Polymorphisms in the VKORC1 gene are strongly associated with warfarin dosage requirements in patients receiving anticoagulation

Background

Warfarin is a mainstay of therapy for conditions associated with an increased risk of thromboembolic events. However, the use of this common agent is fraught with complications and little is known regarding inter‐individual variation in warfarin response.

Objective

We tested for association between single nucleotide polymorphisms (SNPs) in VKORC1 and CYP2C9 and average weekly warfarin dose required to maintain patients at their desired anticoagulation target.

Methods

The sample consisted of 93 European‐American patients from anticoagulation clinics at the University of North Carolina at Chapel Hill. Data on mean weekly warfarin dose were collected over a mean treatment period of 20.6 months. ANCOVA models were used and haplotype analysis was performed.

Results

Three of six VKORC1 SNPs were found to be very strongly associated with the average warfarin dose required to achieve the target international normalised ratio (INR; p<0.0001). The mean weekly dose by genotype ranged from approximately 27 to 47 mg. There was no evidence for an association between either of the two CYP2C9 polymorphisms studied, CYP2C9*2 and CYP2C9*3. CYP2C9*3 was significantly (p = 0.05) associated with average warfarin dosage after adjustment for VKORC1*1173.

Conclusions

These results are of considerable clinical interest and confirm recently published results regarding the role of these two genes in modifying warfarin metabolism and maintenance dosage. The consistent findings regarding the role of VKORC1 and CYP2C9 in warfarin metabolism and maintenance dosage represent a clinically useful proof of principal for the use of pharmacogenomic information in medicine and may lead to improved understanding of warfarin''s actions.     

Pharmacogenetics of glucocorticoid replacement could optimize the treatment of congenital adrenal hyperplasia due to 21-hydroxylase deficiency

INTRODUCTION:

21-hydroxylase deficiency is an autosomal recessive disorder that causes glucocorticoid deficiency and increased androgen production. Treatment is based on glucocorticoid replacement; however, interindividual variability in the glucocorticoid dose required to achieve adequate hormonal control has been observed.

OBJECTIVE:

The present study aimed to evaluate the association between polymorphic variants involved in glucocorticoid action and/or metabolism and the mean daily glucocorticoid dose in 21-hydroxylase deficiency patients.

METHODS:

We evaluated 53 patients with classical forms of 21-hydroxylase deficiency who were receiving cortisone acetate. All patients were between four and six years of age and had normal androgen levels.

RESULTS:

The P450 oxidoreductase A503V, HSD11B1 rs12086634, and CYP3A7*1C variants were found in 19%, 11.3% and 3.8% of the patients, respectively. The mean±SD glucocorticoid dose in patients with the CYP3A7*1C and wild-type alleles was 13.9±0.8 and 19.5±3.2 mg/m²/d, respectively. We did not identify an association between the P450 oxidoreductase or HSD11B1 allelic variants and the mean glucocorticoid dose.

CONCLUSION:

Patients carrying the CYP3A7*1C variant required a significantly lower mean glucocorticoid dose. Indeed, the CYP3A7*1C allele accounted for 20% of the variability in the cortisone acetate dose. The analysis of genes involved in glucocorticoid metabolism may be useful in the optimization of treatment of 21-hydroxylase deficiency.     

Drug-drug interation prediction between ketoconazole and anti-liver cancer drug Gomisin G

Background

Gomisin G, isolated from herb Schisandra chinensis, exhibits anti-tumor activities. Therefore, Gomisin G is a drug candidate for anti-liver cancer therapy.

Aims

To predict the metabolic behavior and metabolism-based drug-drug interaction of gomisin G.

Methods

Molecular docking method was used. The crystal structure of CYP3A4 with the ligand ketoconazole was chosen from protein data bank (http://www.rcsb.org/pdb). Chemdraw software was used to draw the two-dimensional structure of gomisin G with standard bond lengths and angles.

