Total and Unbound Pharmacokinetics of Cefiderocol in Critically Ill Patients

BACKGROUND

Cefiderocol is a siderophore cephalosporin antibiotic active against Gram-negative bacteria, including extended-spectrum beta-lactamase and carbapenemase-producing strains. The pharmacokinetics of cefiderocol has been studied in healthy subjects and particularly in phase II and III studies. This retrospective study investigated intravenous cefiderocol population pharmacokinetics in adult patients treated by cefiderocol.

METHODS

We studied 55 consecutive patients hospitalized in an intensive care unit. Cefiderocol plasma samples were obtained on different occasions during treatment. Plasma concentration was assayed using mass spectrometry. Data analysis was performed using a non-linear mixed-effect approach via Monolix 2020R1.

RESULTS

A total of 205 plasma samples were obtained from 55 patients. Eighty percent of patients received cefiderocol for ventilator-associated pneumonia due to carbapenem-resistant Pseudomonas aeruginosa infection. Cefiderocol concentration time-courses were best fit to a two-compartment open model with first-order elimination. Elimination clearance was positively related to renal function (estimated by the CKD formula). Adding albumin plasma binding in the model significantly improved the model assuming a ~40% unbound drug fraction given a ~40 g/L albuminemia. The final model included CKD plus cefiderocol plasma binding effects. Fat-free mass was better than total body weight to influence, via the allometric rule, clearance and volume terms, but this effect was negligible. The final clearance based on free circulating drug (CL_U) for a typical patient, CKD = 90, was 7.38 L/h [relative standard error, RSE, 22%] with a between-subject variability of 0.47 [RSE 10%] (exponential distribution).

CONCLUSION

This study showed that albumin binding and CKD effects were significant predictors of unbound and total plasma cefiderocol concentrations. Our results indicate that individual adjustment of cefiderocol can be used to reach high minimum inhibitory concentrations based on an estimation of unbound drug concentration and optimize therapeutic efficacy.

Simple and accurate quantitative analysis of cefiderocol and ceftobiprole in human plasma using liquid chromatography-isotope dilution tandem mass spectrometry: interest for their therapeutic drug monitoring and pharmacokinetic studies

OBJECTIVES

Cefiderocol and ceftobiprole are new generation cephalosporin antibiotics that exhibit high inter-individual plasma concentration variability that potentially impact their efficacy or toxicity. The aim of this study was to develop and validate a selective, simple, and fast UPLC-MS/MS method for simultaneous quantification of cefiderocol and ceftobiprole in human plasma to enable their therapeutic drug monitoring (TDM) and support PK and PK/PD studies, in particular in critically ill patients.

METHODS

After a simple and fast single-step protein precipitation, cefiderocol and ceftobiprole were separated on a Waters Acquity UPLC BEH C18 column by linear gradient elution; with subsequent detection by Shimadzu MS 8060 triple quadrupole tandem mass spectrometer in a positive ionization mode.

RESULTS

Analysis time was 5 min per run. The analytical performance of the method in terms of specificity, sensitivity, linearity, precision, accuracy, matrix effect (ME), extraction recovery (ER), limit of quantification, dilution integrity, and stability of analytes under different conditions met all criteria for a bioanalytical method for the quantification of drugs. The calibration curves were linear over the range of 1-200 mg/L for cefiderocol and 0.5-100 mg/L for ceftobiprole with a linear regression coefficient above 0.995 for both.

CONCLUSIONS

A simple, fast, and selective liquid chroma-tography-tandem mass spectrometry method was developed and validated for the simultaneous quantification of cefiderocol and ceftobiprole. This new method was successfully applied to the measurement of plasma concentration of cefiderocol and ceftobiprole in critically ill patients and showed good performance for their therapeutic monitoring and optimizing antibiotic therapy.

