Effects of Diabetes Mellitus on the Disposition of Tofacitinib, a Janus Kinase Inhibitor, in Rats

Tofacitinib, a Janus kinase inhibitor, was developed for the treatment of rheumatoid arthritis. Recently, it has been associated with an increased change in arthritis development in patients with diabetes. Herein, we evaluated the pharmacokinetics of tofacitinib after intravenous (10 mg/kg) and oral (20 mg/kg) administration to rats with streptozotocin-induced diabetes mellitus and control rats. Following intravenous administration of tofacitinib to rats with streptozotocin-induced diabetes mellitus, area under the plasma concentration-time curve from time zero to infinity of tofacitinib was significantly smaller (33.6%) than that of control rats. This might be due to the faster hepatic intrinsic clearance (112%) caused by an increase in the hepatic cytochrome P450 (CYP) 3A1(23) and the faster hepatic blood flow rate in rats with streptozotocin-induced diabetes mellitus than in control rats. Following oral administration, area under the plasma concentration-time curve from time zero to infinity of tofacitinib was also significantly smaller (55.5%) in rats with streptozotocin-induced diabetes mellitus than that in control rats. This might be due to decreased absorption caused by the higher expression of P-glycoprotein and the faster intestinal metabolism caused by the higher expression of intestinal CYP3A1(23), which resulted in the decreased bioavailability of tofacitinib (33.0%) in rats with streptozotocin-induced diabetes mellitus. In summary, our findings indicate that diabetes mellitus affects the absorption and metabolism of tofacitinib, causing faster metabolism and decreased intestinal absorption in rats with streptozotocin-induced diabetes mellitus.

Extended Intake of Mulberry Leaf Extract Delayed Metformin Elimination via Inhibiting the Organic Cation Transporter 2

Diabetes mellitus (DM) has become a major health problem in most countries of the world. DM causes many complications, including hyperglycemia, diabetic ketoacidosis, and death. In Asia, mulberry has been used widely in the treatment of DM. Combination of drugs with herbal medicine may reduce the unwanted side effects caused by drugs. In this study, the influence of extended mulberry leaves extract (MLE) intake on metformin (Met) was evaluated in terms of pharmacokinetics and pharmacodynamics in DM-induced rats. Three week-treatment of MLE alone produced the anti-hyperglycemic effect (around 24%) if compared to the control. Interestingly, Met administration after MLE treatment for 3 weeks enhanced about 49% of the anti-hyperglycemic effect of Met. In addition, the extended intake of MLE potentiated the anti-hyperglycemic effect of Met on various concentrations. This potentiated anti-hyperglycemic effect of Met appears to be due to the pharmacokinetic change of Met. In this study, 3 week-treatment of MLE reduced the elimination of Met in DM-induced rats. In addition, MLE reduced the human organic cation transporter 2 (hOCT2) activity in a concentration-dependent manner. Thus, these findings suggest that MLE lowered the elimination of Met via inhibiting the hOCT2.

Influence of Plantago ovata husk (dietary fiber) on the bioavailability and other pharmacokinetic parameters of metformin in diabetic rabbits

Background

Metformin is an oral hypoglycemic agent frequently used in patients with type 2 diabetes. In this study, we have investigated the influence of the dietary fiber Plantago ovata husk on the pharmacokinetics of this drug when included in the diet, as well as when administered at the same time as metformin.

Methods

Six groups of 6 rabbits were used. Groups 1 to 3 were fed with standard chow and groups 4 to 6 with chow supplemented with fiber (3.5 mg/kg/day). Groups 1 and 4 received metformin intravenously (30 mg/kg). Groups 2 and 5 received metfomin orally (30 mg/kg), and number 3 and 6 were treated orally with metformin (30 mg/kg) and fiber (300 mg/kg).

Results

The changes caused by the inclusion of fiber in the feeding were more important in groups that received oral metformin. In this way, metformin oral bioavailability showed an increase of 34.42% when rabbits were fed with supplemented chow.

