Slobodan Jankovic

Induction of CYP1A2 by heavy coffee consumption is associated with the CYP1A2 −163C>A polymorphism

ObjectivesTo investigate the association of CYP1A2 genetic polymorphisms with the inducing effect of heavy coffee consumption on CYP1A2 activity in Serbian and Swedish populations, and to determine the frequency of the CYP1A2 genetic polymorphisms in Serbs.MethodsUsing PCR-RFLP and the tag-array minisequencing method, 126 Serbian healthy volunteers were genotyped for −3860G>A, −2467delT, −739T>G, −729C>T, −163C>A, 2159G>A, and 4795G>A. For 64 nonsmoking participants, the data on CYP1A2 activity (plasma paraxanthine/caffeine ratio) and coffee consumption habit were available from our previous study. The data on CYP1A2 genotype, enzyme activity, and coffee consumption from 114 Swedish healthy nonsmoking subjects were included in the analyses.ResultsIn Serbs, CYP1A2 polymorphisms −3860G>A, −2467delT, −739T>G, −729C>T, −163C>A, and 2159G>A were found at the frequencies of 0.4, 5.0, 3.4, 0.7, 61.1, and 56.0%, respectively, while 4795G>A was not detected. Significant association of heavy coffee consumption with high CYP1A2 enzyme activity was observed only in carriers of −163 A/A. Increasing effect of −163C>A on CYP1A2 inducibility was found in both Serbian (P = 0.022) and Swedish (P = 0.016) nonsmoking heavy coffee consumers. There was no significant difference in CYP1A2 enzyme activity among genotypes in non–heavy coffee consumers. The results indicate that 22 and 14% of the phenotypic variability among Serbian and Swedish heavy coffee consumers, respectively, might be explained by −163C>A polymorphism.ConclusionsCYP1A2 polymorphism −163C>A has an important increasing effect on CYP1A2 inducibility by heavy coffee consumption and may possibly be a contributing factor for interindividual variations in CYP1A2 enzyme activity.

Evernia prunastri and Pseudoevernia furfuraceae lichens and their major metabolites as antioxidant, antimicrobial and anticancer agents

The aim of this study is to investigate chemical composition of acetone extracts of the lichens Evernia prunastri and Pseudoevernia furfuraceae and in vitro antioxidant, antimicrobial, and anticancer activities of these extracts and some their major metabolites. HPLC-UV method was used for identification of secondary metabolites. Antioxidant activity was evaluated by free radical scavenging, superoxide anion radical scavenging, reducing power and determination of total phenolic compounds. As a result of the study physodic acid had largest antioxidant activities. Total content of phenol in extracts was determined as pyrocatechol equivalent. The antimicrobial activity was estimated by determination of the minimal inhibitory concentration by the broth microdilution method. The most active was also physodic acid. Anticancer activity was tested against FemX (human melanoma) and LS174 (human colon carcinoma) cell lines using MTT method.

Evolution of the Serbian pharmaceutical market alongside socioeconomic transition.

Introduction: South-eastern European socioeconomic transition followed by extensive health systems reforms has completely changed the pharmaceuticals market landscape in the region. Serbia, as the largest Western Balkans market, may serve as an example of such changes. Methods: Descriptive trend analysis of national-level dispensing of medicines in Serbia 2004–2012 was performed. Results: Total public health expenditure in Serbia increased sharply in less than a decade (€1,175,158,679 to €1,847,971,776); public spending on pharmaceuticals doubled (€339,279,304 to €742,013,976). Market growth was primarily driven by statins, novel platelet aggregation inhibitors, monoclonal antibodies and combined preparations indicated in asthma and chronic obstructive pulmonary disease. Conclusion: The pharmaceutical market of Serbia has undergone thorough and complete transformation from within. Serious crisis of medicine supply sustainability is currently shaking Balkan health systems due to increasing public debt worsened by global recession. More responsible reimbursement policy rooted in cost–effectiveness principle is needed in years to come.

N‐acetyltransferase‐2 (NAT2) Gene Polymorphisms and Enzyme Activity in Serbs: Unprecedented High Prevalence of Rapid Acetylators in a White Population

The aim of this study was to investigate N‐acetyltransferase 2 (NAT2) genetic polymorphism and enzyme activity in Serbs, and to examine the influence of NAT2 genotype, sex, and smoking on the phenotype. Genotyping for 190C>T, 282C>T, 341T>C, 403C>G, 411T>A, 481C>T, 590G>A, 803A>G, and 857G>A in the NAT2 gene, was performed in 140 healthy Serbs. NAT2 activity was determined as AFMU/(AFMU + 1X + 1U) urinary ratio in 100 subjects using caffeine as a probe. The most frequent NAT2 haplotypes were NAT2*5B (38.2%), NAT2*6A (26.0%), and NAT2*4 (24.4%). The log‐transformed NAT2 activity indices exhibited trimodal distribution with 9%, 36%, and 55% of slow, intermediate, and rapid acetylators, respectively. Significant NAT2 genotype‐phenotype correlation was observed (P < .0001). The frequency of NAT1*10 and NAT1*11 were 27.5% and 6.9%, respectively. There was no significant influence of sex or cigarette smoking on NAT2 enzyme activity. Eight subjects displayed rapid NAT2 acetylators phenotype despite being homozygous for NAT2 slow alleles, and NAT1 fast acetylators genotype (NAT1*10 and NAT1*11) had no implication. In contrast to other white populations described hitherto, rapid acetylator is the predominant NAT2 phenotype in Serbs. NAT2 genotype, but not sex and cigarette smoking, influence enzyme activity. NAT1 fast acetylators genotypes do not contribute for NAT2 genotype‐phenotype discordance.

