Influence of methylxanthines isolated from Bancha green tea on the pharmacokinetics of sildenafil in rats.

BACKGROUND: Sildenafil is used to treat erectile dysfunction and pulmonary arterial hypertension and is metabolized in the liver mainly by CYP3A4, thus co-administration with drugs or herbal extracts that affect CYP3A4 activity may lead to drug-drug or drug-herb interactions, respectively. The aim of the present study was to evaluate the influence of single and multiple oral doses of methylxanthine fraction, isolated from Bancha green tea leaves on the pharmacokinetics of sildenafil in rats. METHODS: Rats were given sildenafil alone as well as simultaneously with methylxanthines or ketoconazole. The plasma concentrations of sildenafil were measured with high-performance liquid chromatography method with ultraviolet detection. The pharmacokinetic parameters of sildenafil were calculated by non-compartmental analysis. RESULTS: Concomitant use of sildenafil with a single oral dose of methylxanthines resulted in a decrease in Cmax (p > 0.05), AUC0-t (p < 0.05) and AUC0-inf (p < 0.05), while the administration of sildenafil after methylxanthines pretreatment resulted in an increase in Cmax (p < 0.0001), AUC0-t (p < 0.0001) and AUC0-inf (p < 0.001) compared to the sildenafil group. After co-administration of sildenafil and ketoconazole, a significant increase in Cmax, AUC0-t and AUC0-inf was observed in both of the experiments. CONCLUSION: Drug-herb interactions were observed when sildenafil was co-administered with Bancha methylxanthines in rats. Further in vivo studies about the potential drug interactions between sildenafil and methylxanthines, especially caffeine, are needed to clarify mechanisms underlying the observed changes in sildenafil pharmacokinetics.

Prevalence of polypharmacy and risk of potential drug-drug interactions among hospitalized patients with emphasis on the pharmacokinetics.

BACKGROUND: Both polypharmacy and potential drug-drug interactions (pDDIs), especially those at the pharmacokinetic level, are common in hospitalized patients and are associated with adverse effects and failure of therapy. OBJECTIVE: The aim of the present study is to investigate retrospectively the prevalence of polypharmacy and the risk of potential pharmacokinetic drug-drug interaction among hospitalized patients. METHODS: The medical documentation of hospitalized patients in the unit of internal diseases at the hospital "St Marina" in Varna, Bulgaria for a period of six months (January-July 2016) was retrospectively reviewed. Lexicomp® Drug Interaction software was used for the detection of pDDI. Descriptive statistic and logistic regression were used for data analysis. RESULTS: In this study, 294 patients out of 510 (57%) were selected with polypharmacy. The number of detected potential pharmacokinetic DDIs (pPKDDIs) was only 216 (or 12,4%), but almost 40% of patients with polypharmacy were exposed to at least one pPKDDIs. The most common pPKDDIs occur at the biotransformation level - 78 (36,1%), and the most common enzyme form that is involved in these interactions is cytochrome 3A4 (44 or 20,4%). The number of prescribed medications (>7) was found to increase the possibility of having pDDIs (OR 25.535, 95% CI 12.529 to 52.042; p = <0.001) and pPKDDIs (OR 5.165, 95% CI 3.430 to 7.779; p = <0.001) as well. CONCLUSION AND RELEVANCE: Caution should be taken in patients taking more than seven drugs and careful assessment of the pPKDDIs should be made. When such interactions are detected, they need to be properly evaluated and managed.

In vitro antiviral activities of fruit extract from Lycium barbarum and methylxanthines extracted from Pu-erh and Bancha tea leaves.

INTRODUCTION: Based on traditional medicine, many countries use various plant products (fruits, leaves and other plant parts) as food supplements or in the form of tea. The use of these plant sources has been established through the years of use and the proven benefits of their ingredients to improve human health.

Protective Effect of Methylxanthine Fractions Isolated from Bancha Tea Leaves against Doxorubicin-Induced Cardio- and Nephrotoxicities in Rats.