Conclusions

Plantago ovata husk increased the amount of absorbed metformin when included in the diet (significant increase in AUC), and delayed its absorption when administered at the same time (significant increase in t_max).

Lack of Effects of Metformin and AICAR Chronic Infusion on the Development of Hypertension in Dahl Salt-Sensitive Rats

In the kidney, reabsorption via the epithelial sodium channel (ENaC) is involved in long-term blood pressure control. Previously we demonstrated that ENaC hyperactivity is associated with development of salt-sensitive (SS) hypertension in Dahl SS rats. AMP-activated kinase (AMPK), playing a role in cellular energy homeostasis, has been shown to decrease ENaC activity. Here, we tested whether metformin and AICAR, two drugs that activate AMPK, affect the development of salt-induced hypertension. High salt diet significantly increased mean arterial pressure (MAP) in Dahl SS rats. Blood pressure elevation was accompanied by a short-term decline of heart rate and increased circadian arterial pressure dipping. Metformin and AICAR were delivered intravenously at doses of 200 and 20 mg/kg/day, respectively. However, both control and drug-treated groups had similar development of high blood pressure within 3 weeks of 8% NaCl dietary salt intake. In the metformin-treated animals MAP reached 164.9 ± 9.1 mmHg, which was not significantly different from the control group (171.8 ± 5.6 mmHg). Patch clamp analysis revealed that the metformin-treated rats had no difference in the activity of ENaC. AICAR treatment also did not affect the development of hypertension and kidney injury. MAP reached 182.8 ± 4.8 and 178.0 ± 2.8 mmHg in AICAR and vehicle treated groups, respectively. Of note, we found that high-salt diet activated AMPK in the Dahl SS rats, and treatment with these AMPK activators had no significant further effect on AMPK activity. We conclude that AMPK activators, at least under these conditions, do not affect development of hypertension during high-salt diet in the Dahl SS rat model.

Pharmacokinetics of metformin in the rat: assessment of the effect of hyperlipidemia and evidence for its metabolism to guanylurea

Metformin pharmacokinetics are highly dependent upon organic cationic transporters. There is evidence of a change in its renal clearance in hyperlipidemic obese patients, and no information on its metabolic fate. To study some of these aspects, the influence of poloxamer 407 (P407)-induced hyperlipidemia on metformin pharmacokinetics was assessed. Control and P407-treated adult male rats were administered 30 mg/kg metformin intravenously (i.v.). The pharmacokinetic assessments were performed at 2 time points, 36 and 108 h, following the intraperitoneal dose of P407 (1 g/kg). mRNA and protein expressions of cationic drug transporters were also measured. There was no evidence of a change in metformin pharmacokinetics after i.v. doses as a consequence of short-term hyperlipidemia, and a change in transporter mRNA but not protein expression was observed in the P407- treated rats 108 h after P407 injection. Urinary recovery of unchanged drug was high (>90%) but incomplete. Presumed metabolite peaks were detected in chromatograms of hepatocytes and microsomal protein spiked with metformin. Comparative chromatographic elution times and mass spectra suggested that one of the predominant metabolites was guanylurea. Hyperlipidemia by itself did not affect the pharmacokinetics of metformin. Guanylurea is a putative metabolite of metformin in rats.

Comparative pharmacokinetics of arctigenin in normal and type 2 diabetic rats after oral and intravenous administration

