Retrospective Evaluation of Drug-Drug Interactions With Erlotinib and Gefitinib Use in the Military Health System.

Background: Erlotinib and gefitinib are epidermal growth factor receptor-tyrosine kinase inhibitors approved for non-small cell lung cancer treatment by the US Food and Drug Administration. Drug-drug interactions (DDIs) with these agents are vague and poorly understood. Because DDIs can have an effect on clinical outcomes, we aimed to identify drugs that interact with erlotinib or gefitinib and describe their clinical manifestations. Methods: A retrospective analysis was performed on the health records of patients in the US Department of Defense Cancer Registry (retrieved September 2021), Comprehensive Ambulatory/Professional Encounter Records, and Pharmacy Data Transaction Service database (both retrieved May 2022). Patients' medical history, diagnoses, and demographics were extracted and analyzed for differences in adverse effects when these agents were used alone vs concomitantly with other prescription drugs. Patients' diagnoses and prescription drug use were extracted to compare completed vs discontinued treatment groups, identify medications commonly co-administered with erlotinib or gefitinib, and evaluate DDIs with antidepressants. Results: Of 387 patients using erlotinib, 264 completed treatments; 28 of 33 patients using gefitinib completed treatment. The P value for erlotinib discontinuation when used alone vs concomitantly was < .001, and the P value for gefitinib discontinuation was .06. Patients who took erlotinib or gefitinib concomitantly with a greater number of prescription drugs had a higher rate of treatment discontinuation than those who received fewer medications. Patients in the completed group received 1 to 75 prescription drugs, and those in the completed group were prescribed 3 to 103. Those who discontinued treatment had more diagnosed medical issues than those who completed treatment. Conclusions: This review cannot conclude that concomitant use with prescription drug(s) resulted in erlotinib or gefitinib discontinuation. There were no significant DDIs determined between erlotinib or gefitinib and antidepressants.

Stability for 6 months and accuracy of a specific enteral caffeine base preparation for a multisite clinical trial.

The 'Intermittent Hypoxia and Caffeine in Infants Born Preterm (ICAF)' study (NCT03321734) uses an extemporaneously compounded enteral caffeine base solution for its study drug. The primary aim of this report is to determine the stability of this specific enteral caffeine base preparation stored for up to 6 months and assess optimal storage temperature. To analyse stability, caffeine solutions were prepared and stored at 4°C and 25°C (room temperature). The caffeine concentrations were analysed over time using high-performance liquid chromatography (HPLC). To confirm the accuracy of compounded caffeine concentrations, study drug samples from three research pharmacies were analysed. Stability results showed that caffeine concentrations are within 5% of the expected concentration when stored for up to 6 months at room temperature. Our results also show that accurate caffeine concentrations were achieved by multiple research pharmacies.

Pre-clinical drug-drug interactions (DDIs) of gefitinib with/without losartan and selective serotonin reuptake inhibitors (SSRIs): citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, and venlafaxine.

Objective: To evaluate drug-drug interactions (DDIs) between gefitinib with/without losartan and selective serotonin reuptake inhibitors (SSRIs). Methods: In vitro supersomes were used to identify CYP isoenzymes (CYP1A2, 2C9, 2C19, 2D6, and 3A4) involved in drug metabolism, and in vitro pooled cryopreserved primary human hepatocytes were employed to investigate DDIs. Results: The isoenzymes that showed drug degradation are listed in parentheses beside the respective drug: gefitinib (CYP2D6, 3A4, 1A2, 2C9, and 2C19), losartan (CYP2C9 and 3A4), citalopram (CYP2D6, 2C19, 3A4, and 2C9), fluoxetine (CYP2D6, 2C9, and 2C19), fluvoxamine (CYP2D6, 2C9, and 2C19), paroxetine (CYP2D6, 3A4, and 2C9), sertraline (CYP2D6, 2C9, 2C19, 1A2, and 3A4), and venlafaxine (CYP2D6 and 2C19).DDIs from human hepatocytes assays revealed that gefitinib had significant metabolic changes in (1:1) combination with paroxetine or sertraline (p-value â€‹= â€‹0.042 and 0.025 respectively) and (1:1:1) combination with losartan and fluoxetine, fluvoxamine, paroxetine, or sertraline (p-value â€‹= â€‹0.009, 0.027, 0.048, and 0.037 respectively). Losartan showed significant changes in (1:1:1) combination with gefitinib and fluoxetine or sertraline (p-value â€‹= â€‹0.026 and 0.008 respectively). Fluoxetine, fluvoxamine, and paroxetine underwent significant changes in (1:1:1) combination with gefitinib and losartan (p-value â€‹= â€‹0.003, 0.022, and 0.046 respectively). Sertraline had significant changes within all combinations: DDIs with gefitinib alone and in combination with gefitinib and losartan (p-value â€‹= â€‹0.009 and 0.008 respectively). Citalopram and venlafaxine appeared to be unaffected by any combination. Conclusion: The study provides a clear proof-of concept for in vitro metabolic DDI testing. While identifying compounds by their inhibition potential can help better predict their metabolism, it cannot resolve problems that arise from DDIs since the overall degree of effectiveness is unknown. As shown in this study, gefitinib has been identified as a weak CYP2C19 and 2D6 inhibitor, however, gefitinib can have significant DDIs with sertraline. Furthermore, multiple drug combinations (1:1:1) can change the significance of previously determined DDIs in (1:1) combination. Thus, in vitro assays can potentially provide better guidance for multidrug regimens with minimal risk for DDIs.

