Drug concentrations in the serum and cerebrospinal fluid of patients treated with norvancomycin after craniotomy

A High-Performance Liquid Chromatography—Mass Spectrometry Method for Simultaneous Determination of Vancomycin, Meropenem, and Valproate in Patients with Post-Craniotomy Infection

Vancomycin (VAN), meropenem (MER), and valproate (VPA) are commonly used to treat intracranial infection post-craniotomy and prevent associated epilepsy. To monitor their levels, we developed a novel bioassay based on liquid chromatography–tandem mass spectrometry (LC–MS/MS) for simultaneous determination of these three drugs in human serum and cerebrospinal fluid (CSF). Sample preparation by protein precipitation using acetonitrile was followed by HPLC on a Zorbax 300SB-C8 column (150 mm × 4.6 mm, 5 μm) maintained at 40 °C. The lower limit of quantification (LLOQ) was 5 ng/mL for MER, 0.1 μg/mL for VAN, and 1 μg/mL for VPA in serum and 50 ng/mL for MER, 1 μg/mL for VAN, and 2 μg/mL for VPA in CSF. This method was validated with satisfactory linearity, sensitivity, precision, accuracy, recovery, matrix effects, and stability for all analytes. The assay was then successfully applied to evaluate VPA, MER, and VAN levels in serum and CSF from patients with intracranial infection administrated by intrathecal injection. Compared with intravenous injections, an intrathecal injection can provide sufficient therapeutic effects even if the CSF levels did not reach the effective concentration reported. Our method provided a detection tool to study the effective concentrations of these three drugs in CSF from patients administered via intrathecal injection.

Norvancomycin for the Treatment of Central Nervous System MRSA Infections: a Randomized Controlled Trial: Norvancomycin for the Treatment of Central nervous system MRSA infections

Combined intravenous and intrathecal administration of norvancomycin (NVCM) is routinely employed in treating methicillin-resistant Staphylococcus aureus (MRSA) ventriculitis in patients following craniotomy. However, the optimal dosing regimen, the pharmacokinetics (PK) of NVCM in cerebrospinal fluid (CSF), and the clinical outcome are yet to be elucidated. Herein, a single-center randomized controlled trial was conducted in the Neurosurgery Department of the Second Hospital of Hebei Medical University (Shijiazhuang, China). Patients with MRSA ventriculitis after craniotomy were randomly assigned to two groups. The control group received 800 mg NVCM intravenously every 12 h, and the experimental group received 800 mg NVCM intravenously every 12 h and 16 mg NVCM intrathecal administration every 24 h. The primary outcome was the length of therapy, while the secondary outcomes included the area under the concentration-time curve in 0-24 h/minimum inhibitory concentration ratio (AUC_0-24h/MIC) of NVCM in CSF. A total of 29 patients (14 in the experimental group and 15 in the control group) were included in this study. Of these, 24 constituted the final analysis population, with 12 in each group. The average length of therapy in the experimental group was markedly shorter than that of the control group (11.2 ± 2.6 days vs. 16.6 ± 5.2 days, P = 0.005), while the AUC_0-24h/MIC in the experimental group was significantly higher than that in the control group (2306.57 ± 928.58 vs. 46.83 ± 27.48, P <0.001) with no increase in adverse reactions. Combined intravenous and intrathecal administration can shorten the treatment time of intracranial infection without higher adverse reaction risks in our research. Further studies with larger sample size are warranted to verify its safety and efficacy.

Analysis of risk factors and preventive strategies for intracranial infection after neuroendoscopic transnasal pituitary adenoma resection

OBJECTIVE

To analyse the risk factors for intracranial infection after neuroendoscopic transnasal pituitary adenoma resection (NTPAR) to provide a reference for the prevention and treatment of postoperative intracranial infection.

METHODS

The clinical data of 387 patients who underwent NTPAR in the Department of Neurosurgery of the First People's Hospital of Yichang from March 2013 to March 2021 were retrospectively analysed. The patients were divided into an infected group and a noninfected group according to the occurrence of intracranial infection. The detailed clinical data of the two groups were collected. Univariate and multivariate logistic regression was used to analyse the risk factors for intracranial infection after NTPAR.