Ciprofloxacin population pharmacokinetics during long-term treatment of osteoarticular infections

BACKGROUND

Ciprofloxacin is an antibiotic used in osteoarticular infections owing to its very good bone penetration. Very few pharmacokinetic data are available in this population.

OBJECTIVES

To investigate oral ciprofloxacin population pharmacokinetics in adult patients treated for osteoarticular infections and propose guidance for more effective dosing.

METHODS

A retrospective population-pharmacokinetic analysis was performed on 92 consecutive hospitalized patients in the orthopaedic department. Ciprofloxacin plasma samples were obtained on one or two occasions during treatment. Plasma concentration was measured using ultra-performance liquid chromatography system coupled with tandem mass spectrometry. Data analysis was performed using a non-linear mixed-effect approach via Monolix 2019R2.

RESULTS

A total of 397 plasma samples were obtained with 11.5% and 41.6% of patients being below the therapeutic target for Gram-negative and staphylococcal infections, respectively. Ciprofloxacin pharmacokinetics were best described by a two-compartment model with a first-order absorption. Ciprofloxacin apparent plasma clearances and volumes of distribution were dependent on patients' fat-free mass according to the allometric rule. Elimination clearance was also positively related to renal function through the modification of diet in renal disease equation (MDRD) and rifampicin co-administration. When patients are co-treated with rifampicin, ciprofloxacin dosage should be increased by 50% to 60%.

CONCLUSIONS

This study showed that free-fat mass was a better size predictor than total body weight for ciprofloxacin clearance and volumes terms. Moreover, both MDRD and rifampicin status were significant predictors of individual ciprofloxacin clearance. Our study suggests that individual adjustment of ciprofloxacin dose in osteoarticular infections with less-susceptible bacteria might be indicated to reach required efficacy targets.

Development and clinical validation of a simple and fast UPLC-ESI-MS/MS method for simultaneous quantification of nine kinase inhibitors and two antiandrogen drugs in human plasma: Interest for their therapeutic drug monitoring

Kinase inhibitors (KIs) and antiandrogen drugs (AAs) are oral anticancer drugs with narrow therapeutic index that exhibit high inter- and intra-individual variability. We describe here a UPLC-MS/MS method for the simultaneous quantification of nine KIs: cobimetinib, dasatinib, ibrutinib, imatinib, nilotinib, palbociclib, ruxolitinib, sorafenib and vemurafenib; two active metabolites of them: N-desmethyl imatinib, N-oxide sorafenib; and two AAs: abiraterone and enzalutamide; with short pre-treatment and run time in order to be easily used in clinical practice for their therapeutic drug monitoring (TDM) and facilitating pharmacokinetics and pharmacokinetics/pharmacodynamics studies. Plasma samples were prepared by a single-step protein precipitation. Analytes were separated on a Waters Acquity UPLC® T3 HSS C18 column by non-linear gradient elution; with subsequent detection by Xevo® TQD triple quadrupole tandem mass spectrometer in a positive ionization mode. Analysis time was 2.8 min per run, and all analytes eluted within 1.46-1.97 minutes. The analytical performance of the method in terms of specificity, sensitivity, linearity, precision, accuracy, matrix effect, extraction recovery, limit of quantification, dilution integrity and stability of analytes under different conditions met all criteria for a bioanalytical method for the quantification of drugs. The calibration curves were linear over the range of 1-500 ng/mL for abiraterone, dasatinib and ibrutinib; 5-500 ng/mL for cobimetinib and palbociclib; 10-5,000 ng/mL for imatinib, N-desmethyl imatinib, nilotinib, sorafenib, N-oxide sorafenib and ruxolitinib; 100-50,000 ng/mL for enzalutamide and 100-100,000 ng/mL for vemurafenib with coefficient of correlation above 0.995 for all analytes. This novel method was successfully applied to TDM in clinical practice.

