Biliary excretion and choleretic effect of cefmetazole in rats

Pharmacokinetics/pharmacodynamics analysis and establishment of optimal dosing regimens using unbound cefmetazole concentration for patients infected with Extended-Spectrum β-lactamase producing Enterobacterales (ESBL-E)

STUDY OBJECTIVE

Establish methods for measuring cefmetazole (CMZ) concentrations conduct a pharmacokinetic/pharmacodynamic (PK/PD) analysis using unbound CMZ concentrations for extended-spectrum β-lactamase producing enterobacterales (ESBL-E) and investigate optimal dosing regimens for not undergoing hemodialysis (non-HD) and undergoing hemodialysis (HD) patients.

DESIGN

Prospective observational study.

PATIENTS

Included patients treated with CMZ who provided written informed consent and were admitted to the Tokyo Bay Urayasu Ichikawa Medical Center between August 2021 and July 2022.

MEASUREMENTS

Total and Unbound CMZ concentration was measured by high-performance liquid chromatography (HPLC) with solid-phase extraction and ultrafiltration.

SETTING

Determining the CMZ dosing regimen involved modified creatinine clearance (CLCR ) with measured body weight (BW) using the Cockcroft-Gault equation. For non-HD patients, blood samples were collected during at least three points. For patients undergoing HD, 1 g was administered via intravenous infusion, or rapid intravenous injection after HD, or 30 min before the end of HD. Blood samples were collected before HD (pre-HD), and 1 and 3 h after starting HD and post-HD. All blood samples were collected at steady-state. Patient information was collected from electronic medical records. An unbound PK model was constructed for the non-HD patients. A nomogram was constructed using Monte Carlo simulations with a 90% probability of target attainment at 70% free time above the minimum inhibitory concentration (MIC). For the HD patients, a nomogram was used to determine the optimal dosing regimen for each HD schedule.

MAIN RESULTS

CMZ measurement methods were established. A model analysis of unbound PK in 37 non-HD patients incorporated creatinine clearance (CLCR ) using the Cockcroft-Gault equation, albumin (ALB) for clearance and body weight (BW) for the volume of distribution. In Monte Carlo simulations, nomograms corresponding to the MIC (known and unknown) were generated for each covariate. Using the nomogram, non-HD patients with an ESBL-E MIC of 8 mg/L, a BW of 60 kg, an ALB of 25 g/L, and a CLCR of 60 mL/min required administration of 2 g every 6 h (1- and 3-h infusions). Unbound PK model parameters were calculated for 7 HD patients, and the optimal dosing regimens following PK/PD were determined for each HD schedule. In HD patients, the regimen after and during HD was established using a treatment that was effective up to an ESBL-E MIC of 4 mg/L.

CONCLUSIONS

The nomogram for CMZ regimens established by PK/PD analysis of measured CMZ concentrations enables optimal CMZ dosing for ESBL-E-infected patients.

Selection of prophylactic antibiotics according to the microorganisms isolated from surgical site infections (SSIs) in a previous series of surgeries reduces SSI incidence after pancreaticoduodenectomy

BACKGROUND

The incidence of surgical site infections (SSIs) is high after pancreaticoduodenectomy (PD).

METHODS

We divided 116 consecutive patients who underwent PD into an early group (n = 58) and a later group (n = 58) according to time of surgery. In both groups, endoscopic retrograde biliary drainage was mainly employed for the patients with obstructive jaundice. In the later group, prophylactic antibiotics were selected according to the susceptibility of microorganisms isolated from SSIs in the early group. The incidence of SSIs was compared between the groups.

RESULTS

The background characteristics (including methods of preoperative biliary drainage and microorganisms in the bile obtained before or during operation) of the patients were not significantly different between the groups, except for the serum albumin level, which was lower in the later group than in the early group (P = 0.0026). The incidence of SSIs was significantly lower in the later group (24.1 %) than in the early group (46.6 %) (P = 0.0116). Belonging to the later group was one independent negative risk factor for SSI.

CONCLUSIONS

Selection of prophylactic antibiotics on the basis of microorganisms isolated from SSIs in the early group contributed to the reduced incidence of SSIs in the later group after PD.

Effect of antibiotic treatment on fat absorption in mice with cystic fibrosis

INTRODUCTION

Improving fat absorption remains a challenge in cystic fibrosis (CF). Antibiotics (AB) treatment has been shown to improve body weight in CF mice. The mechanism may include improvement in fat absorption. We aimed to determine the effect of AB on fat absorption in two CF mouse models.

RESULTS

AB did not improve total fat absorption. Interestingly, AB accelerated the absorption of isotope-labeled fats, in both Δ/Δ and WT mice. The changes observed were not related to the solubilization capacity of bile or to changes in the bacteria in the small intestine. AB reduced the fecal excretion of cholate by ~50% (P < 0.05) in both CF mouse models, indicating improved intestinal bile salt absorption.

