Pharmacokinetics of gefitinib in humans: The influence of gastrointestinal factors

Enhanced Bioavailability and Reduced Variability of Dasatinib and Sorafenib with a Novel Amorphous Solid Dispersion Technology Platform

Despite clinical advances with protein kinase inhibitors (PKIs), oral administration of many PKIs is associated with highly variable plasma exposure and a narrow therapeutic window. We developed a novel hybrid nanoparticle-amorphous solid dispersion (ASD) technology platform consisting of an amorphous PKI embedded in a polymer matrix. The technology was used to manufacture immediate-release formulations of 2 tyrosine kinase inhibitors (TKIs), dasatinib and sorafenib. Our primary objective was to improve the absorption properties and reduce the pharmacokinetic (PK) variability of each TKI. The PKs of XS004 (dasatinib-ASD, 100 mg tablet) and XS005 (sorafenib-ASD, 2 × 50 mg capsules) were compared with their crystalline formulated reference drugs (140 mg of dasatinib-reference and 200 mg of sorafenib-reference). The in vitro biopharmaceutics of dasatinib-ASD and XS005-granulate showed sustained increased solubility in the pH range 1.2-8.0 compared to their crystalline references. In vivo, XS004 was bioequivalent at a 30% lower dose and showed increased absorption and bioavailability, with 2.1-4.8 times lower intra- and intersubject variability compared to the reference. XS005 had an increased absorption and bioavailability of 45% and 2.2-2.8 times lower variability, respectively, but it was not bioequivalent at the investigated dose level. Taken together, the formulation platform is suited to generate improved PKI formulations with consistent bioavailability and a reduced pH-dependent absorption process.

Gefitinib-resveratrol Cocrystal with Optimized Performance in Dissolution and Stability

Gefitinib (GEF) is an anti-tumor oral solid formulation with a superior advantage for lung tumors. However, it has poor aqueous solubility which limits its utility in vivo. Herein, a novel cocrystal (GEF-RES) assembled by GEF and RES (Resveratrol) has been successfully prepared and comprehensively characterized by differential scanning calorimetry, thermogravimetric analysis, Raman spectroscopy and powder X-ray diffraction. A single-crystal structure of the GEF-RES cocrystal was solved and illustrated in detail. In aqueous hydrochloric acid, the GEF-RES cocrystal showed that the maximum concentration of GEF was slightly higher than that of raw GEF. Furthermore, the thermal and physical stability of the GEF-RES cocrystal were also evaluated in this paper. The enhanced solubility and excellent solid-state stability results may provide new potential to the application of key GEF in clinical.

Gefitinib Inhibits Rifampicin-Induced CYP3A4 Gene Expression in Human Hepatocytes

During multidrug combination chemotherapy, activation of the nuclear receptor and the transcription factor human pregnane xenobiotic receptor (hPXR) has been shown to play a role in the development of chemoresistance. Mechanistically, this could occur due to the cancer drug activation of hPXR and the subsequent upregulation of hPXR target genes such as the drug metabolism enzyme, cytochrome P450 3A4 (CYP3A4). In the context of hPXR-mediated drug resistance, hPXR antagonists would be useful adjuncts to PXR-activating chemotherapy. However, there are currently no clinically approved hPXR antagonists in the market. Gefitinib (GEF), a tyrosine kinase inhibitor used for the treatment of advanced non-small-cell lung cancer and effectively used in combinational chemotherapy treatments, is a promising candidate owing to its hPXR ligand-like features. We, therefore, investigated whether GEF would act as an hPXR antagonist when combined with a known hPXR agonist, rifampicin (RIF). At therapeutically relevant concentrations, GEF successfully inhibited the RIF-induced upregulation of endogenous CYP3A4 gene expression in human primary hepatocytes and human hepatocells. Additionally, GEF inhibited the RIF induction of hPXR-mediated CYP3A4 promoter activity in HepG2 human liver carcinoma cells. The computational modeling of molecular docking predicted that GEF could bind to multiple sites on hPXR including the ligand-binding pocket, allowing for potential as a direct antagonist as well as an allosteric inhibitor. Indeed, GEF bound to the ligand-binding domain of the hPXR in cell-free assays, suggesting that GEF directly interacts with the hPXR. Taken together, our results suggest that GEF, at its clinically relevant therapeutic concentration, can antagonize the hPXR agonist-induced CYP3A4 gene expression in human hepatocytes. Thus, GEF could be a potential candidate for use in combinational chemotherapies to combat hPXR agonist-induced chemoresistance. Further studies are warranted to determine whether GEF has sufficient hPXR inhibitor abilities to overcome the hPXR agonist-induced chemoresistance.