RESULTS

Among the 387 surgical patients, 32 patients (8.27%) were in the intracranially infected group and 355 patients (91.73%) were in the noninfected group. The results of the univariate analysis suggested that age > 45 years, tumour size > 1 cm, operation time > 240 min, blood loss > 400 ml, Kelly Grade of cerebrospinal fluid (CSF) leakage > Grade 2, postoperative CSF leakage, lumbar cistern drainage and blood transfusion were the influencing factors for postoperative intracranial infection, while the results of multivariate logistic regression analysis implied that intraoperative CSF leakage (Kelly Grade > 2) and postoperative CSF leakage were independent influencing factors for intracranial infection after NTPAR, and perioperative use of antibiotics was an independent protective factor for postoperative intracranial infection.

CONCLUSIONS

There are a variety of risk factors for intracranial infection after NTPAR, which indicates that it is necessary to develop different repair strategies for CSF leakage according to the Kelly Grade, timely treatment of postoperative CSF leakage and perioperative use of antibiotics. These measures have been shown to effectively reduce the probability of intracranial infection after NTPAR.

Diagnostic, monitoring, and prognostic value of combined detection of lactate dehydrogenase, β2-transferrin, and interleukin-10 for acute intracranial infections

OBJECTIVE

To investigate the value of the combined detection of lactate dehydrogenase (LDH), β2-transferrin (β-2Tf), and interleukin-10 (IL-10) for identification of acute intracranial infections such as meningitis.

METHODS

A total of 103 patients were placed in the suppurative meningitis group (SMG), 124 patients in the viral meningitis group (VMG). Another 86 patients without any infectious diseases of the central nervous system constituted the control group (CG). The levels of LDH and β-2Tf in the cerebrospinal fluid were determined by enzymatic methods; IL-10 expression was measured by ELISA. The correlation between infection and the LDH, β-2Tf, and IL-10 levels was analyzed by linear correlation analysis, and ROC curve analysis was applied to determine the diagnostic value of combined detection of LDH, β-2Tf, and IL-10 levels for intracranial infections.

RESULTS

LDH, β-2Tf, and IL-10 levels negatively correlated with the treatment time in both the SMG (r = -0.52, -0.97, and -0.24, respectively, P < 0.01) and VMG (r = -0.70, -0.91, and -0.25, respectively, P < 0.01). Sensitivity and specificity of combined detection of LDH, β-2Tf, and IL-10 for the diagnosis of SM was 80.47% and 75.33%, respectively, while those for VM were 84.24% and 79.24%, respectively.

CONCLUSION

Combined detection is an excellent indicator for the diagnosis and treatment of intracranial infections.

Treatment of Severe Acute Bacterial Keratitis in Rabbits Using Continuous Topical Ocular Instillation with Norvancomycin

Purpose

Efficacy of norvancomycin (NVCM) through continuous topical ocular instillation drug delivery (CTOIDD) system for treating severe acute bacterial keratitis infection with Staphylococcus aureus was investigated.

Methods

Rabbits with bacterial keratitis were treated using CTOIDD with NVCM (n=13), topical NVCM eye drops (n=11), and CTOIDD with saline (n=8). Clinical signs of keratitis in all groups were assessed consecutively for a week. Bacterial quantification of excised corneas was counted on the fourth and eighth days. Histopathologic examinations were performed to assess inflammatory cell infiltration on the eighth day.

Results

All signs of bacterial keratitis were alleviated in CTOIDD with NVCM according to criteria, and the CTOIDD-NVCM group had significantly less inflammation than CTOIDD-saline (p<0.05), and eye drop-NVCM (p<0.05). Two eyes in the eye drop-NVCM group, four eyes in the CTOIDD-saline group had corneal perforation (CP), while none of the rabbits showed CP in the CTOIDD-NVCM group. Bacterial counts were significantly less in the CTOIDD with NVCM group in comparison to the eye drop-NVCM (p<0.05), and CTOIDD-saline (p<0.05) groups. Severe inflammation and marked inflammatory cell infiltration were found in histopathologic examinations in the CTOIDD-saline and eye drop-NVCM groups, while significantly less inflammation was documented in the CTOIDD-NVCM (p<0.05) group.