Results

Gomisin G can be well docked into the activity site of CYP3A4, and distance between gomisin G the heme active site was 2.75 Å. To evaluate whether the inhibitors of CYP3A4 can affect the metabolism of gomisin G, co-docking of gomisin G and ketoconazole was further performed. The distance between ketoconazole and activity center (2.10 Å) is closer than the distance between gomisin G and activity center of CYP3A4, indicating the easy influence of CYP3A4''s strong inhibitor towards the metabolism of gomisin G.

Conclusion

Gomisin G is a good substrate of CYP3A4, and CYP3A4 inhibitors easily affect the metabolism of Gomisin G.     

Frequency of genetic polymorphisms of PXR gene in the Brazilian population

INTRODUCTION:

PXR polymorphisms have been implicated in modulating CYP3A4 and PXR expression, potentially accounting for interindividual differences in drug metabolism. The prevalence of PXR polymorphisms varies among ethnic groups and data on the allelic distribution in the highly mixed Brazilian population is lacking. The aim of this study was to analyze genetic variations in the PXR gene in Brazilians and to compare the results to other ethnic groups.

METHODS:

DNA samples from 117 healthy Brazilians underwent PCR amplification and sequencing.

RESULTS:

Eleven polymorphisms were identified, 3 of which are highly associated with differences in CYP3A4 expression. We also identified 1 new synonymous variant in 1.3% of the alleles. Among the functional polymorphisms, –25913 C>T and –6994T>C occurred at a higher frequency compared to the African alleles (p < 0.05) but at a lower frequency compared to Caucasian alleles. The 8055 C>T allele was found at a similar frequency to those described in Caucasians and Africans (p > 0.05).

CONCLUSION:

We observed that functional variants of the PXR were frequent in our sample of the Brazilian population. Our results suggest that PXR gene variants may be of interest in pharmacogenetic studies involving Brazilians.     

Effects of heme precursors on CYP1A2 and POR expression in the baculovirus/Spodoptera frugiperda system

Objective

CYP1A2 and NADPH-CYP450 oxidoreductase (POR) were expressed in the baculovirus/Spodoptera frugiperda (sf9) system. The aim of this study was to investigate the effects of heme precursors on the expression of CYP1A2 and POR.

Methods

The heme precursors [δ-Aminolaevulinic Acid (5-ALA), Fe³⁺ and hemin] were introduced into the system to evaluate their effects on the expression of CYP1A2, POR and their co-expression. All the proteins were identified using immunoblotting, CO-difference spectroscopy, or cytochrome c assay.

Results

In the present study, functional CYP1A2 and POR were successfully expressed in the baculovirus/sf9 system, and both of them showed high activities. Co-addition of 5-ALA and Fe³⁺ significantly improved expression of CYP1A2 by about 50% compared with the addition of 5-ALA, Fe³⁺ or hemin alone. Either co-addition of 5-ALA and Fe³⁺ or addition of 5-ALA or Fe³⁺ alone improved the POR expression level 2 fold and its activity 7-10 fold compared with control (no addition). However, unlike CYP1A2, there was no difference between the co-addition and addition of these heme precursors alone. Different ratios of BvCYP1A2 to BvPOR also affected the co-expression of CYP1A2 and POR, with a 3:1 ratio of BvCYP1A2 / BvPOR significantly increasing their co-expression. Surprisingly, the addition of 0.1 mM 5-ALA or Fe³⁺ alone, but not their co-addition, could significantly improve the CYP1A2 and POR co-expression (P < 0.05).

Conclusion

5-ALA and Fe³⁺ increased the expression of CYP1A2 and POR in a baculovirus/sf9 system, but the pattern of their expression was different between their expression alone and co-expression.     

The Inhibitory Activity of the Extracts of Popular Medicinal Herbs on CYP1A2, 2C9, 2C19 and 3A4 and the Implications for Herb-Drug Interaction

Background

Studies have suggested an increasing practice of concurrent herb-drug consumption. One of the major clinical risks of such concomitant herb-drug use is pharmacokinetic herb-drug interaction (HDI). This is brought about by the ability of phytochemicals to inhibit or induce the activity of metabolic enzymes. The aim of this study was to investigate the potential of the crude aqueous extracts of three popular medicinal herbs used in South Africa to inhibit major cytochrome P450 (CYP) enzymes.