Solid Dispersions of Gefitinib Prepared by Spray Drying with Improved Mucoadhesive and Drug Dissolution Properties

Gefitinib is a tyrosine kinase inhibitor that is intended for oral administration yet suffers poor bioavailability along with undesirable side effects. To enhance its solubility and allow colon targeting, gefitinib (ZD) and blends of different ratios of polymers (ternary dispersion) were prepared in organic solution, and solid dispersions were generated employing the spray drying (SD) technique. The methylmethacrylate polymer Eudragit S 100 was incorporated for colon targeting; polyvinylpyrrolidone (PVP) and hydroxypropyl methyl cellulose (HPMC) were utilised to improve the solubility of ZD. SEM, DSC, XRPD, FT-IR, dissolution and cytotoxicity studies were undertaken to characterise and evaluate the developed formulations. SEM images revealed that the rod-shaped crystals of ZD were transformed into collapsed spheres with smaller particle size in the spray-dried particles. DSC, FTIR and XRPD studies showed that ZD loaded in the spray-dried dispersions was amorphous. ZD dissolution and release studies revealed that while a significant (P < 0.05) increase in the ZD dissolution and release was observed from HPMC-based solid dispersion at pH 7.2 (up to 95% in 15 h), practically no drug was released at pH 1.2 and pH 6.5. Furthermore, the HPMC-based solid dispersions displayed enhanced mucoadhesive properties compared with PVP-based ones. Interestingly, cell viability studies using the neutral red assay showed that PVP and HPMC-based solid dispersions had no additional inhibitory effect on Caco-2 cell line compared to the pure drug.

p28-functionalized PLGA nanoparticles loaded with gefitinib reduce tumor burden and metastases formation on lung cancer

Lung cancer is still the main cause of cancer-related deaths worldwide. Its treatment generally includes surgical resection, immunotherapy, radiotherapy, and chemo-targeted therapies such as the application of tyrosine kinase inhibitors. Gefitinib (GEF) is one of them, but its poor solubility in gastric fluids weakens its bioavailability and therapeutic activity. In addition, like all other chemotherapy treatments, GEF administration can cause damage to healthy tissues. Therefore, the development of novel GEF delivery systems to increase its bioavailability and distribution in tumor site is highly demanded. Herein, an innovative strategy for GEF delivery, by functionalizing PLGA nanoparticles with p28 (p28-NPs), a cell-penetrating peptide derived from the bacterial protein azurin, was developed. Our data indicated that p28 potentiates the selective interaction of these nanosystems with A549 lung cancer cells (active targeting). Further p28-NPs delivering GEF (p28-NPs-GEF) were able to selectively reduce the metabolic activity of A549 cells, while no impact was observed in non-tumor cells (16HBE14o-). In vivo studies using A549 subcutaneous xenograft showed that p28-NPs-GEF reduced A549 primary tumor burden and lung metastases formation. Overall, the design of a p28-functionalized delivery nanosystem to effectively penetrate the membranes of cancer cells while deliver GEF could provide a new strategy to improve lung cancer therapy.

Using naso- and oro-intestinal catheters in physiological research for intestinal delivery and sampling in vivo: practical and technical aspects to be considered

