) delivery of a single stimulus or two serial stimuli or repetitive stimulation at a rate slower than the tachycardia (competitive stimulation) and (3) orthorhythmic stimulation. Today, implantable units exist. Advantages and disadvantages as well as risks of pacing in patients with tachycardias, are discussed.

[Mitral valve function during frequency stimulation in coronary disease. Echocardiographic and hemodynamic comparative studies]. / Mitralklappenfunktion unter Frequenzstimulation bei koronarer Herzerkrankung. Echokardiographie und hämodynamische Vergleichsuntersuchungen

In 3 controls and 10 patients with coronary heart disease (CHD) and angina pectoris (AP) left ventricular enddiastolic pressure (LVEDP) and pulmonary artery diastolic pressure (PADP) are measured at rest (R) and during right atrial pacing with stepwise increments in heart rate. The values were compared to the simultaneously recorded DE-slope and EF-slope of the mitral valve echocardiogram. The following results could be obtained: 1. In the control group PADP increased sharply at a rate of aobut 120/min, while LVEDP further decreased. This "physiological dysfunction" of the mitral valve could not be detected by echocardiography. 2. In patients with CHD and AP both pressures rose concomitantly with the onset of the angina; moreover, the EF-slope showed a significant reduction. 3. This decrease of the EF-slope is due to an increment of LVEDP during angina and may be used as a diastolic tool, if the exercise electrocardiogram is negative. 4. LVEDP and EF-slope are correlated weil in most patients with CHD. However, there was a lack of correlation between the reduction of the EF-slope and left ventricular function.