Clinical aspects of reimbursement policies for orphan drugs in Central and Eastern European countries.

Objectives: The aim of this study was to characterize the reimbursement policy for orphan drugs (ODs) in Central and Eastern European (CEE) countries in relation to the availability and impact of clinical evidence, health technology assessment (HTA) procedure, selected economic indicators, and the drug type according to indications. Materials and methods: A list of authorized medicines with orphan designation and information about active substance, Anatomical Therapeutic Chemical (ATC) classification, and therapeutic area was extracted from the web-based register of the European Medicines Agency (EMA). A country-based questionnaire survey was performed between September 2021 and January 2022 in a group of selected experts from nine CEE countries (an invitation was sent to 11 countries). A descriptive and statistical analysis was conducted to determine statistical significance, correlations, between the drug or country characteristic and the positive recommendation or reimbursement of ODs. Results: The proportion of reimbursed orphan drugs differed between countries, ranging from 17.7% in Estonia to 49.6% in Hungary (p < 0.001). The odds that ODs were reimbursed were reduced in countries with a "strong" level of impact of drug safety and efficacy on reimbursement decisions (p=0.018), the presence of other additional specific clinical aspects (e.g., genomic data) considered in the reimbursement decision (p < 0.001) and mandatory (without exception) safety assessments (p=0.004). The probability that ODs were reimbursed was increased in countries with a "moderate" level of impact of drug safety and efficacy on reimbursement decisions (p=0.018), when reimbursement decisions are dependent on the EMA registration status and orphan drug designation (p < 0.001), the presence of the "positive HTA recommendation guarantees reimbursement" policy (p < 0.001), higher GDP per inhabitant (p=0.003), and higher healthcare expenditure (p < 0.001). Conclusion: We found that there are differences among CEE countries in the reimbursement of orphan drugs, and we identified aspects that may influence these differences. Safety, efficacy, and specific clinical aspect issues significantly influenced reimbursement decisions. Antineoplastic and immunomodulating agents drugs were the largest group of ODs and increased the chance of getting a positive recommendation. The higher GDP per inhabitant and healthcare expenditures per inhabitant were positively linked to the chance that an OD receives reimbursement.

Patient Access, Unmet Medical Need, Expected Benefits, and Concerns Related to the Utilisation of Biosimilars in Eastern European Countries: A Survey of Experts.

This policy research aims to map patient access barriers to biologic treatments, to explore how increased uptake of biosimilars may lower these hurdles and to identify factors limiting the increased utilisation of biosimilars. A policy survey was developed to review these questions in 10 Central and Eastern European (CEE) and Commonwealth of Independent States (CIS) countries. Two experts (one public and one private sector representative) from each country completed the survey. Questions were related to patient access, purchasing, clinical practice, and real-world data collection on both original biologics and biosimilars. Restrictions on the number of patients that can be treated and related waiting lists were reported as key patient access barriers. According to respondents, for both clinicians and payers the primary benefit of switching patients to biosimilars would be to treat more patients. However, concerns with therapeutic equivalence and fear of immunogenicity may reduce utilisation of biosimilars. Similar limitations in patient access to both original biologics and biosimilars raise concerns about the appropriateness and success of current biosimilar policies in CEE and CIS countries. The conceptual framework for additional real-world data collection exists in all countries which may provide a basis for future risk-management activities including vigorous pharmacovigilance data collection.

How General Practitioners and Their Patients Adhere to Osteoporosis Management: A Follow-Up Survey among Czech General Practitioners.