Intestinal catheters have been used for decades in human nutrition, physiology, pharmacokinetics, and gut microbiome research, facilitating the delivery of compounds directly into the intestinal lumen or the aspiration of intestinal fluids in human subjects. Such research provides insights about (local) dynamic metabolic and other intestinal luminal processes, but working with catheters might pose challenges to biomedical researchers and clinicians. Here, we provide an overview of practical and technical aspects of applying naso- and oro-intestinal catheters for delivery of compounds and sampling luminal fluids from the jejunum, ileum, and colon in vivo. The recent literature was extensively reviewed, and combined with experiences and insights we gained through our own clinical trials. We included 60 studies that involved a total of 720 healthy subjects and 42 patients. Most of the studies investigated multiple intestinal regions (24 studies), followed by studies investigating only the jejunum (21 studies), ileum (13 studies), or colon (2 studies). The ileum and colon used to be relatively inaccessible regions in vivo. Custom-made state-of-the-art catheters are available with numerous options for the design, such as multiple lumina, side holes, and inflatable balloons for catheter progression or isolation of intestinal segments. These allow for multiple controlled sampling and compound delivery options in different intestinal regions. Intestinal catheters were often used for delivery (23 studies), sampling (10 studies), or both (27 studies). Sampling speed decreased with increasing distance from the sampling syringe to the specific intestinal segment (i.e., speed highest in duodenum, lowest in ileum/colon). No serious adverse events were reported in the literature, and a dropout rate of around 10% was found for these types of studies. This review is highly relevant for researchers who are active in various research areas and want to expand their research with the use of intestinal catheters in humans in vivo.

The Pharmacokinetics of Gefitinib in a Chinese Cancer Population Group: A Virtual Clinical Trials Population Study

Gefitinib, a selective inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase, is used to treat non-small-cell lung cancer (NSCLC). Lung cancer rates are high in China and are expected to increase over the next decade. CYP 2D6 intermediate metaboliser (IM) phenotypes are more prevalent in the Chinese population compared to Caucasians; the increased risk of drug-drug interactions (DDI) with chemotherapy polypharmacy may lead to different clinical pharmacokinetics outcomes for Chinese patients. This study developed and validated a virtual Chinese cancer population for the pragmatic assessment of gefitinib DDI as a victim drug in Chinese and Caucasian cancer populations. When assessing the impact of 2D6 phenotypes on bupropion mediated CYP 2D6 DDI in Chinese cancer population, we found that AUC increased by at least 60% in extensive metabolizers (EM) and 30% in IM. As a result, fmCYP2D6 was reduced by 15% in IM in the presence of bupropion, translating into > 70% of EM subjects and > 48% of IM subjects with trough concentrations at steady state (Ctrough,ss) below the gefitinib target trough level. The PBPK model predicted that a 500 mg once daily dose in both EM and IM subjects successfully reduced the percent of subjects below the Ctrough,ss. Such changes in Ctrough,ss warrant further investigation and highlight the ability of pharmacokinetic modelling to investigate populations that may be difficult to recruit for traditional clinical studies.

Investigating the Impact of Crohn's Disease on the Bioaccessibility of a Lipid-Based Formulation with an In Vitro Dynamic Gastrointestinal Model

The aim of the study was to investigate the impact of Crohn's disease (CD) on the performance of a lipid-based formulation of ciprofloxacin in a complex gastrointestinal simulator (TIM-1, TNO) and to compare the luminal environment in terms of bile salt and lipid composition in CD and healthy conditions. CD conditions were simulated in the TIM-1 system with a reduced concentration of porcine pancreatin and porcine bile. The bioaccessibility of ciprofloxacin was similar in simulated CD and healthy conditions considering its extent as well as its time course in the jejunum and ileum filtrate. Differences were observed in terms of the luminal concentration of triglycerides, monoglycerides, and fatty acids in the different TIM-1 compartments, indicating a reduction and delay in the lipolysis of formulation excipients in CD. The quantitative analysis of bile salts revealed higher concentrations for healthy conditions (standard TIM-1 fasted-state protocol) in the duodenum and jejunum TIM-1 compartments compared to published data in human intestinal fluids of healthy subjects. The reduced concentrations of bile salts in simulated CD conditions correspond to the levels observed in human intestinal fluids of healthy subjects in the fasted state.A lipidomics approach with ultra performance liquid chromatography (UPLC)/mass spectrometry (MS) has proven to be a time-efficient method to semiquantitatively analyze differences in fatty acid and bile salt levels between healthy and CD conditions. The dynamic luminal environment in CD and healthy conditions after administration of a lipid-based formulation can be simulated using the TIM-1 system. For ciprofloxacin, an altered luminal lipid composition had no impact on its performance indicating a low risk of altered performance in CD patients.