Materials and Methods

The extracts of Bowiea volubilis, Spirostachys africana and Tulbaghia violacea were incubated with human liver microsomes (HLM) to monitor the phenacetin O-deethylation, diclofenac 4′-hydroxylation, S-mephenytoin 4′-hydroxylation and testosterone 6β-hydroxylation as respective probe reactions for CYP1A2, CYP2C9, CYP2C19 and CYP3A4. The inhibitory activity, where observed, was profiled against the extract concentration.

Results

Extracts of Bowiea volubilis inhibited the metabolic activity of CYP1A2 and CYP3A4 with IC₅₀ values of 92.3 ± 5.5 µg/mL and 8.1 ± 0.6 µg/mL respectively. Similar observation with Spirostachys africana showed inhibitory activity against CYP1A2 and CYP3A4 with respective IC₅₀ values of 14.3 ± 0.6 µg/mL and 47.4 ± 2.4 µg/mL. Tulbaghia violacea demonstrated relatively weak inhibitory activity against CYP1A2 (767.4 ± 10.8 µg/mL) and CYP2C9 (921 ± 15.3 µg/mL).

Conclusion

The results suggest the potential for HDI between the herbs and the substrates of the affected enzymes, if sufficient in vivo concentration is attained.     

Antiplatelet Effect of Clopidogrel Can Be Reduced by Calcium-Channel Blockers

Purpose

Clopidogrel is metabolized by the hepatic cytochrome P450 (CYP) system into its active thiol metabolite. CYP3A4 is involved in the metabolism of both clopidogrel and dihydropyridine calcium channel blockers (CCBs). A few reports have suggested an inhibitory interaction between CCBs and clopidogrel. Accordingly, the aim of this study was to determine the effect of CCBs on the antiplatelet activity of clopidogrel by serial P2Y12 reaction unit (PRU) measurements.

Materials and Methods

We assessed changes in antiplatelet activity in patients receiving both clopidogrel and CCBs for at least 2 months prior to enrollment in the study. The antiplatelet activity of clopidogrel was measured by VerifyNow P2Y12 assay in the same patient while medicated with CCBs and at 8 weeks after discontinuation of CCBs. After discontinuation of the CCBs, angiotensin receptor blockers were newly administered to the patients or dosed up for control of blood pressure.

Results

Thirty patients finished this study. PRU significantly decreased after discontinuation of CCBs (238.1±74.1 vs. 215.0±69.3; p=0.001). Of the 11 patients with high post-treatment platelet reactivity to clopidogrel (PRU≥275), PRU decreased in nine patients, decreasing below the cut-off value in seven of these nine patients after 8 weeks. Decrease in PRU was not related to CYP2C19 genotype.

Conclusion

CCBs inhibit the antiplatelet activity of clopidogrel.     

In vitro evidence of baicalein's inhibition of the metabolism of zidovudine (AZT)

Background

Herb-drug interaction (HDI) has been regarded as a key factor limiting the clinical application of herbs and drugs.

Aims

Potential baicalein-zidovudine (AZT) interaction was predicted in the present study.

Methods

In vitro evaluation of baicalein''s inhibition towards human liver microsomes (HLMs)-catalyzed metabolism of zidovudine (AZT) was performed. Dixon and Lineweaver-Burk plots were used to determine the inhibition kinetic type, and second plot with the slopes from Lineweaver-Burk plot versus the concentrations of baicalein was employed to calculate the inhibition parameter (Ki). In combination with the in vivo concentration of baicalein, in vitro-in vivo extrapolation (IVIVE) was carried out to predict in vivo baicalein-AZT interaction.

