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.

[Metamizol--a new effective analgesic with a long history. Overview of its pharmacology and clinical use]. / Metamizol--nové úcinné analgetikum s dlouhou historií. Prehled farmakologie a praktického vyuzití.

Metamizol is an effective, non-opioid analgesics which was originally introduced to the therapy in the year 1922. However, with the reference to the side effects of other related pyrazolone derivatives its administration, similarly as the usage of other pyrazolones, was significantly limited. Later, metamizol has been used, usually mixed, with spasmolytic agents and quite recently it has been introduced as a mono-component medicament. Metamizol proved to be a very effective analgesic. When administered in equipotent doses, it had its effects comparable to various opioid analgesics, such as tramadol, pentazocine and pethidine. Beside the strong analgesic effect, it produces also significant antipyretic and splasmolytic effects without the adverse, unpleasant anticholinergic impact. Its spasmolytic effect on the smooth muscle of the sphincter Oddi, urinary tract, and the gal bladder is comparable to the effects of buthylscopolamine. Unlike aspirin and other nonsteroidal antiinflammatory drugs it has, however, no antiinflammatory activity when administered in clinical doses. Similarly, metamizol has no effect on the CNS, cardiovascular system, renal and metabolic functions. On the other hand, metamizol, like aspirin, has got a significant effect on the aggregation of platelets. Metamizol is basically a prodrug. The parent substance is not effective before its conversion into two active metabolites (4-methylaninoantipyrine and 4-aminoantipyrine) in the body. Metamizol is well absorbed from the small intestine but only two above mentioned active metabolites and no parent drug can be detected in the blood. The active metabolites are consequently metabolised to ineffective metabolites including the relevant acetylderivatives, in which the acetylation phenotypes can be distinguished. In the therapy, metamizol can be used, as an analgesic, at post-surgical pain, patient's controlled analgesia (PCA), at the cancer's pain and in the pains of different origin (post-traumatic pain, the pain at myocardial infarction, craniocerebral trauma, and the invasive diagnostic interventions), as well as at he pain of neuromuscular origin, headache and migraine. Its spasmolytic effect in connection with a strong analgesic activity is very useful at various colic attacks. Further, metamizol is a useful antipyretic both in the adults and children. Its adverse effects are not pronounced and drug interactions are minimal. Only when metamizol is administered together with cyclosporine, the blood levels of the last substance should be regularly checked.

[Effective and safe pharmacotherapy of acne vulgaris and treatment of sun-damaged skin]. / Ucinná a bezpecná farmakoterapie acne vulgaris a lécba solárního poskození kuze.

An inevitable condition for the pharmacist is a basic knowledge of dermatological changes which are prominent in acne and solar impairment of the skin to be able to recommend in a qualified manner an effective and safe treatment to the patient. However, sufferers of the more serious forms of acne should always be referred to their general practitioner, or preferentially a dermatologist. Acne vulgaris is an androgen-induced disorder, but three major mechanisms for the development of the disease have been identified: hypertrophy of the sebaceous gland, hyperkatosis of the follicular epithelium, and proliferation of microbial flora, particularly Propionibacterium acnes. The basis of all lesions is the microcomedone which is developed into the ripe comedone. Inflammatory lesions are thought to be due to proliferation of P. acnes. In the selfmedication of common acne, benzoyl peroxide, which in a 5-10% lotion exerts antimicrobial and keratolytic properties, proved to be useful. Patients appreciate a lot its instant effect which is visible after just one day of treatment. Salicylic acid is another effective drug, which, when used on the long-term basis, has comedolytic properties; it reduces the number of microcomedones and counteracts plugging of the follicles. In addition, in healthy young women who take oral contraception, a triphasic combined oral preparations of contraceptives with newer progestins, notably with norgestimmate, which is practically free of androgenic effects, are recommended with advantage for the treatment of moderate acne vulgaris without any adverse effects. Solar impairment of the skin, the so-called solar ageing, is clinically indistinguishable from biological ageing. Changes connected with solar impairment appear mostly in the dermis, where solar elastosis develops, the skin gets drier and wrinkle formation appears. For the treatment, hydroxy acids are recommended, namely salicylic acid, which is very effective, because in combination with a suitable vehicle it produces desquamation or exfoliation. Desquamation is beneficial as it gives a youthful appearance to the skin.

