Pharmacokinetic approach in therapeutic monitoring of antineoplastic drugs and the impact on pharmacoeconomics: A systematic review

OBJECTIVES

Therapeutic drug monitoring aims to quantify the concentration of a drug in a biological matrix. In oncology, the therapeutic arsenal is vast and therapeutic drug monitoring optimizes treatment and reduces costs. This review will analyze the financial impact of therapeutic monitoring of anticancer drugs in healthcare institutions.

METHODS

Keywords were selected using Decs (MeSH). Through the Pubmed, Scopus, and Virtual Health Library (VHL) databases, 74 articles were found, of which 4 meet the inclusion criteria. Methodological quality and risk of bias were assessed according to the Research Triangle Institute Item Bank (RTI-Item Bank) scale.

KEY FINDINGS

Therapeutic drug monitoring is an important tool for dose reduction or dose increase due to toxicity and lack of response, respectively. The main barriers are associated costs and lack of cost-benefit data. An alternative is to use population pharmacokinetic models, measured plasma concentration(s) and relevant patient characteristics, estimated individual pharmacokinetic parameters, and predicted drug concentrations at any point in the dosing range.

CONCLUSIONS

Therapeutic drug monitoring is understood as a technology that adds costs to payers. Future studies should generate clinical evidence of population pharmacokinetics from therapeutic drug monitoring studies.

A pilot study of chemotherapy combinations in rats: Focus on mammary cancer treatment in female dogs

The use of combined chemotherapy is an essential alternative in treating breast cancer. However, knowledge of the pharmacokinetics of drugs is necessary to obtain maximum efficiency of the protocol and reduce adverse reactions. This study suggests for the first time the effect of the association of carboplatin with ivermectin and carboplatin with cyclophosphamide. This investigation was performed with 36 healthy Wistar rats, divided into four groups: group control, carboplatin (C), carboplatin preceded by ivermectin (C + IV), and carboplatin associated with cyclophosphamide (C + CI). Plasma concentrations quantification was performed using the High-Performance Liquid Chromatographic (HPLC) equipment with an Ultraviolet (UV) detector at eight different time points. Then, the animal was euthanized and necropsied. The bioanalytical method was validated for the two matrices (dogs and rats' plasma), with full validation in female dogs and partial validation in rats, as recommended by the EMA. In both matrices, the method was linear and reproducible. Here, we show the results in female rats' plasma. When comparing the experimental rats' groups (C; C + IV, and C + CI), there is a tendency to increase the bioavailability of carboplatin when used in association, a slight increase for C + IV and more evident to the C + CI group with an AUC rise higher than 2-fold (AUC0-∞ = 2983.61 for C; 4459.06 for C + CI; 7064.68 for C + CI min·mg·mL-1). The blood count, biochemistry profile, and histopathology of the organs revealed only alterations inherent to the metabolic effects of the drugs used. The carboplatin association with ivermectin appeared safe for this pilot group. We believe the carboplatin dose can be maintained without risk to the patient. However, in the carboplatin association with cyclophosphamide, a slight reduction in carboplatin's amount is suggested, seeking to avoid increased effects due to cyclophosphamide. Thus, studies with a more significant number per group must confirm the relevance of this pilot study.

Active Potential of Bacterial Cellulose-Based Wound Dressing: Analysis of Its Potential for Dermal Lesion Treatment

The use of innate products for the fast and efficient promotion of healing process has been one of the biomedical sector's main bets for lesion treatment modernization process. The aim of this study was to develop and characterize bacterial cellulose-based (BC) wound dressings incorporated with green and red propolis extract (2 to 4%) and the active compounds p-coumaric acid and biochanin A (8 to 16 mg). The characterization of the nine developed samples (one control and eight active wound dressings) evidenced that the mechanics, physics, morphological, and barrier properties depended not only on the type of active principle incorporated onto the cellulosic matrix, but also on its concentration. Of note were the results found for transparency (28.59-110.62T₆₀₀ mm^-1), thickness (0.023-0.046 mm), swelling index (48.93-405.55%), water vapor permeability rate (7.86-38.11 g m² day^-1), elongation (99.13-262.39%), and antioxidant capacity (21.23-86.76 μg mL^-1). The wound dressing based on BC and red propolis was the only one that presented antimicrobial activity. The permeation and retention test revealed that the wound dressing containing propolis extract presented the most corneal stratum when compared with viable skin. Overall, the developed wound dressing showed potential to be used for treatment against different types of dermal lesions, according to its determined proprieties.