Introduction: General practitioners (GPs) are key participants in osteoporosis (OP) management. The aim was to evaluate their adherence to lege artis management of the disease, potential barriers, and to discuss differences observed in comparison with the baseline survey carried out in 2007; the focus was on secondary prevention. Methods: On behalf of two professional associations, 2-round postal survey among randomly selected GPs (>1/4 of all Czech GPs) was performed in 2014. The questionnaire covered areas concerning GP's role in the fight against OP, knowledge about OP, management of OP-related fractures, barriers to the management of OP, system- and patient-related in particular, and availability and use of information sources. Results: The overall questionnaire return rate was 37% (551 respondents); mean age of the respondents was 53 year (37% men). The GP's role in the treatment of OP was rated as essential in 28 and 37% of men and women, respectively (P = 0.012). The guideline for diagnosis and treatment of OP for GPs was considered accessible by 92% of respondents. As much as 60% of the respondents were adherent to the guideline, i.e., used it repeatedly. The knowledge of several risk factors was very good, however, recommended daily intake of calcium was stated correctly by only 41% of respondents, and daily intake of vitamin D by only 40%. Three quarters reported active steps after a fracture: referral to a specialist, life-style recommendations, prescription of calcium/vitamin D supplements. Half of the respondents focus on fall prevention. System-related barriers, such as lack of possibility to prescribe selected drugs (61%) and financial limits set by health insurance company (44%) were most frequently reported. Patient-related barriers were also common, patient's non-adherence (reported by 29%) and patient's reluctance to go to a specialist (18%). Conclusion: GPs adhered to OP management more than in 2007. Knowledge of risk factors and involvement in post-fracture care was relatively high. Compared to baseline survey, patient-related barriers, patient non-adherence in particular, were more common. Prescribing conditions are still an important issue. Among GPs, education should be focused on calcium and vitamin D intake, doses, sources, and supplements.

Patterns of Non-adherence to Supplementation with Calcium and Vitamin D in Persistent Postmenopausal Women Are Similar at Start and 1 Year Later: A Qualitative Longitudinal Study.

Background: Osteoporosis is a chronic disease and adherence can fluctuate over time. Therefore, longer observation is necessary to investigate the stability of patients' adherence. The study aim was to compare the overall adherence (OA) to supplementation with the fixed combination of calcium and vitamin D (Ca/D) in postmenopausal women at baseline and after 1 year, and to evaluate the fluctuation of the OA in individual months. Furthermore, we studied whether adherence is influenced by signing of informed consent and routine medical check-up. Methods: This was a longitudinal, observational study. The data were obtained from the Osteocenter of University Hospital in Hradec Kralove, Czech Republic. Adherence was measured using electronic bottles type Medication Events Monitoring System (MEMS). The study was carried out in two 3-month periods; the baseline in 2013 (signing of informed consent while medical check-up) and the follow-up (medical check-up) in 2014. The adherence and adherence-related outcomes were studied in patients who had initiated osteoporosis treatment and were persistent. Results: 21 (49%) out of 43 patients who avoided drug dispenser and were persistent both at baseline and at follow-up, completed the study and were included. Median age was 76. Evaluating the whole 3-month periods, the OA did not differ significantly at baseline and at follow-up, the OA was 71 and 68%, respectively. However, the adherence in month 1 at baseline was significantly higher than the adherence in month 2 at baseline (p < 0.001) and also than the adherence in month 1 at follow-up (p = 0.010). Analysing the study period without month 1, a stable adherence was observed in 48% of patients. About 33% of doses were omitted at baseline and 34% at follow-up. As many as 71% of the patients took drug holidays at baseline, and 76% at follow-up. Conclusion: The OA was insufficient, around 70% both at baseline and at follow-up. One half of the patients showed a stable adherence. The patterns of non-adherence were very similar at follow-up. Signing of the informed consent seems to act as bias more than regular medical check-up.

Adherence to denosumab in the treatment of osteoporosis and its utilization in the Czech Republic.

OBJECTIVES: The objective was to analyze adherence and current trends in utilization and prescription practice patterns of the anti-RANKL monoclonal antibody denosumab in the treatment of postmenopausal osteoporosis (OP). METHODS: The prescription-based database of the General Health Insurance Company of the Czech Republic that covers approximately 60% of the Czech population (6 million) was used as the data source. Medication possession ratio (MPR) and persistence were calculated for all patients (both OP medication-naïve and medication-experienced) with postmenopausal OP from the start of their therapy with denosumab 60 mg per ml subcutaneous injection within a period between September 2011, i.e. first denosumab availability, and May 2014. Clinical data such as fractures, co-morbidities and co-medication were not analyzed. RESULTS: A total of 7904 women treated with denosumab were analyzed; 93.8% of patients were identified as compliant (MPR ≥0.8) while 6.2% were non-compliant (MPR < 0.8). Persistence (base case, i.e. refill gap ≤30 days) was 59.1% after 12 months and 34.8% after 24 months. By 2013, i.e. within 2 years, denosumab became the second most utilized and most costly drug after oral bisphosphonates. CONCLUSIONS: Despite relatively high MPR and persistence rate observed in denosumab treatment, adherence enhancing strategies, focused on persistence in particular, are still needed. The uptake of denosumab has been rapid, its utilization keeps rising swiftly, and denosumab already represents a significant part of the osteoporosis therapy budget.

