Nonvolatile salt-free stabilizer for the quantification of polar imipenem and cilastatin in human plasma using hydrophilic interaction chromatography/quadrupole mass spectrometry with contamination sensitive off-axis electrospray

Simultaneous determination of six antibiotics in human serum by high-performance liquid chromatography with UV detection

Antibiotics are widely used in intensive care patients to treat severe infections. To avoid bacterial resistance or toxic side effects, the determination of serum concentration of ABs is advisable. Therefore, in this study, we developed and validated a simple and fast high-performance liquid chromatography method with UV detection for the simultaneous determination of four β-lactam ABs (meropenem, imipenem, ceftazidime, and piperacillin) and two coadministered substances (cilastatin and tazobactam) in human serum. Sample preparation required a simple protein precipitation by methanol. The separation of the ABs occurred within a timeframe of 17 min. For this purpose, we used a Kinetex F5 column with a linear gradient of acetonitrile and phosphate buffer (pH 6.9). The UV detector recorded two separate chromatograms at 220 and 295 nm simultaneously. Validation has demonstrated that the method is linear, accurate, and precise within the clinically relevant range for each substance.

Organic anion transporters also mediate the drug-drug interaction between imipenem and cilastatin

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Dehydropeptidase-1 (DPEP1) mediates the DDI between imipenem and cilastatin as a traditional theory is limited.

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Transporter-mediated DDI between imipenem and cilastatin has not been clarified.

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Imipenem and cilastatin are the substrates of hOAT1/3.

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This study first demonstrates that OAT1 and OAT3 also mediate the DDI between imipenem and cilastatin.

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It also supplies a new ideal to make a compound preparation through the DDI mediated by transporters.

This study aimed to clarify that organic anion transporters (OATs) mediate the drug–drug interaction (DDI) between imipenem and cilastatin. After co-administration with imipenem, the plasma concentrations and the plasma concentration-time curve (AUC) of cilastatin were significantly increased, while renal clearance and cumulative urinary excretion of cilastatin were decreased. At the same time, imipenem significantly inhibited the uptake of cilastatin in rat kidney slices and in human OAT1 (hOAT1)-HEK293 and human OAT3 (hOAT3)-HEK293 cells. Probenecid, p-aminohippurate, and benzylpenicillin inhibited the uptake of imipenem and cilastatin in rat kidney slices and in hOAT1- and hOAT3-HEK 293 cells, respectively. The uptakes of imipenem and cilastatin in hOAT1- and hOAT3-HEK 293 cells were significantly higher than that in mock-HEK-293 cells. Moreover, the K_m values of cilastatin were increased in the presence of imipenem with unchanged V_max, indicating that imipenem inhibited the uptake of cilastatin in a competitive manner. When imipenem and cilastatin were co-administered, the level of imipenem was higher compared with imipenem alone both in vivo and in vitro. But, cilastatin significantly inhibited the uptake of imipenem when dehydropeptidase-1 (DPEP1) was silenced by RNAi technology in hOAT1- and hOAT3-HEK 293 cells. In conclusion, imipenem and cilastatin are the substrates of OAT1 and OAT3. OAT1 and OAT3 mediate the DDI between imipenem and cilastatin. Meanwhile, cilastatin also reduces the hydrolysis of imipenem by inhibiting the uptake of imipenem mediated by OAT1 and OAT3 in the kidney as a complement.

Pharmacokinetics of Imipenem/Cilastatin Burn Intensive Care Unit Patients Undergoing High-Dose Continuous Venovenous Hemofiltration

STUDY OBJECTIVE

High-dose continuous venovenous hemofiltration (CVVH) is a continuous renal replacement therapy (CRRT) used frequently in patients with burns. However, antibiotic dosing is based on inference from studies assessing substantially different methods of CRRT. To address this knowledge gap for imipenem/cilastatin (I/C), we evaluated the systemic and extracorporeal clearances (CLs) of I/C in patients with burns undergoing high-dose CVVH.

DESIGN

Prospective clinical pharmacokinetic study.

PATIENTS

Ten adult patients with burns receiving I/C for a documented infection and requiring high-dose CVVH were studied.

METHODS

Blood and effluent samples for analysis of I/C concentrations were collected for up to 6 hours after the I/C infusion for calculation of I/C total CL (CL_Total ), CL by CVVH (CL_HF ), half-life during CVVH, volume of distribution at steady state (Vd_ss ), and the percentage of drug eliminated by CVVH.

RESULTS

In this patient sample, the mean age was 50 ± 17 years, total body surface area burns was 23 ± 27%, and 80% were male. Nine patients were treated with high-dose CVVH for acute kidney injury and one patient for sepsis. The mean delivered CVVH dose was 52 ± 14 ml/kg/hour (range 32-74 ml/kg/hr). The imipenem CL_HF was 3.27 ± 0.48 L/hour, which accounted for 23 ± 4% of the CL_Total (14.74 ± 4.75 L/hr). Cilastatin CL_HF was 1.98 ± 0.56 L/hour, which accounted for 45 ± 19% of the CL_Total (5.16 + 2.44 L/hr). The imipenem and cilastatin half-lives were 1.77 ± 0.38 hours and 4.21 ± 2.31 hours, respectively. Imipenem and cilastatin Vd_ss were 35.1 ± 10.3 and 32.8 ± 13.8 L, respectively.

CONCLUSION

Efficient removal of I/C by high-dose CVVH, a high overall clearance, and a high volume of distribution in burn intensive care unit patients undergoing this CRRT method warrant aggressive dosing to treat serious infections effectively depending on the infection site and/or pathogen.

Recent advances in hydrophilic interaction chromatography for quantitative analysis of endogenous and pharmaceutical compounds in plasma samples

There is an increasing need for new analytical methods that can handle a large number of analytes in complex matrices. Hydrophilic interaction chromatography (HILIC) has recently been demonstrated as an important supplement to reversed-phase liquid chromatography for polar analytes, particularly endogenous compounds. With the increasing popularity of HILIC, progressively more polar phases with diverse functional groups have been developed. In addition, the coupling of HILIC to mass spectrometry offers the advantages of improved sensitivity by employing an organic-rich mobile phase. This article reviews recent applications of HILIC for the analysis of endogenous and pharmaceutical compounds in plasma samples. Furthermore, based on recent studies, we provide a discussion of column selection, sample pretreatment for HILIC analysis, and detection sensitivity.