Conclusion

CTOIDD with NVCM effectively reduced the severity and treated acute bacterial S. aureus keratitis infection in a rabbit model. The presented approach of CTOIDD with NVCM appears to be a promising therapeutic approach for severe acute bacterial keratitis.

Population Pharmacokinetics and Pharmacodynamics of Norvancomycin in Children With Malignant Hematological Disease

Knowledge of pharmacokinetic (PK) behavior of norvancomycin (NVCM) in pediatric patients is lacking, which leads to empirical therapy in clinical practice. This study developed a population PK model of children aged 0-15 years; 112 opportunistic samples in total from 90 children were analyzed. The stability and prediction of the final model were evaluated by goodness-of-fit plots, nonparametric bootstrap, visual predictive check, and normalized prediction distribution errors. The PKs of NVCM in children was described by a 2-compartment model with first-order elimination along with body weight and estimated glomerular filtration rate as significant covariates on clearance. The population typical values of the PK parameters were as follows: clearance 0.12 L/kg/h, central compartment distribution volume 0.17 L/kg, peripheral compartment distribution volume 0.38 L/kg, and intercompartmental clearance 0.35 L/kg/h. Logistic analysis showed that the ratio of area under the concentration-time curve over 24 hours (AUC_0-24 ) to minimum inhibitory concentration (MIC) had the strongest correlation with clinical efficacy, and at least 80% clinical efficiency could be achieved when AUC_0-24 /MIC ≥ 221.06 was defined as the target. Monte Carlo simulation results suggested that a higher dose was required for this pediatric population in order to reach the target. The dosing regimen was optimized based on the final model. A population PK model of NVCM was first characterized in children with hematologic malignancy, and an evidence-based approach for NVCM dosage individualization was provided.

Sequential intraventricular injection of tigecycline and polymyxin B in the treatment of intracranial Acinetobacter baumannii infection after trauma: a case report and review of the literature

BACKGROUND

Intracranial infection after craniotomy is one of the most serious postoperative complications, especially multidrug-resistant (MDR) or extensively drug-resistant (XDR) bacterial meningitis, and strongly affects the prognosis of patients. Current treatment experience regarding these infections is scarce.

CASE PRESENTATION

We report a case of severe intracranial infection of XDR Acinetobacter baumannii (A. baumannii) that was treated by intravenous (IV) injection, sequential intraventricular (IVT) injection of tigecycline and polymyxin B, and other anti-infective drugs. Good results were obtained, and the patient was eventually discharged from the hospital. This case is characterized by intracranial infection.

CONCLUSIONS

The polymyxin B IV + IVT pathway is an ideal treatment strategy for XDR A. baumannii. The tigecycline IVT pathway is also a safe treatment option.

Comparative Assessment of Distribution Characteristics and Ocular Pharmacokinetics of Norvancomycin Between Continuous Topical Ocular Instillation and Hourly Administration of Eye Drop

Background

The aim of this study was to compare the distribution characteristics and ocular pharmacokinetics of norvancomycin (NVCM) in ocular tissues of the anterior segment between continuous topical ocular instillation and hourly administration of eye drop in rabbits.

Methods

Sixty rabbits were randomly divided into two groups: continuous topical ocular instillation drug delivery (CTOIDD) group and eye drop (control) group. In the CTOIDD group, NVCM solution (50 mg/mL) was perfused to the ocular surface using the CTOIDD system at 2 mL/h up to 10 h and the same solution was administered at one drop (50 μL) per hour for 10 h in the control group. Animals (N=6 per time-point per group) were humanely killed at 2, 4, 6, 10, and 24 h to analyze their ocular tissues and plasma. The concentrations of NVCM in the conjunctiva, cornea, aqueous humour, iris, ciliary body and plasma were measured by HPLC with photodiode array detector. The pharmacokinetic parameters were calculated by Kinetica 5.1.