The impact of changes in national prescribing conditions for statins on their public expenditure and utilization in the Czech Republic 1997-2013.

OBJECTIVES: In the Czech Republic (CZ) extensive price regulation and prescribing conditions are common instruments often employed with new drugs. Since the introduction of statins onto the market in 1990s the originally strict conditions gradually relaxed while the prescription rates and public costs were rising. The aim was to analyze long-term utilization trends of statins, changes in their reimbursement prices and prescribing conditions, and the evolution of the market. METHODS: From January 1997 to December 2013 statin use was measured in terms of defined daily doses per 1000 insured per day (DDD/TID). The prescription-based database of the General Health Insurance Company of the Czech Republic in 1997 covering 7825,216 inhabitants, i.e. 76% of CZ population, was used as the administrative data source. Also the overall expenditure, unit prices, and reimbursement criteria were analyzed. RESULTS: Between 1997 and 2013 the utilization of statins rose from 2 to 96 DDD/TID while the expenditure rose 5.5-fold. The rise of prescription for each molecule was always observed after the liberation of the prescribing criteria. In the study period reimbursement prices of simvastatin and atorvastatin gradually decreased to just 5% of their initial values. CONCLUSIONS: The rising consumption of statins in CZ clearly corresponds in time with the liberation of prescribing conditions allowing for prescription by general practitioners and with the introduction of generics accompanied by a swift and repeated reimbursement price cuts.

Protective effect of heme oxygenase induction in ethinylestradiol-induced cholestasis.

Estrogen-induced cholestasis is characterized by impaired hepatic uptake and biliary bile acids secretion because of changes in hepatocyte transporter expression. The induction of heme oxygenase-1 (HMOX1), the inducible isozyme in heme catabolism, is mediated via the Bach1/Nrf2 pathway, and protects livers from toxic, oxidative and inflammatory insults. However, its role in cholestasis remains unknown. Here, we investigated the effects of HMOX1 induction by heme on ethinylestradiol-induced cholestasis and possible underlying mechanisms. Wistar rats were given ethinylestradiol (5 mg/kg s.c.) for 5 days. HMOX1 was induced by heme (15 µmol/kg i.p.) 24 hrs prior to ethinylestradiol. Serum cholestatic markers, hepatocyte and renal membrane transporter expression, and biliary and urinary bile acids excretion were quantified. Ethinylestradiol significantly increased cholestatic markers (P ≤ 0.01), decreased biliary bile acid excretion (39%, P = 0.01), down-regulated hepatocyte transporters (Ntcp/Oatp1b2/Oatp1a4/Mrp2, P ≤ 0.05), and up-regulated Mrp3 (348%, P ≤ 0.05). Heme pre-treatment normalized cholestatic markers, increased biliary bile acid excretion (167%, P ≤ 0.05) and up-regulated hepatocyte transporter expression. Moreover, heme induced Mrp3 expression in control (319%, P ≤ 0.05) and ethinylestradiol-treated rats (512%, P ≤ 0.05). In primary rat hepatocytes, Nrf2 silencing completely abolished heme-induced Mrp3 expression. Additionally, heme significantly increased urinary bile acid clearance via up-regulation (Mrp2/Mrp4) or down-regulation (Mrp3) of renal transporters (P ≤ 0.05). We conclude that HMOX1 induction by heme increases hepatocyte transporter expression, subsequently stimulating bile flow in cholestasis. Also, heme stimulates hepatic Mrp3 expression via a Nrf2-dependent mechanism. Bile acids transported by Mrp3 to the plasma are highly cleared into the urine, resulting in normal plasma bile acid levels. Thus, HMOX1 induction may be a potential therapeutic strategy for the treatment of ethinylestradiol-induced cholestasis.