Doxorubicin is an anthracycline antibiotic that is used for the treatment of various types of cancer. However, its clinical usage is limited due to its potential life-threatening adverse effects, such as cardio- and nephrotoxicities. Nonetheless, simultaneous administration of doxorubicin and antioxidants, such as those found in green tea leaves, could reduce cardiac and renal tissue damage caused by oxidative stress. The methylxanthine fraction isolated from Bancha tea leaves were tested in vitro for its antioxidant activity and in vivo for its organoprotective properties against doxorubicin-induced cardio- and nephrotoxicities in a rat model. The in vivo study was conducted on male Wistar rats divided into 6 groups. Methylxanthines were administered at high (5 mg/kg body weight) and low (1 mg/kg body weight) doses, while doxorubicin was administered at a cumulative dose of 20 mg/kg body weight. Serum creatinine, uric acid, and urea concentrations, as well as serum enzyme levels (creatinine kinase (CK), creatinine kinase MB fraction (CK-MB), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH)) and electrolytes (Na+, K+, and Cl-), were analysed. In addition, histological analysis was performed to assess cardiac and renal tissue damage. The concomitant administration of Bancha methylxanthines and doxorubicin showed a dose-dependent reduction in the serum biochemical parameters, indicating a decrease in the cardiac and renal tissue damage caused by the antibiotic. Histological analysis showed that pretreatment with methylxanthines at the dose of 5 mg/kg resulted in an almost normal myocardial structure and a significant decrease in the morphological kidney changes caused by doxorubicin exposure compared with the group that received doxorubicin alone. The putative mechanism is most likely related to a reduction in the oxidative stress caused by doxorubicin.

The role of the clinical pharmacist in the prevention of potential drug interactions in geriatric heart failure patients.

Background The treatment of heart failure patients is very complex and includes lifestyle modification as well as different pharmacological therapies. Polypharmacy is very common in such patients and they are at increased risk of potential drug-drug interactions and associated effects such as poor adherence, compliance and adverse events. Objective The aim of the present study is to investigate retrospectively the prescribed pharmacotherapy of the hospital discharged heart failure patients for possible drug interactions. Settings Clinic for Cardiology of the "Saint Marina" University Hospital in Varna, Bulgaria. Method Lexicomp® Drug interaction software was used for screening potential drug-drug interactions. Logistic regression was applied to determine the odds ratio for the association between the age and number of drugs taken and the number of potential drug-drug interactions. Main outcome measure Incidence and type of pDDIs in geriatric heart failure patients. Results A retrospective study was conducted by reviewing the medical records of 248 selected heart failure patients for the prescribed medicines for a 1-year period (January 2015-December 2015). The total number of potential drug-drug interactions was 1532, or approximately 6.28 (± 4.72 SD) per one person. The range of prescribed drugs was between three and fourteen, 92% of them have been taking more than five medicines, an average of 7.12 (± 2.07 SD) per patient. The average age was 72.35 (± 10.16 SD). The results have shown stronger association between the number of drugs taken (more than 7) and the occurrence of potential drug-drug interactions (more than 10)-37.84 (95% CI 9.012-158.896, P ≤ 0.001). No statistically significant differences were found between age and occurrence of potential drug-drug interactions (more than 10)-1.008 (95% CI 0.441-2.308, P = 0.848). Conclusion The incidence of drug-drug interactions in heart failure patients is high. The clinical pharmacist, as a part of the multidisciplinary team, could reduce medication-related problems, such as drug interactions, and to optimize drug therapy by checking the treatment prescribed at the discharge of these patients.

Isolation, analysis and in vitro assessment of CYP3A4 inhibition by methylxanthines extracted from Pu-erh and Bancha tea leaves.

Methylxanthines, purine alkaloids found in plants, are found in beverages (coffee, tea, cocoa) and foods (chocolate and other cocoa-containing foods) commonly consumed worldwide. Members of this family include caffeine, theophylline and theobromine. Methylxanthines have a variety of pharmacological effects, and caffeine and theophylline are used as pharmaceuticals. Methylxanthines are metabolized in the liver predominantly by the enzyme CYP1A2. Their co-administration with CYP1A2 inhibitors may lead to pharmacokinetic interactions. Little is known about the possible drug interactions between caffeine and substrates of other CYP450 enzymes. In our study, methylxanthine fractions inhibited CYP3A4 in a concentration-dependent manner. Concomitant consumption of green tea with CYP3A4 substrates could increase the possibility of interactions, and this requires further clarification. The inhibition of CYP3A4 is not only due to the presence of catechin derivatives but methylxanthines may also contribute to this effect.

Antioxidant Activity and Antiproliferative Effects of Lycium barbarum's (Goji berry) Fractions on Breast Cancer Cell Lines.