Results

Competitive inhibition of baicalein towards AZT metabolism was demonstrated, and the K_i value was calculated to be 101.2 µM. The value of AUCi/AUC was calculated to be 2.

Conclusion

Potential baicalein-AZT interaction was indicated in the present study, indicating the need for monitoring when AZT is co-administrated with baicalein or baicalein-containing herbs.     

Association of CYP2C19*2 and *3 Genetic Variants with Essential Hypertension in Koreans

Purpose

The cytochrome P450 2C19 (CYP2C19) metabolizes arachidonic acid to produce epoxyicosanoid acids, which are involved in vascular tone and regulation of blood pressure. Recent findings suggest that CYP2C19 gene might be considered as a novel candidate gene for treatment of cardiovascular disease. The aim of the present study was to evaluate the association between two variants, CYP2C19^*2 (681G>A) and CYP2C19^*3 (636G>A) and the development of essential hypertension (EH) in Koreans.

Materials and Methods

We carried out an association study in a total of 1190 individuals (527 hypertensive subjects and 663 unrelated healthy controls). The CYP2C19 polymorphisms were genotyped using the SNaPShot™ assay.

Results

The distribution of alleles and genotypes of CYP2C19^*3 showed significant difference between hypertensive patients and normal controls (p=0.011 and p=0.013, respectively). Logistic regression analysis indicated that the CYP2C19^*3 (636A) allele carriers were significantly associated with EH [odds ratio, 0.691; 95% confidence interval (CI), 0.512-0.932, p=0.016], in comparison to wild type homozygotes (CYP2C19^*1/^*1). Neither genotype nor allele distribution of CYP2C19^*2 polymorphism showed significant differences between hypertensive and control groups (p>0.05).

Conclusion

Our present findings strengthen the evidence of an association between CYP2C19 gene polymorphism and EH prevalence. In particular, the CYP2C19^*3 defective allele may contribute to reduced risk for the development of EH.     

Use of Drugs that Act on the Cytochrome P450 System in the Elderly

OBJECTIVES:

The objective of this study was to analyze medications that act on the cytochrome P450 (CYP450) enzymatic system and are used daily by non-institutionalized elderly individuals.

METHODS:

A cross-sectional population-based study of elderly individuals (≥ 60 years old) was conducted. All continuously used medications with hepatic metabolism via CYP450 that are classified as substrates, inducers or inhibitors were considered. For the analysis, elderly individuals were stratified according to age groups, and hepatic metabolism activity due to daily alcohol consumption and smoking were considered.

RESULTS:

Elderly individuals (396 in total: 222 women and 174 men) between 60 and 95 years of age (mean: 72.1) were assessed. Use of drugs that act on CYP450 was identified in 61.6% of the subjects. Drug use was observed among 16.2% of the subjects: three drugs among 9.8% and four or more among 6.3% of the subjects. The metabolic activities of the drugs used were classified as substrates (58.8%), inhibitors (14.9%), and inducers (4.3%). The main drugs used were beta-blockers and statins (as substrates), proton pump inhibitors and fluoxetine (as inhibitors), and prednisone and carbamazepine (as inducers).

CONCLUSIONS:

The results demonstrate that the elderly use high levels of medications that act on CYP450, thereby increasing the risk of drug interactions in a group that is already vulnerable to adverse drug effects.     

Genotoxicity and cytotoxicity of sevoflurane in two human cell lines in vitro with ionizing radiation

Objective:

To determine the in vitro toxicity of different concentrations of sevoflurane in cells exposed to X-ray.

Methods:

The genotoxic effects of sevofluorane were studied by means of the micronucleus test in cytokinesis-blocked cells of irradiated human lymphocytes. Subsequently, its cytotoxic effects on PNT2 (normal prostate) cells was determined using the cell viability test (MTT) and compared with those induced by different doses of X-rays.