[Common gastrointestinal symptoms and their effective and safe treatment]. / Nekteré bezné gastrointestinální symptomy a jejich úcinná a bezpecná lécba.

The pharmacist is an important specialist in the selection of the drug when the patient comes for pharmacist's advice of how to alleviate common gastrointestinal symptoms. Of all drugs which can be effective in these situations, only three drugs (bismuth subsalicylate, psyllium, and docusate sodium) proved to be advantageous for self-medication. Bismuth subsalicylate (BSS) is much appreciated in the treatment of peptic ulcers where it not only covers the base of the ulcer but also eradicates Helicobacter pylori. Therefore this drug does not treat only the symptoms but the cause of the disease as well. Dyspepsia may also be effectively treated with BSS because of its strong and rapid protective effect on the gastric mucosa. Last but not least, the salicylate component of this substance and not bismuth alone is responsible for the elimination of diarrhoea in the so-called traveller's diarrhoea, as the salicylate decreases enhanced secretion of fluid in the colon. On the other hand, the natural fibre psyllium may effectively alleviate constipation, because it increases the volume and weight of stools as well as the transit time in the colon and facilitates defecation. Similarly, docusate sodium is a detergent agent which facilitates the entrance of water into the stool, which is then better and more easily pushed out from the large intestine.

[Self-medication of the common cold]. / Samoterapie symptomu nemoci z nachlazení.

Self-medication can be useful in the multisymptomatic management of the common cold and other preferentially non-febrile flu-like symptoms, especially as at present multicomponent remedies are available, which may make self-medication significantly easier with consequent better compliance of adult patients. Children, on the contrary, are not suitable acceptants of self-medication mediated by their parents because the sickness exhibits in children nearly exclusively febrile progress. The procedure of the therapy to be really effective and safe must be necessarily concentrated into pharmacies, where safety and efficacy of therapy are ensured by the pharmacist as the last link of contact between the patient and the drug. Any other distribution of the OTC drugs is therefore strictly unacceptable. Patients suffering from the common cold usually exhibit simultaneously various symptoms of the disease. These different symptoms are, however, experienced during the day with different intensity. During the day and often also in the course of the labour process there is a need to concentrate on the most bothersome symptoms, notably the relief of the nasal congestion with the exploration of the safest and most effective drug, such as pseudoephedrine. In addition, it is necessary to administer an effective nonsteroidal anti-inflammatory drug, preferably ibuprofen, which provides relief from symptoms caused by release of inflammatory mediators. In the night time there is a need of a multisymptom therapy which may relieve cough and any other disturbing cold symptoms to allow satisfactory beneficial, continuous, and refreshing sleep.

Pharmacokinetic examination of antipyrine passage through the placenta and the small intestine in rats.

The placental and small intestinal barriers, though obviously different, show many functional as well as morphological similarities. When the surface area of both barriers in man was recalculated to a unit of body weight, nearly identical values (2.71 and 2.86 m2/kg of body mass, respectively) were obtained. The aims of the present study were (1) to compare mutual permeability of these two barriers to antipyrine (AP), and (2) to describe pharmacokinetics of AP in pregnant and non-pregnant rats. In placental studies AP showed that its rapid transfer through the placenta (k(tr) = 0.046 min(-1)) was governed by the mechanism of passive diffusion. In the closed circuit, FMCR(eq) was 1.085, t(eq) was 112.10 min and k(eq) was 0.020 min(-1). Absorptive studies performed on the rat small intestine indicated an identical mechanism of drug transport. The apparent first-order absorption rate constant of AP was 0.479 min(-1), and Tmax was 8.95 minutes. Differences in AP pharmacokinetics between pregnant and non-pregnant rats were significant during the distribution phase (t(1/2) = 3.78 and 5.87 min, respectively), whereas the elimination phase was unaffected. AP has been demonstrated, as expected, to be an excellent marker for drug transport studies through different body barriers.