Drug holidays: the most frequent type of noncompliance with calcium plus vitamin D supplementation in persistent patients with osteoporosis.

PURPOSE: All current recommendations include calcium and vitamin D (Ca-D) as an integrated part of osteoporosis treatment. The purpose of this pilot study was to analyze compliance with a fixed combination of Ca-D in women persistent with the treatment. PATIENTS AND METHODS: An observational study was carried out in three osteocenters in the Czech Republic. Women with osteoporosis ≥55 years of age concurrently treated with oral ibandronate were eligible. Compliance was evaluated in a period of 3 months by Medication Event Monitoring System (MEMS), tablet count, and self-report. Nonpersistence was defined as a MEMS-based gap in the use of Ca-D to be 30 days or more. RESULTS: A total of 73 patients were monitored, of which 49 patients were analyzed (target population). Based on MEMS, mean overall compliance was 71%; good compliance (≥80%) was observed in 59% of the patients. As many as 71% of the patients took drug holidays (≥3 consecutive days without intake); overall compliance of these patients was 59% and was slightly lower on Fridays and weekends. Patients without drug holidays were fully compliant (did not omit individual doses). Compliance differed according to daily time at which the patients mostly used the Ca-D. Afternoon/evening takers showed a mean overall compliance of 82% while morning/night takers only 51% (P=0.049). Based on MEMS, tablet count, and self-report, compliance ≥75% was observed in 59%, 100%, and 87% of the patients, respectively. Outcomes obtained by the three methods were not associated with each other. Undesirable concurrent ingestion of Ca-D and ibandronate was present only twice. CONCLUSION: Despite almost perfect self-reported and tablet count-based compliance, MEMS-based compliance was relatively poor. Consecutive supplementation-free days were common; more than two-thirds of the patients took at least one drug holiday. This pilot study showed drug holiday to be the most important type of noncompliance with Ca-D in those who are persistent with the treatment.

Consumption of osteoanabolic drugs and strontium ranelate in the treatment of osteoporosis in the Czech Republic in 2005-2011.

Anti-osteoporosis drugs with osteoanabolic (teriparatide, intact parathormone) and dual (strontium ranelate) mechanism of action are currently available for the treatment of postmenopausal, glucocorticoid induced or male osteoporosis in the Czech Republic (CZ). These expensive drugs are subjects of special prescribing limitations (2nd line treatments). The objective was to analyze trends in consumption of osteoanabolic and dual drugs in the treatment of osteoporosis since their introduction onto the market in CZ (2005-2011). The prescription-based database of the General Health insurance Company of the Czech Republic that covers approximately 60% of the Czech population was used as the data source. An insured person with a recorded prescription for teriparatide (TRPD), intact parathormone (iPTH) or strontium ranelate (SR) in the period of interest was defined as a patient; 271 (224), 77 (75) and 5930 (5545) patients (women) treated with TRPD, iPTH and SR in 2011, respectively, were identified. The median age of patients on TRPD and SR ranged from 71 to 74 years in 2006-2011. The number of patients treated with TRPD between 2009 and 2011 has been stable, while in iPTH the number increased 2.8 times in the same time period. The number of patients treated with SR has been steadily rising since its introduction in 2005. SR was prescribed most often by physicians specialized in internal medicine (42%) and rheumatology (25%). Male patients accounted for 6% of the SR consumers in 2011. The consumption of dual and osteoanabolic drugs has been rapidly increasing. Consumption rates in men (both absolute and relative) have been increasing but still remain relatively low.

Modification of hepatic iron metabolism induced by pravastatin during obstructive cholestasis in rats.