Pharmacokinetics and pharmacodynamics of hydroxychloroquine in hospitalized patients with COVID-19

BACKGROUND

Hydroxychloroquine (HCQ) dosage required to reach circulating levels that inhibit SARS-Cov-2 are extrapolated from pharmacokinetic data in non-COVID-19 patients.

METHODS

We performed a population-pharmacokinetic analysis from 104 consecutive COVID-19 hospitalized patients (31 in intensive care units, 73 in medical wards, n=149 samples). Plasma HCQ concentration were measured using high performance liquid chromatography with fluorometric detection. Modelling used Monolix-2019R2.

RESULTS

HCQ doses ranged from 200 to 800mg/day administered for 1 to 11days and median HCQ plasma concentration was 151ng/mL. Among the tested covariates, only bodyweight influenced elimination oral clearance (CL) and apparent volume of distribution (Vd). CL/F (F for unknown bioavailability) and Vd/F (relative standard-error, %) estimates were 45.9L/h (21.2) and 6690L (16.1). The derived elimination half-life (t1/2) was 102h. These parameters in COVID-19 differed from those reported in patients with lupus, where CL/F, Vd/F and t1/2 are reported to be 68L/h, 2440 L and 19.5h, respectively. Within 72h of HCQ initiation, only 16/104 (15.4%) COVID-19 patients had HCQ plasma levels above the in vitro half maximal effective concentration of HCQ against SARS-CoV-2 (240ng/mL). HCQ did not influence inflammation status (assessed by C-reactive protein) or SARS-CoV-2 viral clearance (assessed by real-time reverse transcription-PCR nasopharyngeal swabs).

CONCLUSION

The interindividual variability of HCQ pharmacokinetic parameters in severe COVID-19 patients was important and differed from that previously reported in non-COVID-19 patients. Loading doses of 1600mg HCQ followed by 600mg daily doses are needed to reach concentrations relevant to SARS-CoV-2 inhibition within 72hours in≥60% (95% confidence interval: 49.5-69.0%) of COVID-19 patients.

[Diagnostic effectiveness of CT and MR in local staging of renal tumors]

The aim of this paper is to study the pre-operative staging of renal tumours, comparing CT and MR, and the imaging criteria used, examining the diagnostic efficacy for each of them. Thirty-four tumours were obtained from 29 patients. All cases were studied with CT and MR. To measure diagnostic efficacy, both for each technique and the criteria used in 2 different readings, a diagnostic performance curve (DPC) is calculated. Neither CT nor MR show infiltration of renal capsule. With regard to perinephritic fat, fascia and adjacent organ invasion, both techniques lead to overstaging, mainly CT. When applying more conservative reading criteria, the results are much improved, specially in relation to CT, although results with MR continue to be more favourable. MR is better to study vascular invasion, providing no false results. Of 22 tumours undergoing surgery, first option was the correct staging in 14 tumour with CT and in 16 with MR. When selecting the best imaging technique to stage renal tumours, MR allows a better and simpler radiologic reading. Nevertheless, considering the high correlation between CT and MR, CT can be used more reliably in institutions where no easy access to a MR unit is available. Both CT and MR overstage renal tumours.

Carcinoma of prostatic ducts

Carcinoma of prostatic ducts is a rare clinical feature. We have reviewed 398 histories of patients with histologic diagnosis of prostatic carcinoma and found 10 patients with the ductal variety (2.51%). Four had pure ductal transitional cell carcinoma, 5 had mixed acinar adenocarcinoma plus ductal transitional cell carcinoma, and the last one had mixed acinar and ductal adenocarcinoma. Age, symptoms, physical findings, and imaging diagnoses were similar to those of acinar carcinoma. Rectal examination disclosed hard prostate in 9 patients. The metastatic way depended on the histologic elements present in each patient. Cystoscopy showed a malignant-resembling image in 4 cases. The mean survival (23 months) was lower than that of patients with acinar carcinoma. Early diagnosis and radical surgery still are the only way to increase the expectation of life of patients affected by this pathology.