Different transfers of N-acetyl-p-aminobenzoic acid and p-aminobenzoic acid across the placenta and the small intestine in rats.

The aim of the present study was to evaluate the transfer of N-acetyl-p-aminobenzoic acid (AcPABA) across the rat term placenta and the rat small intestine and to compare it with that of its parent drug p-aminobenzoic acid (PABA). Umbilical perfusion of the rat term placenta was used to determine the materno-fetal transfer. AcPABA appeared in the fetal compartment significantly more slowly than PABA (k transfer = 0.023 and 0.064 min(-1), respectively). The rate of equilibration between the maternal and fetal compartments was slightly lower for AcPABA than for the parent drug (k eqilibration = 0.0082 and 0.011 min(-1), respectively). Similarly, AcPABA was shown to be absorbed from the small intestine significantly more slowly than PABA (ka = 0.052 and 0.82 min(-); tmax = 37 and 3.1 min, respectively). Our results showed that both investigated compounds which are structurally related and very similar in their physical-chemical characteristics crossed both the placental and small intestinal barrier with a different kinetics. AcPABA was transported across both barriers significantly more slowly than its parent compound, which might indicate a possible equipment of the placenta with a carrier for PABA, a similar one to that previously found in the rat small intestine.

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.

Phenytoin transfer across the in situ perfused rat term placenta.

Transfer of phenytoin (PHT) across the rat term placenta perfused in situ was investigated and compared with that of antipyrine (AP) as a marker of passive diffusion. PHT was shown to cross the placenta with similar kinetics as AP did. Both the first order transfer constant (ktr = 0.070 min-1) and the first order equilibration constant (keq = 0.027 min-1) of PHT were comparable to those of AP (ktr = 0.046 min-1, keq = 0.022 min-1). Similarly, there were significant differences between PHT and AP in the foeto-maternal concentration ratio at equilibrium (FMCReq = 1.01 and 1.09, respectively). The present data indicate that the transfer of PHT through the rat placenta is governed by the same principles as that of AP, i.e. by the mechanism of passive diffusion. Surprisingly, maternal plasma protein binding of PHT (60.5%) did not seem to influence either its rate of transfer or its eventual foeto-maternal concentration ratio.

Pharmacokinetic examination of p-aminobenzoic acid passage through the placenta and the small intestine in rats.

In the present study the permeability of the rat small intestine and the placenta to p-aminobenzoic acid (PABA) and antipyrine (AP) was investigated. Perfusion of the rat term placenta was used to determine the materno-fetal transfer of both compounds. PABA appeared in the fetal compartment faster than AP (ktransfer = 0.064 and 0.046 min-1, respectively). The rate of equilibration between the maternal and fetal compartments and placental clearance were lower for PABA than for AP (kequilibration = 0.011 and 0.020 min-1; Clp = 0.22 and 0.33 ml/min, respectively); the feto-maternal concentration ratios at equilibrium (FMCReq) were, however, mutually comparable. Similarly, PABA proved to be absorbed from the small intestine significantly faster than AP (ka = 0.824 min-1 and 0.479 min-1; tmax = 3.1 min and 8.9 min, respectively). The apparent volume of distribution (Vd) of AP in non-pregnant animals showed that the drug is distributed into the whole body water as expected (Vd = 0.66 l/kg); however, Vd of AP in pregnant animals was estimated to be 1.81 l/kg. Vd of PABA in non-pregnant animals showed its partially limited distribution, which was only slightly increased in the pregnant animals. Our results confirmed a faster penetration of hydrophilic PABA across the placenta and the small intestine than that of lipophilic AP. The mechanism of transplacental passage of PABA, however, remains to be determined.