Pre-clinical drug-drug interaction (DDI) of gefitinib or erlotinib with Cytochrome P450 (CYP) inhibiting drugs, fluoxetine and/or losartan.

OBJECTIVE: To evaluate drug-drug interactions (DDIs) between gefitinib or erlotinib with fluoxetine, and/or losartan. METHODS: Human pooled microsomes, supersomes, and cryopreserved human hepatocytes were used to monitor DDIs in vitro. RED (Rapid Equilibrium Dialysis) protein binding was employed to investigate other pharmacokinetics. RESULTS: Gefitinib is significantly metabolized by Cytochrome P450 (CYP) 2D6 and CYP3A4, with less than 80% of the drug remaining. Erlotinib is significantly metabolized by CYP3A4, CYP2D6, and CYP1A2. Although gefitinib and erlotinib were metabolized by the same CYP isoenzymes, the metabolites formed from degradation of the two drugs were different.Fluoxetine inhibited CYP2D6 and CYP3A4 metabolism of gefitinib with an IC50 of 65.12 ± 1.88 µM and 4.11 ± 2.26 µM, respectively. Fluoxetine also inhibited CYP2D6 and CYP3A4 metabolism of erlotinib with an IC50 of 7.06 ± 1.54 µM and 4.57 ± 1.22 µM, respectively.For hepatocytes, fluoxetine affected the metabolism of gefitinib or erlotinib, while losartan had no effect. Gefitinib and erlotinib inhibited the metabolism of fluoxetine and losartan. Two-drug combinations involving gefitinib or erlotinib with fluoxetine or losartan yielded insignificant (p-value ≥ 0.05) differences in metabolism. However, combinations involving three drugs yielded significant degrees of inhibition (p-value ≤ 0.05). Three drug combinations involving fluoxetine and losartan with gefitinib or erlotinib yielded significant degrees of inhibition of the metabolism of gefitinib, but not for that of erlotinib. CONCLUSION: As could be predicted by previous studies involving the inhibitory effect of fluoxetine on CYP3A4 and CYP2D6, and studies involving CYP metabolism of gefitinib and erlotinib, the tests performed here confirmed that fluoxetine has an inhibitory effect on metabolism of gefitinib or erlotinib by the main CYP isoenzymes involved. This study suggests a variable inhibitory effect of fluoxetine particularly on CYP2D6 activity towards gefitinib or erlotinib; erlotinib metabolism is less affected. Likewise, the combination of fluoxetine and losartan does not significantly affect hepatocyte metabolism of erlotinib, but does for that of gefitinib. The results presented in this study thus indicate a need for DDI assays to involve multiple drugs to properly study multidrug regimens.

Lead Optimization of Second-Generation Acridones as Broad-Spectrum Antimalarials.

The global impact of malaria remains staggering despite extensive efforts to eradicate the disease. With increasing drug resistance and the absence of a clinically available vaccine, there is an urgent need for novel, affordable, and safe drugs for prevention and treatment of malaria. Previously, we described a novel antimalarial acridone chemotype that is potent against both blood-stage and liver-stage malaria parasites. Here, we describe an optimization process that has produced a second-generation acridone series with significant improvements in efficacy, metabolic stability, pharmacokinetics, and safety profiles. These findings highlight the therapeutic potential of dual-stage targeting acridones as novel drug candidates for further preclinical development.

Discovery and Structural Optimization of Acridones as Broad-Spectrum Antimalarials.

Malaria remains one of the deadliest diseases in the world today. Novel chemoprophylactic and chemotherapeutic antimalarials are needed to support the renewed eradication agenda. We have discovered a novel antimalarial acridone chemotype with dual-stage activity against both liver-stage and blood-stage malaria. Several lead compounds generated from structural optimization of a large library of novel acridones exhibit efficacy in the following systems: (1) picomolar inhibition of in vitro Plasmodium falciparum blood-stage growth against multidrug-resistant parasites; (2) curative efficacy after oral administration in an erythrocytic Plasmodium yoelii murine malaria model; (3) prevention of in vitro Plasmodium berghei sporozoite-induced development in human hepatocytes; and (4) protection of in vivo P. berghei sporozoite-induced infection in mice. This study offers the first account of liver-stage antimalarial activity in an acridone chemotype. Details of the design, chemistry, structure-activity relationships, safety, metabolic/pharmacokinetic studies, and mechanistic investigation are presented herein.

Pre-clinical evaluation of CYP 2D6 dependent drug-drug interactions between primaquine and SSRI/SNRI antidepressants.