Comprehensive identification, fragmentation pattern, and metabolic pathways of gefitinib metabolites via UHPLC-Q-TOF-MS/MS: in vivo study of rat plasma, urine, bile, and faeces

Gefitinib, the first approved inhibitor for oral epidermal growth factor receptor (EGFR), has been proved to be effective in non-small cell lung cancer with EGFR mutation. However, there are many metabolites of gefitinib that have not been identified in vivo. This study aims to identify the metabolites of gefitinib and its metabolic pathways in rats using ultra-high-performance liquid chromatography coupled with a quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) detector. Protein precipitation, solid-phase and ultrasonic extraction were used for the pre-treatment of plasma, urine, bile and faeces samples. In this study, a total of 28 compounds were identified in rat plasma, 29 in bile, 20 in urine and 16 in faeces. 20 new compounds were firstly reported as metabolites of gefitinib. Reduction, hydroxylation, dealkylation and dehalogenation were the major metabolic pathways in phase I. For phase II, the main pathways were sulphate and glucuronide conjugation. The fragment ions of gefitinib and its metabolites were usually generated via the fracture of C₁-O bond of propoxy on the C₆ position of aniline quinazoline ring. The results may be valuable and important for understanding the metabolic process of gefitinib in clinical application and drug safety.

Epithelial Transfer of the Tyrosine Kinase Inhibitors Erlotinib, Gefitinib, Afatinib, Crizotinib, Sorafenib, Sunitinib, and Dasatinib: Implications for Clinical Resistance

Simple Summary

Tyrosine kinase inhibitors (TKIs) specifically inhibit phosphorylation of signaling pathways of cancer cells, thereby inhibiting their growth. They are characterized by a poor solubility and high protein binding, leading to a large variability in gut uptake after oral administration and variation in the clinical efficacy. We used the CaCo2 gut epithelial model to characterize the gut absorption of 7 TKIs and observed a large variation in apical/basolateral (mimicking gut/blood) transfer, with 4 TKIs showing a negative and 3 a neutral transfer. A highly negative transfer may lead to pharmacokinetic resistance. Intracellular uptake of TKIs was high for sunitinib and crizotinib, intermediate for gefitinib, dasatinib and sorafenib, low for afatinib and not detectable for erlotinib. These properties may explain a high red blood cell to plasma ratio for most TKIs investigated. Although TKIs are poorly absorbed the latter property may compensate for this.

Abstract

Background: tyrosine kinase inhibitors (TKIs) inhibit phosphorylation of signaling proteins. TKIs often show large variations in the clinic due to poor pharmacology, possibly leading to resistance. We compared gut absorption of inhibitors of epidermal growth factor receptor (erlotinib, gefitinib, and afatinib), ALK-cMET (crizotinib), PDGFR/BCR-Abl (dasatinib), and multikinase inhibitors (sunitinib and sorafenib). In clinical samples, we measured the disposition of each compound within various blood compartments. Methods: we used an optimized CaCo2 gut epithelial model to characterize 20 µM TKI absorption. The apical/basolateral transfer is considered to represent the gut/blood transfer. Drugs were measured using LC-MS/MS. Results: sorafenib and sunitinib showed the highest apical/basolateral transfer (Papp 14.1 and 7.7 × 10⁻⁶ cm/s, respectively), followed by dasatinib (3.4), afatinib (1.5), gefitinib (0.38), erlotinib (0.13), and crizotinib (n.d.). However, the net absorptions for dasatinib, afatinib, crizotinib, and erlotinib were highly negative (efflux ratios >5) or neutral/negative, sorafenib (0.86), gefitinib (1.0), and sunitinib (1.6). A high negative absorption may result in resistance because of a poor exposure of tissues to the drug. Accumulation of the TKIs at the end of the transfer period (A->B) was not detectable for erlotinib, very low for afatinib 0.45 pmol/μg protein), followed by gefitinib (0.79), dasatinib (1.1), sorafenib (1.65), and crizotinib (2.11), being highest for sunitinib (11.9). A similar pattern was found for accumulation of these drugs in other colon cell lines, WiDr and HT29. In clinical samples, drugs accumulated consistently in red blood cells; blood to plasma ratios were all >3 (sorafenib) or over 30 for erlotinib. Conclusions: TKIs are consistently poorly absorbed, but accumulation in red blood cells seems to compensate for this.