Mechanisms of action of some air pollutants on the airways.

Common air pollutants (O3, SO2) exert their deleterious effects in several ways, mostly on the respiratory functions. Ozone causes formation of peroxides and aldehydes with subsequent release of inflammatory lipids and cytokines. Changes in the activity of neutral endopeptidase and release of neuropeptides may occur. As a result, bronchial hyperreactivity can be detected. In the mechanisms of the disturbances due to sulfur dioxide, cholinergic mechanisms and release of neuropeptides may be involved.

Analysis of pharmacotherapy of hypertension in out-patients.

In the present pilot study an attempt was made to evaluate the usefulness of results obtained about the treatment of patients suffering from high blood pressure for a pharmacoepidemiological study of the therapeutic value of antihypertensive agents. Data from 90 hypertensive patients were used in the present retrospective-prospective study. These patients all attended an out-patient clinic located in one of the East-Bohemian districts that are participating in the MONICA programme. Instead of the analysis of the population data, regular blood pressure measurements, plasma glucose levels, and total cholesterol concentrations were measured and analysed. The consumption of various antihypertensive drugs in this study was similar to that found in larger studies performed in other health districts of the Czech Republic. Diuretics were the drugs most frequently prescribed for hypertensive patients. General practitioners rarely prescribed calcium channel blockers and angiotensin-converting enzyme inhibitors in 1990 and 1991. The metabolic effects of antihypertensive drugs, mostly diuretics, were not significantly evident. The most frequent occurrence of non-compensated blood pressure was recorded for the treatments with Trimecryton and methyldopa. However, the validity of these findings should be tested in a larger group of hypertensic patients.

Pharmacokinetic parameters of verapamil and its active metabolite norverapamil in patients with hepatopathy.

Verapamil (CAS 52-53-9) is a calcium channel blocker with a vasodilatatory effect. Because of its significant first-pass effect, verapamil might be advantageous in the treatment of portal hypertension. It does not produce any excessive systemic effects, provided the doses are suitably adjusted. A decision was made to examine the pharmacokinetic parameters, independent of compartmental analysis of verapamil and its active metabolite norverapamil, in patients with portal hypertension. Their biological half-lives of the terminal phase were significantly prolonged as compared with the control group. However, no statistically significant differences were found in the values of tmax and Cmax. The calculated pharmacokinetic parameters of norverapamil were not significantly different from those of verapamil, except for the tmax of norverapamil, which was significantly longer in patients suffering from portal hypertension as compared with verapamil. The ratio of areas under the plasma concentration-time curve (AUC) of verapamil and norverapamil was comparable in both groups of patients. No relationship between the changes in the pharmacokinetic parameters and the extent of hepatic insufficiency was observed.

Intestinal absorption of tolfenamic acid at experimental malabsorption states in rats.

Absorption kinetics of 14C-labelled N-(3-chloro-o-tolyl)-anthranilic acid (tolfenamic acid, 14C-TA, Clotam) from the small intestine was studied in intact rats and in rats with malabsorption states provoked by methotrexate, starvation, and triparanol. 14C-TA was administered intravenously and intraduodenally, and the drug concentrations in the blood were followed up radiometrically. A multi-compartmental model was applied for mathematical analysis. Theoretical model parameters were computed, and absorption parameters were then derived from the theoretical ones. The absorption half-life of 14C-TA was 5.3 min in the controls, 10.8 min in the methotrexate-intoxicated, 7.5 min in the fasted, and 5.3 min in the triparanol-intoxicated rats. The absorbed fraction of the intraduodenal 14C-TA dose was 100% in each experimental group as well as in the controls. It is suggested that the slower transfer of 14C-TA through the intestinal barrier in the methotrexate-intoxicated and fasted rats may be caused by the reduction of the absorptive surface.