BACKGROUND: Lycium barbarum has gained immense popularity over the past decade because of its antioxidant properties. There are many reports of observed health benefits of juice consumption, including prophylaxis in neoplastic disease and treatment of tumors. MATERIALS AND METHODS: In this study, we isolated three fractions of Lycium barbarum fruits - total water, pectin-free and polysaccharide, and determined their antioxidant activity by ORAC and HORAC assays. We investigated the antiproliferative effects of Lycium barbarum's pectin-free and polysaccharide fraction on three different breast cell lines - MCF-10A (non-tumorigenic epithelial breast cell line), MCF-7 (breast cancer cell line, estrogen, progesterone receptors +, HER2-), and MDA-MB-231 (breast cancer cell line, triple negative), by the MTT dye reduction assay. RESULTS: The Lycium barbarum's pectin-free fraction showed concentration-dependent growth inhibition on the three cell lines, moreover, on cancer cells (MCF- 7 and MDA-MB-231) it was significantly more pronounced. The polysaccharide fraction showed negligible activity on the three cell lines, only the highest concentration (1000 µg/mL), suppressed the proliferation of MCF-7 cells. The combination of pectin-free and polysaccharide fraction on MCF-7 did not show the expected synergistic effect. CONCLUSION: We found a relative correlation between the polyphenolic content of the extracts and the observed effects. The pectin-free extract had the highest content of polyphenols with the best antioxidant and antineoplastic activity against breast cancer cells. Addition of polysaccharide to the pectin-free fraction contributes to its pharmacological activity.

RIPK3 expression as a potential predictive and prognostic marker in metastatic colon cancer.

BACKGROUND: Colorectal cancer is one of the primary causes of cancer-related deaths and 5-fluorouracil (5-FU) therapy remains the cornerstone of treatment in these patients. Resistance to 5-FU represents a major obstacle; therefore, finding new predictive and prognostic markers is crucial for improvement of patient outcomes. Recently a new type of programmed cell death was discovered-necroptosis, which depends on receptor interacting protein 3 (RIPK3). Preclinical data showed that necroptotic cell death is an important effector mechanism of 5-FU-mediated anticancer activity. PURPOSE: To investigate the predictive and prognostic performance of RIPK3 expression in primary tumors. METHODS: Colon cancer patients (n=74) with metastatic stage were included in this retrospective study and all were treated with first-line 5-FU based chemotherapy. Immunohistochemical staining was performed. RESULTS: The progression free survival for the low expression group of RIPK3 was 5.6 months (95% CI, 4.4-6.8) vs 8.4 months (95% CI, 6.4-10.3) of the group with high expression (p=0.02). Moreover, patients with high expression of RIPK3 were associated with lower risk of disease progression HR 0.61 (95% CI, 0.38-0.97; p=0.044). Patients with high expression levels of RIPK3 also had significantly longer mean overall survival (OS) of 29.3 months (95% CI, 20.8-37.8) as compared with those with low expression: 18.5 months (95% CI, 15.06-21.9) (p= 0.036). In addition, univariate analysis showed that high level of RIPK3 expression was associated with a longer OS HR 0.59 (95% CI, 0.35-0.98; p=0.044). CONCLUSIONS: This study suggests that expression of RIPK3 in primary tumors of metastatic colon cancer patients should be further investigated for its potential as a promising predictive and prognostic marker.

Erucylphospho-N,N,N-trimethylpropylammonium (erufosine) is a potential antimyeloma drug devoid of myelotoxicity.

PURPOSE: Erufosine is an i.v. injectable alkylphosphocholine which is active against various haematological malignancies in vitro. In the present study, its effects on multiple myeloma (MM) cell lines and on murine and human hematopoietic progenitor cells (HPCs) were investigated. METHODS: The following MM cell lines were used: RPMI-8226, U-266 and OPM-2. The cytotoxicity of erufosine against these cell lines was determined by the MTT-dye reduction assay. Bcl-2, Bcl-X(L) and pAkt expression levels, activation of caspases, as well as cleavage of PARP, were studied by Western blotting. Migration was evaluated by a modified Boyden-chamber assay. The haematologic toxicity of erufosine was assessed using clonogenicity assays with normal HPCs of murine or human origin. RESULTS: Significant cytotoxic activity of erufosine against the MM cell lines was found. Comparison of the characteristics of erufosine-induced cell death in the three cell lines revealed a complex mode of action with apoptotic mechanisms prevailing in OPM-2 cells and non-apoptotic mechanisms prevailing in U-266 cells. The sensitivity of the MM cell lines to erufosine-induced apoptosis correlated inversely with the Bcl-X(L) expression level. Erufosine participated in synergistic interactions with various drugs. Furthermore, it showed potent migration-inhibiting activity in RPMI-8226 cells. Erufosine was not toxic to normal HPCs of murine or human origin and even stimulated progenitors from human umbilical cord blood to form granulocyte/macrophage colonies. Moreover, erufosine ameliorated the toxicity of bendamustine to murine HPCs. CONCLUSIONS: Overall, the data presented reveal that erufosine could have potential as an antimyeloma drug and deserves further development.