DISCUSSION

In conclusion, AB treatment does not improve total fat absorption in CF mice but does decrease fecal loss of bile salts and accelerate long-chain fatty acid (LCFA) absorption.

METHODS

For 3 weeks, we administered oral AB (ciprofloxacin/metronidazole) or control treatment to homozygous ΔF508 (Δ/Δ), cystic fibrosis transmembrane conductance regulator (CFTR) knockout (-/-), and wild-type (WT) mice and quantified fat absorption using a 72-h fat balance test. In Δ/Δ mice, we assessed fat absorption kinetics by administering tri-1-(13)C-palmitin and 1-(13)C-stearate intragastrically and determining the appearance of stable isotope-labeled fats in plasma. We quantified biliary and fecal bile salts (gas chromatography) and small intestinal bacteria (quantitative-PCR).

4-Hydroxyacetophenone-Induced Choleresis in Rats is Mediated by the Mrp2-Dependent Biliary Secretion of Its Glucuronide Conjugate

PURPOSE

The present study examined the underlying mechanism by which 4-hydroxyacetophenone (4-HA), a bioactive compound found in several medicinal herbs, exerts its potent stimulatory effects on hepatic bile secretion.

METHODS

Bile flow, and biliary excretion of 4-HA, its metabolites, and inorganic electrolytes was examined in both normal Wistar rats and in TR(-) Wistar rats that have a congenital defect in the multidrug resistance-associated protein-2, Mrp2/Abcc2. The effects of 4-HA were also examined in animals treated with buthionine sulfoximine to decrease hepatic glutathione (GSH) levels.

RESULTS

In normal rats, 4-HA dramatically increased bile flow rate, whereas it failed to exert a choleretic effect in TR(-) rats. This choleresis was not explained by increased biliary output of Na(+), K(+), Cl(-) or HCO(3) (-), or by increased biliary GSH excretion. Depletion of hepatic GSH with buthionine sulfoximine had no effect on the 4-HA-induced choleresis. HPLC analysis revealed that a single major compound was present in bile, namely.4-hydroxyacetophenone-4-O-beta-glucuronide, and that the parent compound was not detected in bile. Biliary excretion of the glucuronide was directly correlated with the increases in bile flow. In contrast to normal rats, this 4-HA metabolite was not present in bile of TR(-) rats.

CONCLUSIONS

These results demonstrate that the major biliary metabolite of 4-HA in rats is the 4-O-beta-glucuronide, a compound that is secreted into bile at high concentrations, and may thus account in large part for the choleretic effects of 4-HA. Transport of this metabolite across the canalicular membrane into bile requires expression of the Mrp2 transport protein.

Mrp2 is involved in benzylpenicillin-induced choleresis

Benzylpenicillin (PCG; 180 micromol/kg), a classic beta-lactam antibiotic, was intravenously given to Sprague-Dawley (SD) rats and multidrug resistance-associated protein 2 (Mrp2)-deficient Eisai hyperbilirubinemic rats (EHBR). A percentage of the [(3)H]PCG was excreted into the bile of the rats within 60 min (SD rats: 31.7% and EHBR: 4.3%). Remarkably, a transient increase in the bile flow ( approximately 2-fold) and a slight increase in the total biliary bilirubin excretion were observed in SD rats but not in the EHBR after PCG administration. This suggests that the biliary excretion of PCG and its choleretic effect are Mrp2-dependent. Positive correlations were observed between the biliary excretion rate of PCG and bile flow (r(2) = 0.768) and more remarkably between the biliary excretion rate of GSH and bile flow (r(2) = 0.968). No ATP-dependent uptake of [(3)H]PCG was observed in Mrp2-expressing Sf9 membrane vesicles, whereas other forms of Mrp2-substrate transport were stimulated in the presence of PCG. GSH efflux mediated by human MRP2 expressed in Madin-Darby canine kidney II cells was enhanced in the presence of PCG in a concentration-dependent manner. In conclusion, the choleretic effect of PCG is caused by the stimulation of biliary GSH efflux as well as the concentrative biliary excretion of PCG itself, both of which were Mrp2 dependent.

Choleresis and inhibition of biliary lipid secretion induced by piperacillin in the rat

1. The effects of the administration piperacillin on bile flow and biliary lipid secretion were studied in male Wistar rats. 2. Intravenous injection of piperacillin at doses ranging from 0.3 to 3.0 mmol/kg bodyweight led to an increase in its biliary concentration and excretion rate. Maximal biliary excretion was reached at a dose of 2.0 mmol/kg piperacillin. 3. Excretion of the antibiotic into bile was associated with a marked choleresis. A linear relationship was observed between bile flow and piperacillin excretion, 5.7 micro L bile being produced per micro mol piperacillin excreted into the bile. 4. Continuous i.v. infusion of piperacillin at 2.0 mmol/100 g per min did not result in significant changes in bile acid or cholesterol secretion, but biliary phospholipid secretion was markedly reduced. The inhibitory effect on phospholipid secretion was also present when biliary lipid output had been previously increased by an infusion of taurocholate (200 nmol/100 g per min). Addition of taurocholate did not reverse the impairment of phospholipid secretion induced by piperacillin. 5. These results indicate that acute administration of piperacillin in the rat induces a marked choleresis by stimulating bile acid-independent bile flow. The significant impairment in phospholipid secretion suggests a specific effect on intracellular supply and/or translocation across the canalicular membrane.