Results:

A dose- and time-dependent cytotoxic effect of sevofluorane on PNT2 cells was determined (p >0.001) and a dose-dependent genotoxic effect of sevofluorane was established (p >0.001). Hovewer, at volumes lower than 30 μL of sevofluorane at 100%, a non-toxic effect on PNT2 cells was shown.

Conclusion:

Sevofluorane demonstrates a genotoxic capacity as determined in vitro by micronucleus test in cytokinesis-blocked cells of irradiated human lymphocytes.     

CYP17 T27C polymorphism and prostate cancer risk: a meta-analysis based on 31 studies

Objective

The cytochrome P450 17α-hydroxylase (CYP17) plays a vital role in androgen biosynthesis. A T-to-C polymorphism in the 5′ promoter region of CYP17 has been implicated as a risk factor for prostate cancer, but the results of individual studies are inconclusive or controversial. To derive a more precise estimation of the relationship, we performed an updated meta-analysis from 31 studies based on 27 publications.

Methods

A comprehensive search was conducted to examine all the eligible studies of CYP17 polymorphism and prostate cancer risk. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association.

Results

Overall, individuals with CC/CT genotype were not associated with prostate cancer risk (CC vs. TT: OR = 1.03, 95% CI = 0.86-1.24, P = 0.72, P_{heterogeneity} < 0.0001; CT vs. TT: OR = 0.99, 95% CI = 0.87-1.12, P = 0.88, P_{heterogeneity} = 0.0006). In the stratified analysis by ethnicity, there was a significantly increased risk of prostate cancer among individuals of African descent under the recessive model (OR = 1.56, 95% CI = 1.01-2.39, P = 0.04, P_{heterogeneity} = 0.65).

Conclusion

This meta-analysis suggested that CYP17 polymorphism might be associated with prostate cancer risk among individuals of African descent.     

Comparison of two peptide radiotracers for prostate carcinoma targeting

OBJECTIVES:

Scintigraphy is generally not the first choice treatment for prostate cancer, although successful studies using bombesin analog radiopeptides have been performed. Recently, a novel peptide obtained using a phage display library demonstrated an affinity for prostate tumor cells. The aim of this study was to compare the use of a bombesin analog to that of a phage display library peptide (DUP-1) radiolabeled with technetium-99m for the treatment of prostate carcinoma. The peptides were first conjugated to S-acetyl-MAG3 with a 6-carbon spacer, namely aminohexanoic acid.

METHODS:

The technetium-99m labeling required a sodium tartrate buffer. Radiochemical evaluation was performed using ITLC and was confirmed by high-performance liquid chromatography. The coefficient partition was determined, and in vitro studies were performed using human prostate tumor cells. Biodistribution was evaluated in healthy animals at various time points and also in mice bearing tumors.

RESULTS:

The radiochemical purity of both radiotracers was greater than 95%. The DUP-1 tracer was more hydrophilic (log P = -2.41) than the bombesin tracer (log P = -0.39). The biodistribution evaluation confirmed this hydrophilicity by revealing the greater kidney uptake of DUP-1. The bombesin concentration in the pancreas was greater than that of DUP-1 due to specific gastrin-releasing peptide receptors. Bombesin internalization occurred for 78.32% of the total binding in tumor cells. The DUP-1 tracer showed very low binding to tumor cells during the in vitro evaluation, although tumor uptake for both tracers was similar. The tumors were primarily blocked by DUP-1 and the bombesin radiotracer primarily targeted the pancreas.

CONCLUSION:

Further studies with the radiolabeled DUP-1 peptide are recommended. With further structural changes, this molecule could become an efficient alternative tracer for prostate tumor diagnosis.     

Probe substrate and enzyme source-dependent inhibition of UDP-glucuronosyltransferase (UGT) 1A9 by wogonin

Background

Drug-metabolizing enzymes (DMEs) inhibition based drug-drug interaction and herb-drug interaction severely challenge the R&D process of drugs or herbal ingredients.

Objective

To evaluate the inhibition potential of wogonin (an important flavonoid isolated from the root of Scutellaria baicalensis) towards one of the most important phase II DMEs, UDP-glucuronosyltransferase (UGT) 1A9.