AIMS: To evaluate iron biochemistry and contributing liver mechanisms during obstructive cholestasis and pravastatin treatment in rats. MAIN METHODS: A rat model of cholestasis induced by bile duct ligation (BDL) was used for the study. The detection of iron and the expression of relevant molecules were performed one week after surgery in the control, and cholestatic animals after treatment with either saline or pravastatin (1mg/kg/day). KEY FINDINGS: Saline-administered BDL rats showed, in comparison to sham-operated animals, a significant increase in plasma iron concentration, increased liver protein content of heme oxygenase-1 (HO-1) and a decline in the expression of hepcidin. Ferroportin 1 expression was increased with a simultaneous reduction in intrahepatic iron concentration. The administration of pravastatin to BDL animals attenuated proliferation changes in liver parenchyma, prevented HO-1 induction, restored hepatic mRNA hepcidin expression to control levels and induced the expression of ferritin, transferrin receptors (TfR1/2) and divalent metal transporter-1. This was accompanied by an increased content of intrahepatic iron when compared to the BDL animals, and a reduction of hyperbilirubinemia. SIGNIFICANCE: Cholestasis-induced increase in plasma and decrease in hepatic iron levels were associated with up-regulation of liver HO-1 and ferroportin 1. Pravastatin alleviated cholestatic liver impairment and raised liver iron content by modulation of heme catabolism and an increase of hepatic iron uptake and storage capacity.

Pravastatin modulates liver bile acid and cholesterol homeostasis in rats with chronic cholestasis.

BACKGROUND AND AIM: The administration of pravastatin to patients with cholestatic liver disease has suggested the potential of the drug with regard to reducing raised plasma cholesterol and bile acid levels. Information about the mechanisms associated with this effect is lacking. Thus, the aim of the present study is to evaluate pravastatin effects on the liver bile acid and cholesterol homeostasis in healthy and cholestatic rats. METHODS: Control sham-operated and reversibly bile duct-obstructed (BDO) rats were treated with pravastatin (1 or 5 mg/kg) or the vehicle alone for 7 days after surgery. RESULTS: Lower doses of pravastatin reduced bile acid plasma concentrations in cholestatic animals. The effect was associated with reduced liver mRNA expression of Cyp7a1, Cyp8b1, Mrp2, Ugt1a1 and the increased expression of Bsep. In addition, BDO-induced increase in the liver content of cholesterol was normalized by pravastatin. The change was accompanied by the reduced liver expression of Hmg-CoA reductase, LDL receptor, and Acat2, and induced the expression of Abca1 and Mdr2. These changes corresponded with the upregulation of nuclear receptors LXRα and PPARα, and the downregulation of FXR, CAR, SREBP-2 and HNF1α. High doses of pravastatin lacked any positive effects on bile acids and cholesterol homeostasis, and blocked bile formation through the reduction of the biliary excretion of bile acids. CONCLUSIONS: Pravastatin rendered a positive reduction in BDO-induced increases in plasma bile acid concentrations and cholesterol liver content, mainly through the transcriptionally-mediated downregulation of genes involved in the synthesis of these compounds in the liver.

Dexamethasone reduces methotrexate biliary elimination and potentiates its hepatotoxicity in rats.

Increased hepatotoxicity of methotrexate has been reported during dexamethasone therapy in humans. Despite the observed inducing effect of dexamethasone on some methotrexate transporting proteins in the liver, the kinetic aspects of this interaction have not been studied yet. Thus, the aim of the present study was to evaluate the influence of dexamethasone on the hepatic and overall pharmacokinetics of methotrexate. Pharmacokinetics of methotrexate was evaluated in rats during an in vivo steady-state clearance study after either single intravenous dose of dexamethasone or its four-day oral administration in a dose optimized for transport proteins induction. Dexamethasone oral pretreatment reduced biliary clearance of methotrexate by 53%. Although liver tissue concentration of methotrexate increased only slightly in these animals, a significant increase in liver weights produced by dexamethasone pretreatment revealed a marked increase in liver content of the drug. An evaluation of plasma liver enzyme activities measured before and after methotrexate administration demonstrated a potentiation of corticosteroid hepatotoxicity by the cytostatic. Analysis of methotrexate transporter expression in the liver showed up-regulation of Mrp2, Oatp1a4, and Oat2, and down-regulation of Mrp3. These observations comply with increased biliary excretion and reduced plasma concentrations of their endogenous substrate, conjugated bilirubin. In contrast, single intravenous bolus of dexamethasone did not influence any pharmacokinetic parameter of methotrexate. In conclusion, these results indicate that hepatocellular impairment associated with reduced biliary elimination of methotrexate, and its raised liver content may contribute to increased hepatotoxicity of the drug when co-administered with dexamethasone. Moreover, an influence of dexamethasone on protein expression of anionic drugs transporters in the liver and kidney was demonstrated.