[Penoscrotal gangrene: our series of cases]

Ten cases of penoscrotal gangrene seen in our department over the last 8 years are presented. In 80% of patients causative factors of the gangrenous process were demonstrated and were equally distributed between urology and colorectal pathologies. The most commonly associated pathology was diabetes mellitus affecting up to 50% of our patients. Two or more germs were isolated from the necrotic-purulent material for cultures, mainly E. coli (90%) and Proteus mirabilis (50%) as aerobic organisms, and Bacteroides fragilis (40%) in the anaerobic group. Despite emergency surgical therapy and high doses of broad spectrum antibiotics, mortality in our series was about 20%.

[Surgical treatment of urinary stress incontinence in women]

Long-term results obtained in 54 surgical procedures to correct effort urinary incontinence performed in 49 patients with this pathology are reviewed. One group was treated with suprapubic urethrovesical suspension with the Marshall-Marchetti-Krantz technique; the other group with endoscopic suspension of the neck of the bladder, with the Stamey technique and the third group with sling techniques. The authors conclude that any of the surgical techniques achieving a correct reposition of urethrovesical anatomy, rising the posterior urethra to its primitive anatomical bed, obtain a similar success rate.

Follow-up of superficial bladder cancer: how to spare cystoscopies?

To study the efficacy, specificity and sensitivity of ultrasonography, cytology and phospholipid/fatty acid quotient (PL/FA) in the detection of recurrences in patients with superficial bladder cancer we performed these three examinations simultaneously with cystoscopy. In over 405 cystoscopies, 348 were negative and 57 were positive for tumor. Sensitivity, the most important parameter, was 73% for the three examinations together. Each method separately had the following sensitivity: ultrasound 26%; cytology 14%, and PL/FA 47%. Considering that there were only 15 false-negatives, with this follow-up scheme we save the patient from a lot of cystoscopies, avoiding their inherent morbidity.

ABO blood groups and bladder carcinoma

Following some reports concerning the possible influence of ABO blood groups on constitutional types and different features of human pathology, we have investigated if there are relationships between ABO blood groups and bladder tumors. Our findings show that tumoral behavior in patients with bladder carcinoma and blood group O has a tendency to an increased aggressivity with higher tumoral grade and more relapses than what is seen in tumors of patients with A blood group. Although this difference is not statistically significant, we believe that blood group ABO should be considered as a constitutional prognostic factor in bladder carcinoma and further investigations in this field are needed.

Selective chemoprophylaxis guided by multifactorial analysis in superficial bladder cancer

One hundred and five patients with superficial bladder cancer (60 primary and 45 recurrent tumors) entered a prospective chemoprophylaxis trial after transurethral resection of the tumor. The drug for chemoprophylaxis was chosen by a computer which received the tumor data and analyzed them through a previous program of recurrence risk factors (multivariant analysis). In comparison with the aleatory selection of the drug, this statistical computerized choice has diminished the recurrence index (from 8 to 3) and increased the interval free of disease (from 70 to 83.5 months) in this group of patients.

[Disseminated renal adenocarcinoma. Developmental study]

A study was undertaken on 57 patients diagnosed as having disseminated renal adenocarcinoma. The interval between the onset of symptomatology and diagnosis ranged from 1 to 48 months. The tumor frequently metastasized to lungs and bone. To evaluate survival, this patient population was divided into two groups: those who underwent nephrectomy, 17 patients (9 patients also underwent lymphadenectomy), and those who were put on drug therapy alone. No significant difference was observed with respect to survival for both patient groups.