Arctigenin is the main active ingredient of Fructus Arctii for the treatment of type 2 diabetes. In this study, the pharmacokinetics of arctigenin in normal and type 2 diabetic rats following oral and intravenous administration was investigated. As compared to normal rats, Cmax and AUC(0-10h) values of oral arctigenin in diabetic rats increased by 356.8% and 223.4%, respectively. In contrast, after intravenous injection, the Cmax and AUC(0-10h) values of arctigenin showed no significant difference between diabetic and normal rats. In order to explore how the bioavailability of oral arctigenin increased under diabetic condition, the absorption behavior of arctigenin was evaluated by in situ single-pass intestinal perfusion (SPIP). The results indicated that arctigenin was a substrate of P-glycoprotein (P-gp). The absorption difference of arctigenin in the normal and diabetic rats could be eliminated by the pretreatment of classic P-gp inhibitor verapamil, suggesting that P-gp might be the key factor causing the absorption enhancement of arctigenin in diabetic rats. Further studies revealed that the uptake of rhodamine 123 (Rho123) in diabetic rats was significantly higher, indicating that diabetes mellitus might impair P-gp function. Consistently, a lower mRNA level of P-gp in the intestine of diabetic rats was found. In conclusion, the absorption of arctigenin after oral administration was promoted in diabetic rats, which might be partially attribute to the decreased expression and impaired function of P-gp in intestines.

Validated LC-MS method for simultaneous quantitation of catalpol and harpagide in rat plasma: application to a comparative pharmacokinetic study in normal and diabetic rats after oral administration of Zeng-Ye-Decoction

A simple and efficient liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for simultaneous quantitation of catalpol and harpagide in normal and diabetic rat plasma. Protein precipitation extraction with acetonitrile was carried out using salidroside as the internal standard (IS). The LC separation was performed on an Elite C18 column (150 × 4.6 mm, 5 µm) with the mobile phase consisting of acetonitrile and water within a runtime of 12.0 min. The analytes were detected without endogenous interference in the selected ion monitoring mode with positive electrospray ionization. Calibration curves offered satisfactory linearity (r > 0.99) at linear range of 0.05-50.0 µg/mL for catalpol and 0.025-5.0 µg/mL for harpagide with the lower limits of quantitation of 0.05 and 0.025 µg/mL, respectively. Intra- and inter-day precisions (RSD) were <9.4%, and accuracy (RE) was in the -6.6 to 4.9% range. The extraction efficiencies of catalpol, harpagide and IS were all >76.5% and the matrix effects of the analytes ranged from 86.5 to 106.0%. The method was successfully applied to the pharmacokinetic study of catalpol and harpagide after oral administration of Zeng-Ye-Decoction to normal and diabetic rats, respectively.

Effects of Korean red ginseng extract on acute renal failure induced by gentamicin and pharmacokinetic changes by metformin in rats

AIM OF THE STUDY

Korean red ginseng is one of the best selling dietary supplements and its individual constituents enhance renal function. Acute renal failure (ARF) is a predisposing complication of diabetes mellitus as a result of combination drug therapy. The combination of antibiotic-antidiabetic drugs can entail toxicities and drug interactions because of the antibiotic resistance in patients with severe bacterial infection. Currently, gentamicin-metformin combination therapy is commonly prescribed for treating bacterial infections and diabetes, even though both drugs are mainly excreted via the kidney. Thus, this study was designed to investigate whether a Korean red ginseng extract (KRG) prevents renal impairment and pharmacokinetic changes by metformin in rats with renal failure induced by gentamicin.

MATERIALS AND METHODS

The in vivo pharmacokinetics and in vitro hepatic/intestinal metabolism of metformin were assessed using control (CON), control with Korean red ginseng extract (KRG-CON), acute renal failure induced by gentamicin (ARF), and ARF with Korean red ginseng (KRG-ARF) rats.

RESULTS AND CONCLUSIONS

Pharmacokinetic changes of metformin did not occur in KRG-ARF rats because KRG reduce the renal accumulation of gentamicin compared to ARF rats. Thus, KRG seemed to prevent acute renal failure induced by gentamicin treatment.

Reduced clearance of ε-acetamidocaproic acid in rats with acute renal failure induced by uranyl nitrate

Objectives

Anti-ulcer drugs are frequently used in patients with acute renal failure (ARF). Zinc acexamate is ionized to zinc and ε-acetamidocaproic acid and free EACA exerts a potent therapeutic effect in treating gastric or duodenal ulcers with few side effects. Thus, pharmacokinetic changes in rats with acute renal failure induced by uranyl nitrate (U-ARF rats) were investigated in this study.