Methotrexate released in vitro from bone cement inhibits human stem cell proliferation in S/G2 phase.

Methotrexate (MTX) released from bone cement showed a useful local effect in animal models of bone tumours. However, local toxic reactions such as impaired wound healing were observed in areas surrounding the MTX-loaded implant. Therefore, we hypothesised that MTX released from bone cement would have harmful effects on human mesenchymal stem cells (MSC)-one of the basic components of bone marrow and tissue reparatory processes. Moreover, elution of MTX was calculated from implants prepared either with liquid or powdered MTX. During the 28-day incubation, the cement compounded with liquid MTX showed the highest elution rate of the drug. MTX released from pellets produced a significant decrease in proliferation of MSC as a consequence of a blockade of their cell cycle in the S/G2 phase. These findings indicate impairment of stem cell function in marginal areas surrounding the MTX-loaded cement and may help to explain problems with regeneration of tissues in these locations.

Up-regulation of renal Mdr1 and Mrp2 transporters during amiodarone pretreatment in rats.

Although amiodarone (AMD) is known to produce drug-drug interactions through inhibition of transporter-mediated excretion of drugs, its impact on these mechanisms during chronic treatment has not been described yet. Therefore, the aim of this study was to investigate the influence of AMD pretreatment on the main multidrug transporting proteins, Mdr1 and Mrp2, in the liver and kidney. The expression of the transporters and pharmacokinetics of their substrates, rhodamine-123 (Rho123) and endogenous conjugated bilirubin (CB), were evaluated in rats after either AMD oral pretreatments (4-14 days) or single intravenous bolus. AMD pretreatment of all durations up-regulated renal Mdr1 and Mrp2 protein expression to 155-190% and 152-223% of the control values, respectively. In agreement, we observed a corresponding increase in renal clearance of both substrates. Hepatic expression was increased only for Mdr1 to 234-270% of controls, which was associated with increased biliary elimination of amiodarone without change in Rho123 biliary clearance. Interestingly, hepatic expression of another Mdr transporter, Mdr2, was progressively decreased by amiodarone administration. Acute administration of AMD reduced Rho123 biliary clearance by 64%. Our results indicate that repeated administration of AMD to rats is associated with significant increase in hepatic and renal expression of Mdr1 and Mrp2 transporters, which may contribute to variability in pharmacokinetics of AMD and simultaneously applied drugs.

Alteration of methotrexate biliary and renal elimination during extrahepatic and intrahepatic cholestasis in rats.

Methotrexate (MTX), an important anticancer and immunosuppressive agent, has been suggested for the treatment of primary biliary cirrhosis. However, the drug's pharmacodynamics and toxicity is dependent on its concentrations in plasma which in turn are directly related to MTX's elimination in the liver and kidney. Therefore, the aim of this study was to evaluate changes in MTX biliary and renal excretion during either intrahepatic or obstructive cholestasis in rats. The steady state pharmacokinetic parameters of MTX were evaluated in rats one (BDO1) or seven (BDO7) days after bile duct obstruction (BDO) or 18 h after administration of lipopolysaccharide (LPS). In comparison to the respective control groups, biliary and total clearances of MTX were decreased to 12% and 49% in the BDO1 group, to 5% and 56% in the BDO7 animals, and to 42% and 43% in the LPS group, respectively. Renal clearance of MTX was unchanged in BDO groups, but decreased to 23% of controls in the LPS animals. The serum biochemistry and expression of main hepatic MTX transporters (Mrp2, Mrp3, Mrp4, Bcrp, Oatp1a1, Oatp1a4 and Oatp1b2) confirmed the pathological cholestatic changes in the liver and partly elucidated the cause of changes in MTX pharmacokinetic parameters. In conclusion, this study is the first describing marked alteration of MTX hepatic and renal elimination induced by cholestasis in rats. Moreover, the reported changes in MTX pharmacokinetics and respective transporter expression suggest important mechanistic differences between the two widely used cholestatic models.