[Percutaneous nephrostomy as a technic for emergency drainage: review of cases]

Percutaneous nephrostomy (PCN) is currently one of the procedures of choice for emergency drainage of the upper urinary tract. Moreover, it permits morphologic and functional diagnostic possibilities as well as a wide variety of new and frequently definitive therapeutic procedures. We report on 58 PCN procedures performed in 55 patients from May 1983 to February 1989. PCN was indicated for complicated or uncomplicated uni- or bilateral supravesical obstruction, with infection and/or azotemia. All patients submitted to PCN for complicated obstruction with infection and/or azotemia showed a marked clinical and analytical improvement. Apart from resolving this emergency, it reduced the morbidity and mortality rate of subsequent surgical treatment of the underlying cause of obstruction because patient status was markedly improved. The major complications, retroperitoneal hematoma and sepsis, were rare. We frequently observed that the catheter had come out or become obstructed in our series. PCN affords the following advantages: it can be performed with local anesthesia; it is a simple technique; there are no absolute contraindications; its morbidity and mortality rates are low; and, it can be easily converted into a permanent procedure. In our view, all the foregoing advantages, as well as its therapeutic and morphologic and functional diagnostic possibilities, make PCN one of the procedures of choice in emergency treatment of upper urinary tract obstruction.

[Calcification and contamination as complications in the use of double-J catheters: incidence and correlation]

We present a series of cases of complex renal lithiasis, in which we carried out temporary internal urinary bypassing, prior to extracorporeal lithotripsy, by means of the retrograde insertion of a double-J urethral catheter, studying the time of stay, the presence or not of contamination in the catheter and its relationship with the calcifications found in them. We also carried out a metabolic-functional study of each patient, determining the urinary pH and the serum and urinary calcium, phosphorous and uric acid concentrations, and observing their possible influence on the above-mentioned complications. Of the 25 catheters studied, we observed calcification in 11 cases (44%). In these we observed urealytic germs (Proteus and Pseudomonas), without finding modifications of urinary pH. We observed no relationship between the calcium deposits and serum and urinary calcium, phosphorous and uric acid concentration.

[Aztreonam versus tobramycin in acute pyelonephritis. A comparative study]

We performed a comparative study between the monobactam antibiotic aztreonam and the aminoglycoside tobramycin in patients diagnosed as having acute pyelonephritis. The respective doses were 1 gr. IM daily for 7 days, and 100 mgr. IM q 12 h for the same period of time. Clinically, 100% of uncomplicated acute pyelonephritis and 87.5% of complicated infections cured with aztreonam. Tobramycin achieved an 80% cure rate for both types of infections. Microbiologically aztreonam was effective in all uncomplicated acute pyelonephritis, and in 69.56% of the complicated cases (overall microbiological cure rate = 78.7%). The therapeutic failures were ascribable to infections from S. faecalis, an organism naturally resistant to aztreonam. Thus, the microbiological cure rate was 84.2% in complicated pyelonephritis from organisms sensitive to this antimicrobial. The microbiological cure rate for tobramycin was 70% in acute uncomplicated, and 80% in complicated infections. We observed a good clinical and biological tolerance to both antimicrobials. No side effects were observed. Serum and blood biochemical analyses, and coagulation tests revealed no changes.

[Modification of the echographic pattern of carcinoma of the prostate treated with Lh-rh agonists]

We present the results of a study undertaken to assess the echo patterns and prostate size in 13 patients with prostatic carcinoma treated with Lh-rh agonists. The study revealed a gradual reduction of the anteroposterior and transverse diameters. After 12 months, these were 28% and 22% of their respective initial values. Furthermore, the prostatic echo patterns changed significantly in 66% of the patients, and infiltration of the seminal vesicle improved or became stable in 50%. These findings suggest that transrectal ultrasonography may be useful in the follow up of prostatic carcinoma patients receiving hormone therapy.

[Kidney pelvis calcification around a double-J ureteral catheter which was impossible to extract. Apropos of a case]

We present a case of pyelorenal calcification on double-J ureteral catheter, which made endoscopic extraction impossible. We review the literature and describe the incidence, methods of diagnosis and treatment of this complication, as well as the means used to avoid it.