Preconcentration and Detection of Gefitinib Anti-Cancer Drug Traces from Water and Human Plasma Samples by Means of Magnetic Nanoparticles

Along of widespread application of anti-cancer drug Gefitinib (GEF), it appears in human body fluids as well as clinical wastewater. Consequently, a reliable and easy-to-adapt detection technique is of essential importance to quantify the drug in different media. The extraction and quantitative detection of anti-cancer drug Gefinitib (GEF) is demonstrated based on a straightforward and efficient magnetic nanoparticle-assisted preconcentration route from water and human plasma samples. Iron oxide magnetic nanoparticles (Fe₃O₄) have been prepared with an average particle size of 15 nm and utilized as extractible adsorbents for the magnetic solid-phase extraction (MSPE) of GEF in aqueous media. The method is based on MSPE and preconcentration of GEF followed by High-Performance Liquid Chromatography-Ultraviolet Detection (HPLC-UV). The yield of GEF extraction under the optimum MSPE conditions were 94% and 87% for water and plasma samples, respectively. The chromatographic separation was carried out isocratically at 25 °C on a Phenomenex C8 reversed phase column (150 mm × 4.6 mm, with 5 µm particle size). The proposed method was linear over concentration ranges of 15.0–300.0 and 80.0–600.0 ng/mL for water and plasma samples with limits of detection of 4.6 and 25.0 ng/mL in a respective order. Relative standard deviations (%RSD) for intra-day and inter-day were 0.75 and 0.94 for water samples and 1.26 and 1.70 for plasma samples, respectively. Using the magnetic nanoparticles (MNPs) as loaded drug-extractors made the detection of the anti-cancer drug environmentally friendly and simple and has great potential to be used for different drug-containing systems.

FDA- and EMA-Approved Tyrosine Kinase Inhibitors in Advanced EGFR-Mutated Non-Small Cell Lung Cancer: Safety, Tolerability, Plasma Concentration Monitoring, and Management

Non-small-cell lung cancer (NSCLC) is the most common form of primary lung cancer. The discovery of several oncogenic driver mutations in patients with NSCLC has allowed the development of personalized treatments based on these specific molecular alterations, in particular in the tyrosine kinase (TK) domain of the epidermal growth factor receptor (EGFR) gene. Gefitinib, erlotinib, afatinib, and osimertinib are TK inhibitors (TKIs) that specifically target EGFR and are currently approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) as first line treatment for sensitive EGFR-mutant patients. However, these four drugs are associated with severe adverse events (AEs) that can significantly impact patient health-related quality of life and patient monitoring. EGFR-TKIs are commonly used together with other types of medication that can substantially interact. Here, we review approaches used for the management of TKI-AEs in patients with advanced NSCLC to promote the benefits of treatments and minimize the risk of TKI treatment discontinuation. We also consider potential TKI–drug interactions and discuss the usefulness of plasma concentration monitoring TKIs based on chromatographic and mass spectrometry approaches to guide clinical decision-making. Adjusting the most appropriate therapeutic strategies and drug doses may improve the performance therapy and prognosis of patients with advanced EGFR-mutated NSCLC.

Association of Variability and Pharmacogenomics With Bioequivalence of Gefitinib in Healthy Male Subjects