Amiodarone modulates pharmacokinetics of low-dose methotrexate in rats.

Clinical studies of low-dose methotrexate (LDMTX) pharmacokinetics document increased plasma concentrations of MTX after co-administration of the drug with amiodarone or macrolide antibiotics. As drug-drug interactions may increase the toxicity of LDMTX, a rat model was used to follow renal and biliary elimination of MTX during its constant-rate i.v. infusion and concomitant single bolus i.v. injections of amiodarone or azithromycin. The mean steady-state plasma concentration of 1.7+/-0.1 micromol/l was reached and the total clearance achieved 17.7+/-1.0 ml/min/kg. Administration of amiodarone decreased the biliary clearance of MTX to 73% of the control values (p<0.05). Correspondingly, the total clearance decreased to 72% and plasma MTX concentrations were augmented to 2.5+/-0.4 micromol/l (p<0.05). Amiodarone-treated rats exhibited a 3.3-fold decrease in the renal clearance (p<0.05) of conjugated bilirubin, which was associated with its increased plasma concentration. In contrast, azithromycin did not alter any of the MTX pharmacokinetic parameters. In conclusion, this is the first report describing the impairment of MTX hepatic elimination during co-administration with amiodarone. This study also provides new insight into acute amiodarone-induced hyperbilirubinaemia, where increased bilirubin production and decreased renal clearance may contribute to this effect. Importantly, azithromycin seems to be a safe co-medication during LDMTX therapy.

P-glycoprotein function and expression during obstructive cholestasis in rats.

OBJECTIVES: The present study was aimed at evaluation of in vivo biliary and renal excretion of rhodamine 123 (Rho123), a P-glycoprotein (P-gp) substrate, in rats during either acute or chronic cholestasis induced by bile duct obstruction (BDO). METHODS: The Rho123 clearance study was performed either one (BDO1) or seven (BDO7) days after BDO. Bile flow was reconstituted, and bile and urine were collected after steady-state plasma concentration of Rho123 was attained. Tissue expression of P-gp was evaluated by quantitative immunohistochemistry, and immunoblotting. RESULTS: Significant up-regulation of the liver P-gp protein was observed in acute and chronic cholestasis. Primary periportal location of P-gp was enlarged also to pericentral areas. In the kidneys, immunohistochemistry showed pancellular increase in P-gp after 1 day of BDO, which subsided after 7 days of BDO. Nevertheless, biliary and renal clearances (CL(Bile) and CL(R)) of Rho123 did not reflect the induction of P-gp expression. While CL(Bile) was reduced one day after cholestasis and restored on the seventh day, the CL(R) was preserved in BDO1 group and reduced in BDO7 group without change in glomerular filtration rate. In parallel, biliary and renal clearances of conjugated bilirubin were significantly reduced in both cholestatic groups compared with controls. CONCLUSION: These findings suggest that extrahepatic cholestasis causes time-dependent changes in elimination of Rho123 which do not exactly reflect alteration of P-gp expression in the rat liver and kidney. These data may help to explain impaired elimination of P-gp substrates after short-term cholestasis that may commonly occur in clinical practice.

Specific oxidative stress parameters differently correlate with nailfold capillaroscopy changes and organ involvement in systemic sclerosis.

Oxidative stress is suggested to be involved in the pathogenesis of systemic sclerosis (SSc). The aim of the present study was to clarify such a hypothesis by determination of four different plasmatic parameters of oxidative stress, and to define its role in the microvascular damage, assessed by nailfold capillaroscopy (NC). Plasma samples of 18 patients with SSc were analyzed. The biomarkers measured were: total antioxidant capacity, hydroperoxides (ROOHs), and sulfhydryl (SH) and carbonyl (CO) groups. Each patient had a detailed clinical assessment and underwent an NC. The results showed significantly increased ROOHs in SSc patients compared to control group (5.02 +/- 0.24 vs 3.28 +/- 0.19 micromol/l; p < 0.05). Plasmatic levels of SH groups were significantly lower in SSc (0.466 +/- 0.08 mmol/l) compared to control group (0.542 +/- 0.04 mmol/l; p < 0.002). Plasma levels of ROOHs correlated with the capillaroscopy semiquantitative rating scale score (p < 0.05) and with the rating system for avascular areas (p < 0.03). The levels of CO groups inversely correlated with modified Rodnan's skin score (p < 0.039) and were lower in patients with pulmonary fibrosis (p < 0.045), while the levels of SH groups were lower in those presenting gastrointestinal involvement (p < 0.029). The obtained data indicate augmented free radical-mediated injury in SSc and also show correlations among oxidative abnormalities, some clinical findings, and signs of a more severe microvascular involvement. These results give more evidence to the connection between oxidative impairment and SSc.