Immunoprophylaxis with Calmette-Guérin bacillus in recurrent superficial bladder tumors

26 patients with superficial bladder cancer underwent complete removal of tumors by transurethral resection and entered a prospective trial of immunoprophylaxis with Calmette-Guérin bacillus (BCG). The entire group had recurrent tumors that failed to respond to previous prophylaxis with thiotepa (13 patients) or other drugs (13 patients). Intravesical administration of BCG reduced the recurrence index and increased the disease-free interval. Side effects were mild and well tolerated. BCG seems to be effective in the prophylaxis of superficial bladder tumor recurrence after the failure of other drugs.

[Directed chemotherapy in superficial carcinoma of the bladder conditioned by the knowledge of recurrence factors]

A retrospective study of 56 patients (23 primary and 36 relapsing) with superficial vesical carcinoma and treated with transurethral resection and directed chemoprophylaxis was done. Directed chemoprophylaxis is define as a specific type of adjuvant therapy where the drug is determined by a previous study with multivariant analysis of the relapse risk factors of a group of 385 cases, where the chemotherapeutic agent was also a variable. The drug is specified by the data introduced in a microprocessor program. Such chemoprophylactic approach has achieved a marked reduction in the relapse rate and increased the disease-free interval from 8 to 3 and from 70 to 83.5 respectively, with regard to the free drug choice approach.

Retroperitoneal malignant fibrous histiocytoma

Five cases of malignant fibrous histiocytoma located in the retroperitoneum are reported. Paraneoplastic syndrome, abdominal mass, tendency to local recurrence, laborious therapy and poor prognosis are the clinical characteristics of this tumor. Accuracy of actual diagnosis is evaluated and pathological features are analyzed.

Crossed chemoprophylaxis assay between adriamycin and cis-platinum in recurrent superficial bladder tumor

Of 146 patients with superficial bladder carcinoma, 66 (35 primary and 31 recurrent from failure of thiotepa chemoprophylaxis) relapsed following transurethral resection (TUR) and chemotherapy with adriamycin or cis-platinum. A new TUR was carried out. In case of progression in the number of tumors, size, stage or grade, treatment was begun with the other drug. If the tumor had the same characteristics, treatment was continued with the same drug. In both the primary and recurrent tumors with or without progression, cis-platinum controlled the tumor better than adriamycin, rescuing it from the latter and obtaining a recurrence index and disease-free interval as with cis-platinum alone. These results are more conclusive in primary tumors.

Thiotepa versus adriamycin versus cis-platinum in the intravesical prophylaxis of superficial bladder tumors

A study was performed on 184 patients with superficial bladder cancer (pTa, pT1), 92 with primary and 92 recurrent tumors. After TUR of all visible lesions, endovesical chemotherapy with thiotepa, adriamycin or cis-platinum was started on the 15th and 30th days following surgery. There were no statistically significant differences between any of the three chemotherapies at the doses and intervals mentioned. Only cis-platinum has proven to be more effective in primary high grade tumor.

Urinary lipids in vesical carcinoma: a new biological marker. Preliminary study

We have determined urinary lipids by thin-layer chromatography in 40 patients with bladder tumors, and have evaluated their modification following tumor removal and their predictive value in terms of the presence or absence of recurrences. The results obtained were compared with those of a control group without tumoral pathology (14 patients) and 11 cases with bacterial infection of the urinary tract. There is a marked difference between the lipidogram of the tumoral group of patients and the controls (p less than 0.005), especially in the phospholipid to fatty acid (PL/FA) relationship, with a specificity of 100% and a sensitivity of 80%. With regard to recurrences, in non-recurrent cases the PL/FA value remained high in relation to the initial value (p less than 0.005), whereas in the recurrent cases the value rose to 'tumoral limits'. Macrohematuria and urinary infection modify the lipidogram, resulting in values similar to the tumoral cases. Their absence is therefore essential in order to evaluate the results. The urinary lipidogram appears to be a possible biological marker for bladder tumors.