Slower clearance of intravenous metformin in rats with acute renal failure induced by uranyl nitrate: Contribution of slower renal and non-renal clearances

Slower Elimination of Tofacitinib in Acute Renal Failure Rat Models: Contribution of Hepatic Metabolism and Renal Excretion

Tofacitinib is a Jak inhibitor developed as a treatment for rheumatoid arthritis. Tofacitinib is metabolized mainly through hepatic CYP3A1/2, followed by CYP2C11. Rheumatoid arthritis tends to increase renal toxicity due to drugs used for long-term treatment. In this study, pharmacokinetic changes of tofacitinib were evaluated in rats with gentamicin (G-ARF) and cisplatin-induced acute renal failure (C-ARF). The time-averaged total body clearance (CL) of tofacitinib in G-ARF and C-ARF rats after 1-min intravenous infusion of 10 mg/kg was significantly decreased by 37.7 and 62.3%, respectively, compared to in control rats. This seems to be because the time-averaged renal clearance (CL_R) was significantly lower by 69.5 and 98.6%, respectively, due to decreased creatinine clearance (CL_CR). In addition, the time-averaged nonrenal clearance (CL_NR) was also significantly lower by 33.2 and 57.4%, respectively, due to reduction in the hepatic CYP3A1/2 and CYP2C11 subfamily in G-ARF and C-ARF rats. After oral administration of tofacitinib (20 mg/kg) to G-ARF and C-ARF rats, both CL_R and CL_NR were also significantly decreased. In conclusion, an increase in area under plasma concentration-time curves from time zero to time infinity (AUC) of tofacitinib in G-ARF and C-ARF rats was due to the significantly slower elimination of tofacitinib contributed by slower hepatic metabolism and urinary excretion of the drug.

Clearance kinetics of the VGF-derived neuropeptide TLQP-21

TLQP-21 is a multifunctional neuropeptide and a promising new medicinal target for cardiometabolic and neurological diseases. However, to date its clearance kinetics and plasma stability have not been studied. The presence of four arginine residues led us to hypothesize that its half-life is relatively short. Conversely, its biological activities led us to hypothesize that the peptide is still taken up by adipose tissues effectively. [¹²⁵I]TLQP-21 was i.v. administered in rats followed by chasing the plasma radioactivity and assessing tissue uptake. Plasma stability was measured using LC-MS. In vivo lipolysis was assessed by the palmitate rate of appearance.

RESULTS

A small single i.v. dose of [¹²⁵I]TLQP-21 had a terminal half-life of 110 min with a terminal clearance rate constant, k_t, of 0.0063/min, and an initial half-life of 0.97 min with an initial clearance rate constant, k_i, of 0.71/min. The total net uptake by adipose tissue accounts for 4.4% of the entire dose equivalent while the liver, pancreas and adrenal gland showed higher uptake. Uptake by the brain was negligible, suggesting that i.v.-injected peptide does not cross the blood-brain-barrier. TLQP-21 sustained isoproterenol-stimulated lipolysis in vivo. Finally, TLQP-21 was rapidly degraded producing several N-terminal and central sequence fragments after 10 and 60 min in plasma in vitro. This study investigated the clearance and stability of TLQP-21 peptide for the first time. While its pro-lipolytic effect supports and extends previous findings, its short half-life and sequential cleavage in the plasma suggest strategies for chemical modifications in order to enhance its stability and therapeutic efficacy.

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.

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.

Effects of acute renal failure induced by uranyl nitrate on the pharmacokinetics of liquiritigenin and its two glucuronides, M1 and M2, in rats

OBJECTIVES

Liver disease and acute renal failure (ARF) are closely associated. The pharmacokinetics of liquiritigenin (LQ), a candidate therapy for inflammatory liver disease, and its metabolites M1 and M2 were evaluated in rats with ARF induced by uranyl nitrate (U-ARF rats).

METHODS

LQ was administered intravenously (20 mg/kg) or orally (50 mg/kg) in U-ARF and control rats, and uridine diphosphate-glucuronosyltransferases (UGT) activity and uridine 5'-diphosphoglucuronic acid (UDPGA) concentrations were determined in the liver and intestine.

KEY FINDINGS

After intravenous LQ administration, U-ARF rats displayed significantly slower LQ renal clearance but no significant changes in the LQ area under the plasma concentration-time curve (AUC) compared with controls. This was because of similar hepatic UGT activity and UDPGA levels between two groups, which resulted in comparable non-renal clearance, as well as the limited contribution of LQ renal clearance to total LQ clearance. However, the AUC and AUC(M) /AUC(LQ) ratios of M1 and M2 were significantly increased in U-ARF rats because of decreased urinary excretion of M1 and M2. Similar results were observed following oral administration because of the comparable LQ intestinal metabolism in both groups and decreased urinary excretion of M1 and M2 in U-ARF rats.

CONCLUSIONS

U-ARF rats displayed decreased urinary excretion of LQ glucuronides, resulting in significantly greater AUC and metabolite ratios of M1 and M2 following LQ administration.