Methods

Both recombinant UGT1A9-catalyzed 4-methylumbelliferone (4-MU) glucuronidation reaction and human liver microsomes (HLMs)-catalyzed propofol glucuronidation reaction were used as two different probe reactions.

Results

Wogonin noncompetitively inhibited recombinant UGT1A9-catalyzed 4-MU glucuronidation, and exerted competitive inhibition towards HLMs-catalyzed propofol glucuronidation. The inhibition kinetic parameters (K_i) were calculated to be 3.2 µM and 52.0µM, respectively.

Conclusion

Necessary monitoring was needed when wogonin was co-administered with the clinical drugs mainly undergoing UGT1A9-mediated glucuronidation elimination. Additionally, probe reactions-dependent inhibition of wogonin towards the activity of UGT1A9 should be paid attention when translating these in vitro data into in vivo situation.     

In vitro evidence of possible influence of scutellarein towards bile acids' metabolism

Background

The glucuronidation process has been regarded as the key elimination process for toxic bile acids. UDP-glucuronosyltransferase (UGT) 1A3 is one important metabolizing enzyme involved in this process.

Objective

To evaluate the inhibition of UGT1A3 by scutellarein which is an important herbal ingredient using in vitro method, trying to indicate the possibility of toxicity due to the accumulation of toxic bile acids.

Methods

Due to the difficulty to gain the standards of biles acids'' glucuronides, the recombinant UGT1A3-catalyzed 4-methylumbelliferone (4-MU) glucuronidation reaction was employed to profile the activity of UGT1A3.

Results

The results showed that scutellarein inhibited UGT1A3 in a concentration-dependent behaviour. Competitive inhibition was demonstrated using both Dixon plot and Lineweaver-Burk plot, and the inhibition kinetic parameter (K_i) was calculated to be 5.8uM.

Conclusion

All these data reminded the necessary monitoring of the levels of bile acids in plasma when utilizing scutellarein and the herbs containing this compound.     

Protective effects of total glucosides of paeony and the underlying mechanisms in carbon tetrachloride-induced experimental liver injury

Introduction

We explored the protective effects of total glucosides of paeony (TGP) and the underlying mechanisms in carbon tetrachloride (CCl₄)-induced experimental liver injury in mice.

Material and methods

Chronic liver damage was induced by intraperitoneal injection of CCl₄ (0.5 µl/g) three times per week for 8 weeks. Mice also received 25, 50 or 100 mg/kg TGP. Liver sections were stained with haematoxylin/eosin. Serum amino transferases, lipid peroxidation and tumour necrosis factor-α (TNF-α) levels were determined using commercial assays. Quantitative real-time polymerase chain reaction was used to determine the changes in hepatic TNF-α, COX-2, iNOS and HO-1 expression. Protein levels of nitric oxide synthase, cyclooxygenase-2, haem oxygenase-1 and cytochrome P450 2E1 were determined by western blotting.

Results

Histological results showed that TGP improved the CCl₄-induced changes in liver structure and alleviated lobular necrosis. The increases in serum protein and hepatic mRNA expression of TNF-α induced by CCl₄ treatment were suppressed by TGP. Total glucosides of paeony also attenuated the increase the expression in iNOS and CYP2E1 but augmented the increase in HO-1.The mRNA and protein expression levels of inducible HO-1 increased significantly after CCl₄ treatment.

Conclusions

Total glucosides of paeony protects hepatocytes from oxidative damage induced by CCl₄. Total glucosides of paeony may achieve these effects by enhancing HO-1 expression and inhibiting the expression of proinflammatory mediators.     

In vitro evidence for bakuchiol's influence towards drug metabolism through inhibition of UDP-glucuronosyltransferase (UGT) 2B7

Background

Inhibition of drug-metabolizing enzymes (DMEs) has been regarded as one of the most important reason for clinical drug-drug interaction.