BACKGROUND: The liver-stage anti-malarial activity of primaquine and other 8-aminoquinoline molecules has been linked to bio-activation through CYP 2D6 metabolism. Factors such as CYP 2D6 poor metabolizer status and/or co-administration of drugs that inhibit/interact with CYP 2D6 could alter the pharmacological properties of primaquine. METHODS: In the present study, the inhibitory potential of the selective serotonin reuptake inhibitor (SSRI) and serotonin norepinephrine reuptake inhibitor (SNRI) classes of antidepressants for CYP 2D6-mediated primaquine metabolism was assessed using in vitro drug metabolism and in vivo pharmacological assays. RESULTS: The SSRI/SNRI classes of drug displayed a range of inhibitory activities on CYP 2D6-mediated metabolism of primaquine in vitro (IC50 1-94 µM). Fluoxetine and paroxetine were the most potent inhibitors (IC50 ~1 µM) of CYP 2D6-mediated primaquine metabolism, while desvenlafaxine was the least potent (IC50 ~94 µM). The most potent CYP 2D6 inhibitor, fluoxetine, was chosen to investigate the potential pharmacological consequences of co-administration with primaquine in vivo. The pharmacokinetics of a CYP 2D6-dependent primaquine metabolite were altered upon co-administration with fluoxetine. Additionally, in a mouse malaria model, co-administration of fluoxetine with primaquine reduced primaquine anti-malarial efficacy. CONCLUSIONS: These results are the first from controlled pre-clinical experiments that indicate that primaquine pharmacological properties can be modulated upon co-incubation/administration with drugs that are known to interact with CYP 2D6. These results highlight the potential for CYP 2D6-mediated drug-drug interactions with primaquine and indicate that the SSRI/SNRI antidepressants could be used as probe molecules to address the primaquine-CYP 2D6 DDI link in clinical studies. Additionally, CYP 2D6-mediated drug-drug interactions can be considered when examining the possible causes of human primaquine therapy failures.

Differential CYP 2D6 metabolism alters primaquine pharmacokinetics.

Primaquine (PQ) metabolism by the cytochrome P450 (CYP) 2D family of enzymes is required for antimalarial activity in both humans (2D6) and mice (2D). Human CYP 2D6 is highly polymorphic, and decreased CYP 2D6 enzyme activity has been linked to decreased PQ antimalarial activity. Despite the importance of CYP 2D metabolism in PQ efficacy, the exact role that these enzymes play in PQ metabolism and pharmacokinetics has not been extensively studied in vivo. In this study, a series of PQ pharmacokinetic experiments were conducted in mice with differential CYP 2D metabolism characteristics, including wild-type (WT), CYP 2D knockout (KO), and humanized CYP 2D6 (KO/knock-in [KO/KI]) mice. Plasma and liver pharmacokinetic profiles from a single PQ dose (20 mg/kg of body weight) differed significantly among the strains for PQ and carboxy-PQ. Additionally, due to the suspected role of phenolic metabolites in PQ efficacy, these were probed using reference standards. Levels of phenolic metabolites were highest in mice capable of metabolizing CYP 2D6 substrates (WT and KO/KI 2D6 mice). PQ phenolic metabolites were present in different quantities in the two strains, illustrating species-specific differences in PQ metabolism between the human and mouse enzymes. Taking the data together, this report furthers understanding of PQ pharmacokinetics in the context of differential CYP 2D metabolism and has important implications for PQ administration in humans with different levels of CYP 2D6 enzyme activity.

Comparison of MDCK-MDR1 and Caco-2 cell based permeability assays for anti-malarial drug screening and drug investigations.

INTRODUCTION: Malaria is a major health concern and affects over 300million people a year. Accordingly, there is an urgent need for new efficacious anti-malarial drugs. A major challenge in developing new anti-malarial drugs is to design active molecules that have preferable drug-like characteristics. These "drug-like" characteristics include physiochemical properties that affect drug absorption, distribution, metabolism, and excretion (ADME). Compounds with poor ADME profiles will likely fail in vivo due to poor pharmacokinetics and/or other drug delivery related issues. There have been numerous assays developed in order to pre-screen compounds that would likely fail in further development due to poor absorption properties including PAMPA, Caco-2, and MDCK permeability assays. METHODS: The use of cell-based permeability assays such as Caco-2 and MDCK serve as surrogate indicators of drug absorption and transport, with the two approaches often used interchangeably. We sought to evaluate both approaches in support of anti-malarial drug development. Accordingly, a comparison of both assays was conducted utilizing apparent permeability coefficient (Papp) values determined from liquid chromatography/tandem mass spectrometry (LC-MS) analyses. RESULTS: Both Caco-2 and MDCK permeability assays produced similar Papp results for potential anti-malarial compounds with low and medium permeability. Differences were observed for compounds with high permeability and compounds that were P-gp substrates. Additionally, the utility of MDCK-MDR1 permeability measurements was demonstrated in probing the role of P-glycoprotein transport in Primaquine-Chloroquine drug-drug interactions in comparison with in vivo pharmacokinetic changes. DISCUSSION: This study provides an in-depth comparison of the Caco-2 and MDCK-MDR1 cell based permeability assays and illustrates the utility of cell-based permeability assays in anti-malarial drug screening/development in regard to understanding transporter mediated changes in drug absorption/distribution.