Methods

The in-vivo pharmacokinetics and in-vitro hepatic/intestinal metabolism of EACA were assessed using control and U-ARF rats. The mechanism of urinary excretion of EACA was further investigated in rats.

Key findings

After intravenous and oral administration of zinc acexamate to U-ARF rats, there were significant increases in the values of the area under the curve (AUC) and decreases in the values for time-averaged renal and nonrenal clearances (Clr and Clnr, respectively) compared with control rats. Slower Clnr was partly due to a decrease in the metabolism in liver and/or intestine. Slower Clr could have been due to urine flow rate-dependent timed-interval renal clearance, decrease in organic anion transporter-mediated renal excretion (drug interaction with probenecid and decrease in the relative contribution of net secretion compared with glomerular filtration in U-ARF rats) and/or impaired kidney function.

Conclusions

The pharmacokinetics were significantly altered in U-ARF rats due to the changes in both the hepatic/intestinal metabolism and urinary excretion.

Combined contributions of impaired hepatic CYP2C11 and intestinal breast cancer resistance protein activities and expression to increased oral glibenclamide exposure in rats with streptozotocin-induced diabetes mellitus

The purpose of this study was to evaluate the contributions of impaired cytochrome P450 and breast cancer resistance protein (BCRP) activity and expression to drug pharmacokinetics under diabetic conditions. Diabetes was induced in rats with the intraperitoneal administration of streptozocin. Glibenclamide (GLB), a substrate of BCRP, served as a model drug. The pharmacokinetics of orally administered GLB (10 mg/kg) were studied. The results showed that diabetes mellitus significantly increased exposure (area under the curve and peak concentration) to GLB after oral administration. Data from hepatic microsomes suggested impairment of GLB metabolism in diabetic rats. GLB metabolism in hepatic microsomes was significantly inhibited by a selective inhibitor (sulfaphenazole) of CYP2C11 and an anti-CYP2C11 antibody. Western blotting further indicated the contribution of impaired CYP2C11 expression to the impairment of GLB metabolism. Excretion data showed that ∼72% of the orally administered dose was excreted in the feces of normal rats, which indicates an important role for intestinal BCRP. Diabetes significantly decreased the recovery from feces, which was only 40% of the orally administered dose. Results from in situ, single-pass, intestinal perfusion experiments revealed that diabetes significantly increased the apparent effective permeability and decreased the efflux of GLB through the intestine; this suggests impairment of intestinal BCRP function, which may play a role in the increased exposure to orally administered GLB in diabetic rats. Insulin treatment partly or completely reversed the changes in diabetic rats. All results yielded the conclusion that impaired hepatic CYP2C11 and intestinal BCRP expression and activity induced by diabetes contributed to the increased exposure of orally administered GLB.

Pharmacokinetics of sildenafil and its metabolite, N-desmethylsildenafil, in rats with liver cirrhosis and diabetes mellitus, alone and in combination

Pharmacokinetics of sildenafil and its metabolite, N-desmethylsildenafil, in humans and rats with liver cirrhosis (LC) and diabetes mellitus (DM), alone and in combination (LCD) did not seem to be reported. Sildenafil was administered intravenously (10 mg/kg) and orally (20 mg/kg) to control, LC, DM, and LCD rats. Expression of intestinal CYP isozymes in those rats was also measured. In LC, DM, and LCD rats, the areas under the curve (AUCs) of intravenous sildenafil were significantly greater (by 195%, 54.2%, and 127%, respectively) than controls. In LC and LCD rats, AUCs of oral sildenafil were significantly greater (3010% and 2030%, respectively) than controls. In LC, DM, and LCD rats, significantly greater AUCs of intravenous sildenafil were due to the slower hepatic extraction of sildenafil (because of decrease in the protein expression of hepatic CYP2C11 and 3A subfamily in LC and LCD rats, and CYP2C11 in DM rats). In LC and LCD rats, greater magnitude of increase in AUCs of oral sildenafil than those after the intravenous administration could be mainly due to the decrease in the intestinal extraction of sildenafil (because of decrease in the protein expression of intestinal CYP2C11 in LC and LCD rats).