Objective: The aim of the study was to explore the association of pharmacokinetic variability and pharmacogenomics with the bioequivalence of orally administered gefitinib (Iressa®, AstraZeneca) provided by three sponsors in healthy subjects. Methods: The study designs were randomized, open-label, and two-period crossover studies in both fasting and fed healthy subjects. In one fasting study, the sample size was enlarged from 30 to 60 for the failing study. Each study subject received a 250-mg gefitinib tablet with a 21-day washout. The plasma concentrations were measured using LC-MS/MS, and pharmacokinetic parameters were determined by noncompartmental methods. Genetic analyses of CYP3A4, CYP3A5, and CYP2D6 alleles were carried out by the polymerase chain reaction (PCR). Results: Two hundred and sixty healthy male subjects were enrolled. The median maximum plasma concentration (T_max) was 4-5 h, and the mean elimination half-life (t_1/2) was 18-26 h. The maximum plasma concentration (C_max) and area under the curve (AUC) increased but T_max and t_1/2 were unaffected by the intake of high-fat food. Three fed and two fasting studies achieved a plausible bioequivalence. The intake of high-fat food decreased the intra-subject variability significantly. In addition, CYP2D6 was associated with gefitinib exposure and may contribute to the high inter-subject variability, but it did not influence the bioequivalence result. Conclusions: Gefitinib is well tolerated, and the bioequivalence is easier to achieve under fed conditions compared to fasting conditions. The 90% confidence interval (CI) of geometric mean ratio (GMR) can be narrowed when the sample size is enlarged without changing the formulation-related technology.

A nanomedicine approach enables co-delivery of cyclosporin A and gefitinib to potentiate the therapeutic efficacy in drug-resistant lung cancer

Drug resistance, accounting for therapeutic failure in the clinic, remains a major challenge to effectively manage cancer. Cyclosporin A (CsA) can reverse multidrug resistance (MDR), especially resistance to epidermal growth factor receptor tyrosine kinase inhibitors. However, the application of both drugs in cancer therapies is hampered by their poor aqueous solubility and low bioavailability due to oral administration. CsA augments the potency of gefitinib (Gef) in both Gef-sensitive and Gef-resistant cell lines. Here, we show that the simultaneous encapsulation of CsA and Gef within polyethylene glycol-block-poly(_{D, L}-lactic acid) (PEG-PLA) produced a stable and systemically injectable nanomedicine, which exhibited a sub-50-nm diameter and spherical structures. Impressively, the co-delivery of therapeutics via single nanoparticles (NPs) outperformed the oral administration of the free drug combination at suppressing tumor growth. Furthermore, in vivo results indicated that CsA formulated in NPs sensitized Gef-resistant cells and Gef-resistant tumors to Gef treatment by inactivating the STAT3/Bcl-2 signaling pathway. Collectively, our nanomedicine approach not only provides an alternative administration route for the drugs of choice but also effectively reverses MDR, facilitating the development of effective therapeutic modalities for cancer.

Injection of nanoparticles containing the anticancer drug gefitinib and the immunosuppressant cyclosporin A reverses drug-resistant cancer growth in mice. The development of multidrug resistance is the main reason why many forms of chemotherapy fail. Cyclosporin A, a drug used to prevent immune rejection after organ transplantation, has previously been shown to enhance the potency of gefitinib. Hangxiang Wang and colleagues at Zhejiang University, Hangzhou, China, have successfully combined cyclosporin A and gefitinib, two poorly water-soluble and slowly absorbed drugs, into stable injectable nanoparticles that delay the growth of gefitinib resistant human lung cancer cells as well as the growth of drug resistant tumors in mice. Importantly, this novel co-formulation was more effective than oral co-administration of the two drugs. Further investigation into this drug delivery route could yield much needed alternative treatments for patients with multidrug-resistant cancers.

Alterations of Gefitinib Pharmacokinetics by Co-administration of Herbal Medications in Rats

OBJECTIVE

To evaluate the potential pharmacokinetic interactions of the anticancer agent gefitinib (Iressa®) and the oriental medications Guipi Decoction (, GPD, Guibi-tang in Korean) and Bawu Decoction (, BWD, Palmul-tang in Korean).

METHODS

Methylcellulose (MC, control), GPD (1,200 mg/kg), or BWD (6,000 mg/kg) was orally administered to rats either as a single dose or multiple doses prior to gefitinib administration. To examine the effects of a single dose of the herbal medicines, gefitinib (10 mg/kg) was orally administered after 5 min or 1 h of MC or the herbal medicine pretreatments. To examine the effects of the multiple doses of the herbal medicines, gefitinib (10 mg/kg) was orally administered following 7 consecutive days of the administration of MC or each herbal medicine. The plasma concentrations of gefitinib were determined with liquid chromatography-tandem mass spectrometry assay. The plasma concentration-time profiles of gefitinib were analyzed with a noncompartmental analysis.