Aim

The aim of the present study is to evaluate the inhibition of bakuchiol towards UDP-glucuronosyltransferase (UGT) 2B isoforms.

Methods

In vitro recombinant UGT2B-catalyzed 4-methylumbelliferone glucuronidation was used as the probe reaction. Dixon plot and Lineweaver-Burk plot were employed to determine the inhibition kinetic type, and nonlinear regression of data was utilized to calculate the inhibition kinetic parameter (Ki). In vitro-in vivo extrapolation (IVIVE) was carried out to predict in vivo inhibition magnitude.

Results

Among the tested UGT2B isoforms, UGT2B7 was inhibited by the strongest intensity. The noncompetitive inhibition was demonstrated by the results obtained from Dixon plot and Lineweaver-Burk plot. The K_i value was calculated to be 10.7 µM. In combination with the reported concentration after an intravenous administration of bakuchiol (15 mg/kg) in rats, the high risk of in vivo inhibition of bakuchiol towards UGT2B7-catalyzed metabolism of drugs was indicated.

Conclusion

All these results provide an important information for the risk evaluation of the clinical utilization of bakuchiol.     

In vitro-in vivo Pharmacokinetic correlation model for quality assurance of antiretroviral drugs

Introduction:

The in vitro-in vivo pharmacokinetic correlation models (IVIVC) are a fundamental part of the drug discovery and development process. The ability to accurately predict the in vivo pharmacokinetic profile of a drug based on in vitro observations can have several applications during a successful development process.

Objective:

To develop a comprehensive model to predict the in vivo absorption of antiretroviral drugs based on permeability studies, in vitro and in vivo solubility and demonstrate its correlation with the pharmacokinetic profile in humans.

Methods:

Analytical tools to test the biopharmaceutical properties of stavudine, lamivudine y zidovudine were developed. The kinetics of dissolution, permeability in caco-2 cells and pharmacokinetics of absorption in rabbits and healthy volunteers were evaluated.

Results:

The cumulative areas under the curve (AUC) obtained in the permeability study with Caco-2 cells, the dissolution study and the pharmacokinetics in rabbits correlated with the cumulative AUC values in humans. These results demonstrated a direct relation between in vitro data and absorption, both in humans and in the in vivo model.

Conclusions:

The analytical methods and procedures applied to the development of an IVIVC model showed a strong correlation among themselves. These IVIVC models are proposed as alternative and cost/effective methods to evaluate the biopharmaceutical properties that determine the bioavailability of a drug and their application includes the development process, quality assurance, bioequivalence studies and pharmacosurveillance.     

Preventive effects of green tea (Camellia sinensis var. assamica) on diabetic nephropathy

Purpose

This study aimed to evaluate the preventive effects of Camellia sinensis var. assamica (CSVA) on diabetic nephropathy in in vitro and in vivo models.

Materials and Methods

MDCK cells were incubated with 1 mM of oxalate with or without different concentrations of CSVA, then MTT and malondialdehyde (MDA) assays were performed to investigate the preventive effects of CSVA on oxalate-induced cytotoxicity and oxidative stress. Thirty male db/db mice were divided into three groups. Group 1 were fed AIN-93G ad libitum; group 2 were fed AIN-93G mixed with 10% fermented CSVA ad libitum; group 3 were fed AIN-93G mixed with 10% non-fermented CSVA ad libitum. The mice were sacrificed 14 weeks later, and the serum glucose level, 24-hour urine chemistry, and morphological changes in the kidneys were examined.

Results

As CSVA concentrations increased, viable MDCK cells increased in concentration. MDA production decreased over time in the CSVA treated group. The creatinine clearance of group 3 was lower than those of groups 1 and 2. The amount of urine microalbumin and protein in group 1 were higher than those in groups 2 and 3. Also, more glomerulus basement membrane foot processes were preserved in groups 2 and 3.

Conclusion

In conclusion, CSVA has beneficial preventive tendencies towards diabetic nephropathy in both in vitro and in vivo models.