Is Salivary Busulfan the Cause of Oral Mucositis and the Changes in Salivary Antioxidant Enzymes After Hematopoietic Cell Transplantation?

Limited Sampling Strategies for Estimating Busulfan Area Under the Concentration-Time Curve: Based on Peak and Trough Concentrations in Saliva

Therapeutic drug monitoring for busulfan is currently performed by multiple plasma sampling. Saliva is considered a noninvasive therapeutic drug monitoring matrix. This study aimed to investigate intravenous busulfan pharmacokinetics (PK) in plasma and saliva, and establish a limited sampling strategy (LSS) for predicting the area under the concentration-time curve from time zero to infinity in plasma (AUC0-∞,p) by using saliva samples. Therefore, the PK of busulfan was studied in 37 Chinese patients. Pearson correlation analysis was used to evaluate the correlation between the AUC of busulfan in plasma and saliva. LSS models were established by the multiple linear regression analysis. The prediction error, the mean prediction error, and the root mean square error were used to evaluate the predictive accuracy. The agreement between the predicted and observed AUC0-∞ in saliva was investigated by the intraclass correlation coefficient and Bland-Altman analysis. The accuracy and robustness of the models were evaluated by using the bootstrap procedure. The result of PK analysis 62.2% of patients (23/37) was within the target range of AUC0-∞,p . A good correlation between saliva and plasma busulfan AUC0-∞ was observed (r = 0.63, p < .01). The bias and precision of the models 7 and 13 were less than 15%. The intraclass correlation coefficient exceeded 0.9, and the limits of agreement were within ±15%. The 2-point LSS model in saliva is a convenient and desirable approach to predict the AUC0-∞ of 4 times daily intravenous busulfan in plasma, which can be used to design personalized dosing for busulfan.

Saliva as a noninvasive sampling matrix for therapeutic drug monitoring of intravenous busulfan in Chinese patients undergoing hematopoietic stem cell transplantation: A prospective population pharmacokinetic and simulation study

Therapeutic drug monitoring (TDM) of busulfan (BU) is currently performed by plasma sampling in patients undergoing hematopoietic stem cell transplantation (HSCT). Saliva samples are considered a noninvasive TDM matrix. Currently, no salivary population pharmacokinetics (PopPKs) model for BU available. This study aimed to develop a PopPK model that can describe the relationship between plasma and saliva kinetics in patients receiving intravenous BU. The performance of the model in predicting the area under the concentration-time curve at steady state (AUCss ) based on saliva samples is evaluated. Sixty-six patients with HSCT were recruited and administered 0.8 mg/kg BU intravenously. A PopPK model for saliva and plasma was developed using the nonlinear mixed effects model. Bayesian maximum a posteriori (MAP) optimization was used to estimate the model's predictive performance. Plasma and saliva PKs were adequately described with a one-compartment model and a scaled central compartment. Body surface area correlated positively with both clearance and apparent volume of distribution (Vd), whereas alkaline phosphatase correlated negatively with Vd. Simulations demonstrated that the percentage root mean squared prediction error and lower and upper limits of agreements reduced to 10.02% and -16.96% to 22.86% based on five saliva samples. Saliva can be used as an alternative matrix to plasma in TDM of BU. The AUCss can be predicted from saliva concentration by Bayesian MAP optimization, which can be used to design personalized dosing for BU.

Dental consensus on HSCT - Part II: dental Care during HSCT

During the state of immune vulnerability in hematopoietic stem cell transplantation (HSCT), the patient has an increased risk of developing a vast number of complications, including severe problems in the oral cavity. These situations require professional oral care to act in the diagnosis and treatment of these conditions, as well as to develop prevention protocols to minimize patient's complications. Oral mucositis, opportunistic infections, bleeding, specific microbiota, taste, and salivary alterations are complications that can occur during HSCT and interfere with various aspects, such as pain control, oral intake, nutrition, bacteremia and sepsis, days of hospitalization and morbidity. Several guidelines have been published to address the role of professional oral care during the HSCT, we describe a consensus regarding these recommendations.

Dried Plasma Spots and Oral Fluid as Alternative Matrices for Therapeutic Drug Monitoring of Busulfan: Analytical Method Development and Clinical Evaluation

BACKGROUND

Busulfan (BU) is an alkylating agent with a narrow therapeutic index and high intraindividual pharmacokinetic variability used in conditioning therapy for hematopoietic stem cell transplantation. Monitoring BU exposure during high-dose conditioning regimens is recommended and positively impacts outcomes. We aimed to develop, validate, and apply a ultra-high-performance liquid chromatography-mass spectrometry (MS)/MS assay to measure BU concentrations in oral fluid and dried plasma spots (DPS) as alternative matrices to plasma.

METHODS

We prepared plasma and oral fluid samples by protein precipitation and DPS after liquid extraction. We analyzed extracts using an LC-MS/MS system with an Acquity HSS T3 column in the positive electrospray ionization mode. The method was validated and applied to 79 paired plasma and oral fluid samples from 7 patients on BU conditioning treatment. DPS were prepared by pipetting plasma onto Whatman 903 paper. The correlation between BU in plasma, oral fluid, and DPS samples was evaluated.

RESULTS

Run time was 4.0 minutes. The assay was linear at 50-5000 ng mL-1 (r > 0.99), precise (1.9%-5.3% oral fluid and 1.8%-5.9% DPS), and accurate (98.1%-108.9% oral fluid and 93%-103.1% DPS). BU was stable in DPS at 23°C for 24 hours. BU levels in oral fluid (r = 0.927) and DPS (r = 0.982) were significantly correlated with plasma. Despite the good correlation, we found a wide variation between oral fluid and plasma levels. The area under curves (AUCs) calculated with oral fluid concentrations were 79.1%-167.1% of plasma AUCs. Bland-Altman plots found a better agreement for DPS, with AUCs estimated from corrected DPS levels at 83.1%-114.1% of plasma values.

CONCLUSIONS

We developed and validated a simple and fast ultra-high-performance liquid chromatography-MS/MS assay to measure BU in oral fluid and DPS. The results do not support the use of oral fluid as a matrix for routine therapeutic drug monitoring of BU. The AUC estimated from BU measurements in DPS was comparable to that in plasma, supporting the use of DPS in BU therapeutic drug monitoring as an alternative matrix, with adequate short-term stability and logistic advantages.