Choice of antiepileptic drugs for the elderly: possible drug interactions and adverse effects

Introduction: Antiepileptic drugs are prescribed to patients of all ages and are commonly prescribed to patients over the age of 65. When prescribing these drugs to patients of this age bracket, treatment should be based not only on the diagnosis and seizure type but also on the propensity of the drugs for adverse effects and their drug–drug interactions. Areas covered: This article reviews antiepileptic drugs currently used for treating the elderly and highlights the adverse effects and potential drug–drug interactions for these treatments. The article was complied through literature searches of the Cochrane database of systematic reviews, MEDLINE and SCindeks. Expert opinion: In elderly patients who have hepatic diseases, antiepileptic drugs that are not metabolized in the liver, such as levetiracetam, are preferred; in patients with moderate and severe renal failure, carbamazepine and valproic acid are the preferred antiepileptic drugs. Phenytoin, fosphenytoin, carbamazepine, oxcarbazepine and lamotrigine should not be prescribed in elderly patients with cardiac conduction abnormalities or a history of ventricular arrhythmia. While the majority of antiepileptic drugs interact with other drugs, hepatic enzymes and plasma proteins, a few newer antiepileptic drugs are free from such interactions (e.g., gabapentin, levetiracetam and tiagabine), which make them suitable candidates for elderly patients. However, in order to make further recommendations regarding the choice and dosing regimens of antiepileptic drugs in elderly patients, more extensive clinical research in this specific population is necessary.

Population pharmacokinetics of lamotrigine in patients with epilepsy.

OBJECTIVE The purpose of this study was to derive a population pharmacokinetics (PPK) model of lamotrigine clearance as well as to identify and describe factors that influence it in Serbian patients with epilepsy. METHODS A total of 40 steady-state serum concentrations from 38 adult and pediatric patients with epilepsy, collected during routine therapeutic drug monitoring, were used for the analysis. To determine the influence of different covariates on the estimate of lamotrigine clearance we built a non-linear mixed-effects one-compartment model with the first order elimination and without absorption. RESULTS Typical mean value of lamotrigine clearance, estimated by the base model (without covariates), in our population was 1.15 l h-1. The final model showed that lamotrigine clearance increased with total body weight, daily dose and concomitant administration of carbamazepine, and decreased with concomitant administration of valproate. The magnitude of carbamazepine and valproate effect was +1.13 l h-1 and -1 l h-1, respectively. The final model was validated in a group of 15 epileptic patients, showing good predictive performance. CONCLUSIONS The derived model describes well lamotrigine clearance in terms of characteristics of Serbian patients, offering basis for rational individualization of lamotrigine dosing regimens.

Unexpected effect of furosemide on radioiodine urinary excretion in patients with differentiated thyroid carcinomas treated with iodine 131.

BACKGROUND In patients receiving (131)I for therapeutic purposes, diuretics are frequently used in an attempt to accelerate elimination of unbound radioiodine, reduce its adverse effects, and shorten the hospital stay. The aims of our study were to investigate the influence of furosemide therapy on urinary excretion of (131)I in patients with differentiated thyroid cancer (DTC), referred to radioiodine ablation after thyroidectomy, and to investigate whether diuretics are useful in daily practice in patients with DTC. METHODS Forty-three patients with DTC who had normal renal function and low (131)I uptake in cervical region (3.55 +/- 3.45%) were included in this study. The furosemide (20 mg) and potassium chloride (250 mg) were given orally to 23 patients 3 hours after the (131)I administration, and then q8h for 3 days. Twenty patients did not receive either furosemide or potassium chloride. After (131)I administration, the patients collected their urine for 3 days, and radioactivity of urine sample from each micturition was expressed as percentage of the administered dose. Radioactivity of blood samples was measured after 72 hours, and the values were corrected for decay of (131)I and expressed in relation to the administered dose. Initial whole-body measurement (immediately after (131)I administration) and the whole-body measurement after 72 hours were recorded for all patients. The 72-hour whole-body measurement was corrected for decay of (131)I, and expressed as a percentage of the initial whole-body measurement. RESULTS Urinary excretion of (131)I was significantly lower in the patients who were taking furosemide and potassium chloride compared with the control group. The whole-body measurements after 72 hours (13.22 +/- 6.55% vs. 8.24 +/- 3.39% of the initial; p < 0.01, respectively) and the blood radioactivity (34.66 +/- 24.84 vs. 11.64 +/- 8.32 cpm/mL per 1 MBq of administered (131)I, p < 0.01) were found to be unexpectedly higher in the patients who were taking furosemide and potassium chloride compared with the control group. CONCLUSION Our results demonstrated that furosemide given as an adjuvant medication in patients with DTC causes a significant decrease in urinary excretion of radioiodine and its higher blood concentration. Therefore, furosemide should not be recommended as an adjuvant therapy to radioiodine ablation in patients with DTC previously iodine depleted by low-iodine diet.