Zonation of multidrug resistance-associated protein 2 in rat liver after induction with dexamethasone.

BACKGROUND AND AIM: The present study was aimed to evaluate the hepatic zonation of multidrug resistance-associated protein 2 (mrp2), an important drug transporter, and its potential changes during the induction of its expression by known inducer, dexamethasone (DEX). METHODS: The hepatic expression of mrp2 was studied by immunohistochemistry with consequent quantification by measurement of integral optical densities of mrp2 staining in the periportal and perivenous areas of the liver acinus in control and DEX-pretreated rats (1 mg/kg daily per os for 4 days). Overall changes in mrp2 expression and function produced by DEX were monitored using Western blotting and an in vivo clearance study of endogenous-conjugated bilirubin, a mrp2 substrate. RESULTS: In the control animals, a quantitative image analysis revealed the primary periportal localization of mrp2 within the liver acinus with the expression of mrp2 being 16.7-fold of that in the perivenous area. After DEX pretreatment, the expression of mrp2 increased, especially in the perivenous hepatocytes. The overall expression of mrp2 increased 3.2-fold in comparison with the control group. This observation was confirmed by Western blotting, which showed a 1.3-fold increase in the mrp2 protein after DEX pretreatment. The functional consequences of the induced mrp2 protein in the livers of the DEX-pretreated rats were demonstrated by the increased biliary excretion of conjugated bilirubin. CONCLUSION: In conclusion, these results indicate the zonation of mrp2 protein expression primarily to periportal hepatocytes. The induction by DEX produced spatially disproportional changes with an increase in the mrp2 protein being most prominent in the perivenous hepatocytes.

Morphological and functional changes in p-glycoprotein during dexamethasone-induced hepatomegaly.

1. The effect of dexamethasone on hepatic and renal P-glycoprotein (P-gp) expression, localization and activity was investigated in rats after 4 days oral administration of two dose regimens (1 or 25 mg/kg per day). Simultaneous increases in liver weight were evaluated by quantitative histological examination. 2. In the liver, dexamethasone pretreatment produced hepatomegaly as a consequence of extensive periportal fat accumulation, which was quantified by densitometry of oil red O-stained liver sections. Quantitative immunohistochemical analysis revealed preferential periportal zonation of P-gp in control animals. Dexamethasone pretreatment resulted in spatially disproportional induction of P-gp protein expression within the liver acinus characterized by preferential increase in pericentral areas, with consequent uniform panlobular distribution. Western blot analysis confirmed these results, showing increases in P-gp protein. Quantitative reverse transcription-polymerase chain reaction analysis revealed no statistically significant change in liver mdr1b mRNA expression after either dexamethasone treatment regimen. The expression of mdr1a mRNA was significantly decreased by 85-87%. 3. In the kidney, dexamethasone reduced mdr1a mRNA expression by 69-89%, whereas mdr1b mRNA expression was increased in a dose-dependent manner. However, despite tendencies, no significant increases in P-gp expression were observed at the protein level. 4. The in vivo function of P-gp was evaluated by measuring renal and biliary secretion of rhodamine-123 (Rho123) under a steady state plasma concentration. The biliary, renal and tubular secretory clearance of Rho123 was significantly increased only after high-dose dexamethasone. 5. In conclusion, the present study suggests that drug interactions observed during corticosteroid therapy may be mediated, at least in part, through increased biliary, and also renal, excretion of P-gp substrates. Expression of P-gp in the liver showed primary periportal zonation with differential changes during induction. Accompanying hepatomegaly may be explained by severe microvesicular steatosis selectively localized to the periportal areas.