RESULTS

Gefitinib was rapidly absorbed and showed a monoexponential decline with an elimination half-life of 3.7-4.1 h. The pharmacokinetics of gefitinib was not affected by GPD pretreatment. However, a significantly lower maximum plasma concentration (C_max, P<0.05) and area under the curve (P<0.05), and a delayed time to reach C_max (T_max, P<0.01) were observed in both single- and multipledose BWD-pretreated rats compared with the control rats.

CONCLUSIONS

BWD and not GPD might delay and interfere with gefitinib absorption. Further evaluations of the clinical significance of these findings are needed.

In vitro and in vivo antitumor effect of gefitinib nanoparticles on human lung cancer

Gefitinib (GEF) is the first epidermal growth factor receptor (EGFR)-targeting agent launched as an anticancer drug. It is an accepted opinion that modifying GEF strong hydrophobicity and poor bioavailability would not only enhance its antitumor effects, but also reduce its side effects. In this study, GEF-loadedpoly(ε-caprolactone)-poly(ethyleneglycol)-poly(ε-caprolactone) (PCEC) -bearing nanoparticles (GEF-NPs) were prepared by a solid dispersion method and characterized. The particle sizes increased with the increase in GEF/PCEC mass ratio in feed. GEF-NPs (10%) were mono-dispersed, smaller than 24 nm, zeta potential was approximately -18 mV, percentage encapsulation and loading, were more than 9% and 92%, respectively, and drug was slowly released but without a biphasic pattern. Microscopy studies of the optimized formulation confirmed that the prepared nanoparticles are spherical in nature. Cytotoxicity results indicated that cell growth inhibition induced by free GEF and GEF-NPs were dose and time dependent. Compared with free GEF, GEF-NPs enhanced antitumor effects, reduced side effects and significantly prolonged survival time in vivo. CD31, ki-67 and EGFR expression were significantly lower in the GEF-NPs group compared with other groups (p< .05). These findings demonstrated that GEF-NPs have the potential to attain superior outcomes and to overcome complications such as organs toxicity, therapeutic resistance and disease relapse.

Role of gefitinib in the targeted treatment of non-small-cell lung cancer in Chinese patients

Non-small-cell lung cancer (NSCLC) is the most common type of lung cancer. Conventional treatment options have limited efficacy because most cases are in the advanced stage at the time of diagnosis. In recent years, gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, has shown its good antitumor activities in treating NSCLC in a number of studies. This paper reviews its role in the targeted treatment of NSCLC in Chinese patients.

Intestinal solubility and absorption of poorly water soluble compounds: predictions, challenges and solutions

We have explored for which type of compounds biorelevant dissolution profiling in simulated intestinal fluids would accurately predict solubility in human intestinal fluid. In total, 474 solubility values in simulated and aspirated human intestinal fluid for 78 drugs were compiled and analyzed. Significant solubilization in the colloidal structures was obtained in fasted and fed state fluids for drug compounds with a logD(oct)>3. Highly lipophilic compounds with high melting points (Tm > 200 °C) could also be significantly solubilized, but typically such compounds had solubility values in the lower µg/ml range also in the presence of the colloidal structures. On the basis of our analysis, compounds with a logD(oct)>3 should be explored in biorelevant dissolution media to better predict in vivo performance after oral dosing.

Chemical Analysis of Drug Biocrystals: A Role for Counterion Transport Pathways in Intracellular Drug Disposition