Pharmacokinetics of drugs in rats with diabetes mellitus induced by alloxan or streptozocin: comparison with those in patients with type I diabetes mellitus

Objectives

In rats with diabetes mellitus induced by alloxan (DMIA) or streptozocin (DMIS), changes in the cytochrome P450 (CYP) isozymes in the liver, lung, kidney, intestine, brain, and testis have been reported based on Western blot analysis, Northern blot analysis, and various enzyme activities. Changes in phase II enzyme activities have been reported also. Hence, in this review, changes in the pharmacokinetics of drugs that were mainly conjugated and metabolized via CYPs or phase II isozymes in rats with DMIA or DMIS, as reported in various literature, have been explained. The changes in the pharmacokinetics of drugs that were mainly conjugated and mainly metabolized in the kidney, and that were excreted mainly via the kidney or bile in DMIA or DMIS rats were reviewed also. For drugs mainly metabolized via hepatic CYP isozymes, the changes in the total area under the plasma concentration–time curve from time zero to time infinity (AUC) of metabolites, AUCmetabolite/AUCparent drug ratios, or the time-averaged nonrenal and total body clearances (CLNR and CL, respectively) of parent drugs as reported in the literature have been compared.

Key findings

After intravenous administration of drugs that were mainly metabolized via hepatic CYP isozymes, their hepatic clearances were found to be dependent on the in-vitro hepatic intrinsic clearance (CLint) for the disappearance of the parent drug (or in the formation of the metabolite), the free fractions of the drugs in the plasma, or the hepatic blood flow rate depending on their hepatic extraction ratios. The changes in the pharmacokinetics of drugs that were mainly conjugated and mainly metabolized via the kidney in DMIA or DMIS rats were dependent on the drugs. However, the biliary or renal CL values of drugs that were mainly excreted via the kidney or bile in DMIA or DMIS rats were faster.

Summary

Pharmacokinetic studies of drugs in patients with type I diabetes mellitus were scarce. Moreover, similar and different results for drug pharmacokinetics were obtained between diabetic rats and patients with type I diabetes mellitus. Thus, present experimental rat data should be extrapolated carefully in humans.

Gout: an independent risk factor for all-cause and cardiovascular mortality

OBJECTIVE

The relation of gout and hyperuricaemia to cardiovascular diseases has been well documented. This study investigates the survival impact of both gout and hyperuricaemia.

METHODS

The subjects of this study comprised participants of a health screening programme conducted by the Chang Gung Memorial Hospital in Taiwan from 2000 to 2006. The status and causes of death were ascertained by the Taiwan National Death Registry 2000-07. Cox proportional hazard model was performed to examine the association.

RESULTS

Among 61 527 subjects, 1383 deaths (198 cardiovascular deaths) were identified, corresponding to a crude mortality rate of 4.86 deaths per 1000 person-years. Crude mortality rates were 4.50, 5.61 and 10.46 deaths per 1000 person-years for subjects with normouricaemia, hyperuricaemia and gout, respectively. Compared with subjects with normouricaemia, the hazard ratios (HRs) of all-cause mortality were 1.46 (95% CI 1.12, 1.91) for individuals with gout and 1.07 (95% CI 0.94, 1.22) for those with hyperuricaemia, respectively, after adjustments were made for age, sex, component number of metabolic syndrome and proteinuria. The adjusted HRs of cardiovascular mortality were 1.97 (95% CI 1.08, 3.59) for individuals with gout and 1.08 (95% CI 0.78, 1.51) for those with hyperuricaemia. Moreover, the risk of all-cause or cardiovascular mortality for gout remained unchanged when limiting the data to those with an estimated glomerular filtration of >60 ml/min/1.73 m(2).

CONCLUSION

This study demonstrates a link of gout, not hyperuricaemia, with a higher risk of death from all causes and cardiovascular diseases.