Results

The highest concentrations of NVCM for the CTOIDD group and control group were 2105.45±919.89 μg/g and 97.18±43.14 μg/g in cornea, 3033.92±1061.95 μg/g and 806.99±563.02 μg/g in conjunctiva, 1570.19±402.87 μg/g and 46.93±23.46 μg/g in iris, 181.94±47.11 μg/g and 15.38±4.00 μg/g in ciliary body, 29.78±4.90 μg/mL and 3.20±1.48 μg/mL in aqueous humour, and 26.89±5.57 μg/mL and 1.90±1.87 μg/mL in plasma, respectively. The mean NVCM levels significantly increased at all time-points in cornea, iris, and ciliary body (p<0.05) in the CTOIDD group. The AUC_0–24 values in the CTOIDD group were 27,543.70 μg·h/g in cornea, 32,514.48 μg·h/g in conjunctiva, 8631.05 μg·h/g in iris, 2194.36 μg·h/g in ciliary body and 343.9 μg·h/mL in aqueous humour, which were higher than for the eye drop group in all tissues.

Conclusion

Since continuous instillation of NVCM with CTOIDD could reach significantly higher concentrations and was sustained for a longer period compared with hourly administration of eye drop, CTOIDD administered NVCM could be a possible method to treat bacterial keratitis.

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Plasma and cerebrospinal fluid population pharmacokinetic modeling and simulation of meropenem after intravenous and intrathecal administration in postoperative neurosurgical patients

Combined intravenous and local intrathecal administration of meropenem in patients after craniotomy is widely used to treat intracranial infections. However, the optimal dosing regimen of meropenem has not been investigated, posing a risk to treatment efficacy. We aimed to identify significant factors associated with inter-individual variability in cerebrospinal fluid (CSF) pharmacokinetics of meropenem and to evaluate potential intravenous and intrathecal meropenem dosing regimens for the treatment of patients with intracranial infections. After the diagnosis of intracranial infection, 15 patients with an indwelling drain tube received intravenous and intrathecal administration of meropenem. Blood and cerebrospinal fluid (CSF) samples were obtained at the scheduled time to measure meropenem concentration. Plasma and CSF concentration-time data were fit simultaneously using a nonlinear mixed-effects modeling approach. A 3-compartmental model was selected to characterize the in vivo behavior of meropenem. Through population modeling, multiple covariates were tested about their impact on the meropenem pharmacokinetics. Considering CSF outflow via drain tube leading to a drug loss, the drug clearance in CSF (CL_CSF) was added to describe this drug loss. The covariate selection indicated that the drainage volume (mL/d) had a significant positive correlation with CL_CSF. Bootstrap and visual predictive check suggested a robust and reliable pharmacokinetic model was structured. The established final population model was useful to apply with simulation to identify meropenem dosing regimens for the treatment of patients with intracranial infections. With the goal of CSF concentrations exceeding the minimum inhibitory concentration during the therapy, we created a simple to use dosage regimen table to guide clinicians with drug dosing.

Optimal infusion rate in antimicrobial therapy explosion of evidence in the last five years

Background

Sporadic studies in antimicrobial therapy have evaluated the effects of infusion rates on therapeutic and economic outcomes, and new findings may challenge the regular infusion regimen.

Methods

Focusing on studies comparing the outcomes of different infusion regimens, the relevant literature was identified by searching PubMed, Web of Science, and Scopus from January 1, 2013 to March 1, 2018. Papers were finally chosen using a PRISMA flowchart.

Results

Antimicrobials with the superiority of prolonged infusion to standard infusion in terms of efficacy and safety include meropenem, doripenem, imipenem, cefepime, ceftazidime, piperacillin/tazobactam, linezolid, and vancomycin. The strategy of concomitantly reducing total daily dose and prolonging infusion time may cause treatment failure (eg, imipenem). Extended infusion of piperacillin/tazobactam has pharmacoeconomic advantage over standard infusion. Prolonged infusion of voriconazole is inferior to standard infusion because of lower efficacy caused by pharmacokinetic changes. Comparable outcomes following standard infusion and continuous infusion were observed with norvancomycin and nafcillin. Factors determining whether prolonged infusion has a benefit over standard infusion include MIC of bacterial pathogens, bacterial density, diagnosis, disease severity, total daily dose, and renal function.