Effects of diabetes on disposition and hepatic handling of cefmetazole in rats

1. The effects of streptozotocin-induced diabetes on disposition and hepatic handling of cefmetazole, a broad-spectrum cephalosporin, were investigated in rats. 2. Male Wistar rats were pretreated with streptozotocin (60 mg/kg, i.p.) to induce uncontrolled diabetes. Fourteen days later bile flow was significantly reduced (12%) and bile acid secretion was significantly enhanced (87%) when compared with control animals. 3. Following intravenous injection of cefmetazole at a dose of 200 mumol/kg, maximal and cumulative biliary excretion of the antibiotic were significantly impaired in streptozotocin-treated animals (27 and 22%, respectively). 4. Cefmetazole excretion into bile was accompanied by marked choleresis. The magnitude of bile flow increase was larger in control animals. 5. Total systemic clearance of the antibiotic was reduced (36%) and mean half-life for the fast and slow phases of disposition increased (136 and 48%, respectively) in diabetic rats. 6. These changes were probably due to the diabetic condition of the animals because insulin treatment resulted in almost complete correction.

Effects of a hypercholesterolaemia-inducing diet on biliary electrolytes and lipid secretion in the rat

The effects of a high cholesterol/cholate diet on the biliary secretion of bile acids, cholesterol, phospholipid and inorganic electrolytes in the rat were examined. Wistar rats were fed a hypercholesterolaemia-inducing diet (HID) for 20 days prior to the biliary experiments. Rats fed a standard laboratory diet were used as controls. The HID diet increased plasma cholesterol concentrations and the hepatic content of total, free and esterified cholesterol, without changes in ALP*, ALT and AST plasma activities. Bile flow and biliary secretion of bile acids and inorganic electrolytes were markedly increased in the hypercholesterolaemic animals. The stimulated biliary secretion was due to an increase in both the bile acid-dependent and bile acid-independent fractions of bile flow. An increase in the bile acid pool induced by the administration of exogenous cholic acid/cholesterol would account for these changes in bile flow and inorganic electrolyte secretion. Nevertheless, the increase in the bile acid-independent bile flow could be also related, at least to some extent, to a higher efficiency of bicarbonate transport into bile. The HID diet also increased both cholesterol and phospholipid biliary outputs, whereas it did not modify the relationship between lipid and bile acid secretion. The lithogenic index of bile was reduced in the rats after the HID regimen due to a relatively higher increase in the biliary outputs of phospholipids and bile acids than of cholesterol.

Alterations induced by fascioliasis and cirrhosis on the biliary excretion of cefmetazole in wistar rats

1. Alterations induced by fascioliasis and cirrhosis on the biliary excretion of cefmetazole have been studied in Wistar rats. 2. Both infestation with Fasciola hepatica and experimental cirrhosis originated a significant decrease in the biliary excretion and in bile flow increase induced by the drug. 3. Administration of the beta-lactam antibiotic induced a lower degree of uncoupling of biliary lipid secretion in the cirrhotic and fasciolotic animals, but the effect was evident in all experimental groups.

Inhibition of biliary cholesterol and phospholipid secretion by cefmetazole. The role of vesicular transport and of canalicular events

A number of organic anions selectively inhibit the biliary secretion of cholesterol and phospholipids without affecting bile acid secretion. We studied the effect of cefmetazole, a third-generation cephalosporin, on biliary lipid secretion in the rat. Injection of cefmetazole at a dose of 200 mumol/kg body wt. induced a choleretic effect and a significant decrease in the biliary output of cholesterol and phospholipid, without changes in bile acid secretion. The decrease was more marked for cholesterol than for phospholipid secretion, with a significant decrease in their molar ratio in bile. The effects were apparently unrelated to an inhibition of intracellular vesicular transport because, after injection of horseradish peroxidase, both the time course and total amount secreted of the protein did not significantly differ between control animals and those receiving cefmetazole. The secretory rate of the lysosomal marker acid phosphatase was not affected by cefmetazole administration. Biliary outputs of the plasma-membrane enzymes alkaline phosphatase and gamma-glutamyltransferase were significantly decreased by the antibiotic. These results point to an effect of cefmetazole at the level of the canalicular membrane.