Changes in tramadol enantioselective pharmacokinetics and metabolism in rats with experimental diabetes treated or not with insulin

This study aimed to investigate the impact of diabetes treated or not with insulin in the enantioselective pharmacokinetics of tramadol (trans-T) and its phase 1 metabolites O-desmethyltramadol (M1) and N-desmethyltramadol (M2). The CYP2D inhibitor quinidine was used to simulate the poor metabolizer phenotype. Male Wistar rats were divided into groups: control, quinidine (80-mg/kg quinidine intraperitoneally 4 h before trans-T), diabetic (45-mg/kg STZ i.v.), diabetes + insulin (2 IU/day insulin for 12 days), diabetes + quinidine and diabetes + insulin + quinidine. All animals (n = 6, per sampling time) received 20-mg/kg trans-T orally. The kinetic disposition of trans-T is enantioselective in control with higher AUC of (+)-trans-T than for its antipode. Quinidine reduced AUC ratios (+)-M1/(+)-trans-T and (-)-M1/(-)-trans-T compared to Control. Diabetes increased plasma concentrations of (+)-trans-T, (-)-trans-T, (+)-M1, (-)-M1 and (+)-M2 compared to control, but without changing AUC ratios M1/trans-T or M2/trans-T. Insulin reverted the effect of diabetes only for (-)-trans-T. The simulated diabetes in CYP2D poor metabolizers showed reduced metabolic ratios for M1 enantiomers. In conclusion, diabetes resulted in higher plasma concentrations of the active (+)-trans-T, (-)-trans-T and (+)-M1, suggesting down-regulation of CYP3A and OCT1. The glycemic control of diabetes by insulin reduces partially the impact of diabetes on trans-T pharmacokinetics.

Use of an Oral Busulfan Test Dose in Patients Undergoing Hematopoietic Stem Cell Transplantation Treated With or Without Fludarabine

This study investigated the importance of an oral test dose for busulfan (BU) dose adjustment before a conditioning regimen for hematopoietic stem-cell transplantation (HSCT) and the effect of fludarabine (FLU) on the oral BU pharmacokinetics evaluated after the fifth treatment dose (first BU dose on day 2 of treatment). Twenty-eight patients treated with oral BU (1 mg/kg every 6 hours for 4 days) were divided into 2 groups according to the concomitant administration of FLU (n = 15; 30 mg/m² for 5 days) or subsequent administration of cyclophosphamide (CY) (n = 13; 60 mg/kg for 2 days). On the day prior to the beginning of the conditioning regimen, blood samples were collected (0-6 hours) after administration of an oral BU test dose of 0.25 mg/kg. Busulfan was quantified in plasma samples by LC-MS/MS, and the pharmacokinetic parameters were calculated using WinNonlin software. Blood samples were collected between the fifth and sixth treatment dose to confirm the mean plasma steady-state concentration (C_ss ) of BU. The AUC_0-6 and apparent clearance of BU did not differ (P < .05) between the groups receiving FLU and CY. In 81% of the patients who received BU doses adjusted based on the test dose (n = 21), the C_ss was within the target range of 600-900 ng/mL. No association was observed between BU AUC_0-6 and clinical outcome in the study group (n = 28). The results suggest that in concomitant administration of FLU and BU during conditioning regimens for HSCT, changes in BU dose should be considered only after the administration of the fifth BU dose.

Influence of experimental diabetes and insulin treatment on the enantioselective pharmacokinetics of mexiletine and its metabolites

This study evaluates the influence of streptozotocin-induced diabetes on the kinetic disposition and metabolism of mexiletine (MEX) enantiomers in rats. Animals in the control (n = 6 for each blood collection time), diabetic (single intravenous dosage of 45 mg·(kg body mass)(-1) of streptozotocin), and insulin-treated groups (diabetic rats treated daily with 2 IU insulin) received by gavage a single dose of 10 mg·(kg body mass)(-1) racemic MEX. MEX enantiomers and the metabolites hydroxymethylmexiletine (HMM) and p-hydroxymexiletine PHM) were analyzed by LC-MS/MS. Statistical analysis was based on a serial sacrifice design, and parameter estimation was performed using a Bayesian modeling procedure. Area under the curve (AUC) for the (-)-(R) enantiomers of MEX, HMM, and PHM did not differ between the control and diabetic groups. However, AUC for (+)-(S)-MEX and (+)-(S)-HMM were lower in the diabetic than in the control group. Insulin treatment recovered glucose levels to normal and the (+)-(S)-MEX AUC and (+)-(S)-HMM AUC became similar to the AUCs observed in the nondiabetic animals.