Conclusion

To maximally preserve the effectiveness of current antimicrobials, effective interventions should be implemented to enhance the application of optimal infusion strategies. For reducing nephrotoxicity, prolonged infusion of meropenem is better than conventional infusion in neonates with Gram-negative late-onset sepsis, and continuous infusion of vancomycin is superior to intermittent infusion. For increasing efficacy, prolonged or continuous infusion of time-dependent antimicrobials (eg, meropenem, doripenem, imipenem, cefepime, ceftazidime, piperacillin/tazobactam, linezolid, and vancomycin) is an optimal choice. Nevertheless, such advantages may only be demonstrated in special clinical circumstances and special populations (eg, patients with a sequential organ failure assessment (SOFA) score≥9, respiratory tract infections, urinary or intra-abdominal infections, or infections caused by less susceptible pathogens would benefit from prolonged infusion of piperacillin/tazobactam).

Factors Influencing Norvancomycin Concentration in Plasma and Cerebrospinal Fluid in Patients After Craniotomy and Dosing Guideline: A Population Approach

PURPOSE

Antibacterial spectrum and activity of norvancomycin are comparable with vancomycin, and it has been widely used in China. Norvancomycin can penetrate into the cerebrospinal fluid (CSF) through the damaged blood-brain barrier in patients after craniotomy. Because higher inter-individual variability was observed, we aimed to identify factors related to drug concentration to guide clinicians with norvancomycin dosing.

METHODS

After craniotomy, patients with an indwelling catheter in the operational area/ventricle were intravenously administered norvancomycin. Venous blood and CSF specimens were collected at a scheduled time for measuring drug concentrations. Blood and CSF data were fitted simultaneously with the use of the nonlinear fixed-effects modeling method to develop the population pharmacokinetic model. Covariate analysis was applied to select candidate factors associated with pharmacokinetic parameters. A model-based simulation was performed to find optimized regimens for different subgroups of patients.

FINDINGS

A 3-compartmental model (central, peripheral, and CSF compartments) with 2 elimination pathways (drug elimination from the kidney and CSF outflow) was developed to characterize the in vivo process of norvancomycin. The covariate analysis identified that weight and drainage amount were strongly associated with the central volume and the drug clearance from CSF, respectively. Goodness-of-fit and model validation suggested that the proposed model was acceptable. A dosage regimen table was created for specific patient populations with different weights and drainage amounts to facilitate clinical application.

IMPLICATIONS

We identified 2 clinical markers associated with plasma and CSF concentrations. The proposed simulation may be useful to clinicians for norvancomycin dosing in this specific population with normal kidney function.

Pharmacokinetics and cerebrospinal fluid penetration of norvancomycin in Chinese adult patients

Norvancomycin is an antibiotic that has been approved for the treatment of infections caused by antibiotic-resistant Gram-positive bacteria and has been used in China for more than a decade. However, the cerebrospinal fluid (CSF) penetration of norvancomycin has not been evaluated. The aims of the study were (i) to investigate the pharmacokinetics and CSF penetration of norvancomycin in meningitis and non-meningitis patients and (ii) to recommend favourable dosing regimens in meningitis patients. Twenty adult patients (ten with meningitis and ten without meningitis) requiring norvancomycin treatment were enrolled. All patients received a norvancomycin regimen of 800 mg every 12 h. Blood and CSF samples were consecutively collected up to 12 h after the end of the fourth 60-min infusion. Norvancomycin concentrations both in serum and CSF were measured using a high-performance liquid chromatography (HPLC) assay. CSF penetration of norvancomycin was evaluated by calculating the CSF/serum ratio. Mean norvancomycin serum trough levels were 9.9 ± 1.44 µg/mL in patients with meningitis and 10.08 ± 1.12 µg/mL in patients without meningitis (P > 0.05). In addition, norvancomycin penetrated into the inflamed meninges, with mean CSF concentrations of 3.93-10.52 µg/mL and mean CSF/serum ratios of 0.18-0.43, both of which were significantly higher than in patients without meningitis (P <0.05). These results suggest that norvancomycin has higher CSF penetration in patients with meningitis compared with other groups and that norvancomycin is effective in treating patients with purulent meningitis at a comparably low dose.