Chemical and Antimicrobial Evaluation of Supercritical and Conventional Sideritis scardica Griseb., Lamiaceae Extracts

Sideritis scardica Griseb., Lamiaceae (ironwort, mountain tea), an endemic plant of the Balkan Peninsula, has been used in traditional medicine in the treatment of antimicrobial infections, gastrointestinal complaints, inflammation and rheumatic disorders. This study reports a comparison between conventional (hydrodistillation HD and solvent extraction SE) and alternative (supercritical carbon dioxide SC CO2) extraction methods regarding the qualitative and quantitative composition of the obtained extracts as analyzed by GC and GC-MS techniques and their anitimicrobial activity. Different types of extracts were tested, the essential oil EO obtained by HD, EO-CO2 and AO-CO2 obtained by SC CO2 at different preasures 10 and 30 MPa, at 40 °C, respectively, and the fractions A, B, C and D obtained by successive solvent extraction (SE) A: ethanol, B: diethyl ether, C: ethyl acetate and D: n-butanol). While EO was characterized by the presence of the high percentage of oxygenated monoterpenes and sesquiterpenes (30.01 and 25.54%, respectively), the rest of the investigated samples were the most abundant in fatty acids and their esters and diterpenes (from 16.72 to 71.07% for fatty acids and their esters, and from 23.30 to 72.76%, for diterpenes). Microbial susceptibility tests revealed the strong to moderate activity of all investigated extracts against the tested microorganisms (MIC from 40 to 2,560 μg/mL). Although differences in the chemical compositions determined by GC and GC-MS analysis were established, the displayed antimicrobial activity was similar for the all investigated extracts.

Population pharmacokinetics of tacrolimus in kidney transplant patients.

OBJECTIVE The purpose of this study was to derive population pharmacokinetics (PPK) model of tacrolimus clearance, identify and describe factors that influence it in Serbian kidney transplant patients. METHODS Population pharmacokinetics analysis was performed using nonlinear mixed-effects model (NONMEM) program from Serbian adult kidney transplant patients receiving triple immunosuppressive therapy, including oral tacrolimus. Details of drug dosage history, sampling time and tacrolimus concentration in 63 patients (44 males and 19 females), 27 - 57 years old (age mean 40.88 +/- 7.01 years) were collected retrospectively. Effects of several covariates on tacrolimus clearance were tested: total body weight, gender, age, posttransplantation days, hemoglobin count, CRP, alanine aminotransferase/aspartate aminotransferase, total daily dose of tacrolimus, co-medication with cotrimoxasole, omeprazole, mycophenolate mofetil and prednisone (> 25 mg). RESULTS Typical mean value of tacrolimus clearance, estimated by the base model (without covariates), in our population was 1.03 l h-1. The final model showed that tacrolimus clearance increased with total daily dose and concomitant administration of high-dose prednisone (> 25 mg). The magnitude of prednisone effect was + 1.16 l h-1. Final model was validated in a group of 17 patients, showing good predictive performance. CONCLUSIONS The derived model describes well tacrolimus clearance in terms of characteristics of Serbian kidney transplant patients, offering basis for rational individualization of tacrolimus dosing regimens.

Inverse correlation of valproic acid serum concentrations and quality of life in adolescents with epilepsy

BACKGROUND Correlation between steady-state serum concentrations of antiepileptic drugs and both seizure control and adverse drug reactions frequency (two major determinants of quality of life in patients with epilepsy) is still matter of controversy. OBJECTIVE The aim of our study was to investigate whether a correlation exists between steady-state serum concentration of valproic acid and quality of life in adolescent patients with epilepsy. METHOD Twenty-one adolescent patients with epilepsy, treated with valproic acid for more than 6 months entered the study. On two occasions, 3 months apart, both through and 2-h-after-the-dose serum concentrations of valproic acid were measured, as well as quality of life, using QOLIE-AD-48 for adolescents. Adverse drug reactions and seizure control were also recorded. RESULTS Significant inverse correlation between through serum concentrations of valproic acid and total QOLIE-AD-48 scores was observed, together with correlation between through serum concentrations and adverse drug reactions frequency. The scores of memory/concentration and physical functioning QOLIEAD-48 domains were significantly and inversely correlated with through serum concentrations. CONCLUSION Our study suggests that therapeutic monitoring of valproic acid serum concentrations could be useful predictor and marker of the most important epilepsy treatment outcome--quality of life.