In mammals, highly lipophilic small molecule chemical agents can accumulate as inclusions within resident tissue macrophages. In this context, we characterized the biodistribution, chemical composition, and structure of crystal-like drug inclusions (CLDIs) formed by clofazimine (CFZ), a weakly basic lipophilic drug. With prolonged oral dosing, CFZ exhibited a significant partitioning with respect to serum and fat due to massive bioaccumulation and crystallization in the liver and spleen. The NMR, Raman, and powder X-ray diffraction (p-XRD) spectra of CLDIs isolated from the spleens of CFZ-treated mice matched the spectra of pure, CFZ hydrochloride crystals (CFZ-HCl). Elemental analysis revealed a 237-fold increase in chlorine content in CLDIs compared to untreated tissue samples and a 5-fold increase in chlorine content compared to CFZ-HCl, suggesting that the formation of CLDIs occurs through a chloride mediated crystallization mechanism. Single crystal analysis revealed that CFZ-HCl crystals had a densely packed orthorhombic lattice configuration. In vitro, CFZ-HCl formed at a pH of 4-5 only if chloride ions were present at sufficiently high concentrations (>50:1 Cl(-)/CFZ), indicating that intracellular chloride transport mechanisms play a key role in the formation of CLDIs. While microscopy and pharmacokinetic analyses clearly revealed crystallization and intracellular accumulation of the drug in vivo, the chemical and structural characterization of CLDIs implicates a concentrative, chloride transport mechanism, paralleling and thermodynamically stabilizing the massive bioaccumulation of a weakly basic drug.

Structural features of colloidal species in the human fasted upper small intestine

Objectives

This paper aims to study the features of colloidal species in the lumen of the upper small intestine of two healthy adults at fasted state by means of electron microscopy.

Methods

Samples were aspirated from a location near the ligament of Treitz 30 min (volunteer no. 1, Aspirate30min sample) and 60 min (volunteer no. 2, Aspirate60min sample), after administration of 240 ml of an aqueous solution in the fasted state.

Key findings

In the Aspirate30min sample micelles coexist with multi-, oligo- and unilamellar vesicles. Tubular structures and long structures were frequently visualised. In the Aspirate60min sample micelles, few unilamellar vesicles, long structures and tubular structures were the dominating structural features. In both samples, multivesicular structures and faceted vesicles (previously visualised at fed state) were absent. Structural features of both samples bear similarities with previously studied samples from the lower intestine in the fasted state. Micelles and unilamellar vesicles observed in both samples closely resemble morphological characteristics of those found in fluids simulating the colloidal species in fasted upper intestinal environment.

Conclusions

Features of colloidal species in contents of fasted small intestine have similarities with fluids simulating the contents in fasted upper small intestine and with contents of lower intestine in the fasted state.

Composition and physicochemical properties of fasted-state human duodenal and jejunal fluid: a critical evaluation of the available data

Various methods of sampling and analyzing intestinal fluids have been applied over the years. In this report, data that have been published to date about the composition of fasted-state human intestinal fluid (HIF) and its physicochemical properties are summarized and the influence of the methods used to generate the data is discussed. Key physiological parameters summarized include pH, buffer capacity, osmolarity, and ionic strength in both the fasted duodenum and jejunum. Furthermore, the bile salts and phospholipids in the fasted small intestine are addressed in terms of both qualitative and quantitative composition with respect to the different types and degrees of hydroxylation of bile salts. Taurocholate, glycocholate, and glycochenodeoxycholate were identified as the main bile salts. Lysolecithin was identified as the predominant phospholipid species in fasted HIF because of the enzymatic degradation of lecithin. Together with other intestinal surfactants, such as cholesterol and free fatty acids, the influence of bile acids and phospholipids on the surface tension of fasted HIF was evaluated. A good working knowledge of all the above-mentioned parameters is important to optimize the composition of biorelevant media, with a view to improving the prediction of in vivo dissolution and release performance of drugs and dosage forms.

Gefitinib

Gefitinib (Iressa®) is a selective inhibitor of epidermal growth factor, a growth factor that plays a pivotal role in the control of cell growth, apoptosis, and angiogenesis. Gefitinib is clinically used for the treatment of chemoresistant non-small cell lung cancer patients. Gefitinib is freely soluble in dimethylsulphoxide but slightly soluble in methanol and ethanol. Several methods of gefitinib synthesis are included in this review. UV spectroscopy of gefitinib showed a λmax of approximately 331nm, whereas IR spectroscopy principal peaks were observed at 3400cm(-1) (NH), 2956cm(-1) (CH2, CH, alkyl), 1625cm(-1) (CC, CN), 1500cm(-1) (HCCH, aryl), 1110cm(-1) (CO), 1028cm(-1) (CF). In addition, different analytical methods for determination of gefitinib are also described in this review. Pharmacokinetically, after oral administration, gefitinib is slowly absorbed with bioavailability of approximately 60% in human. Gefitinib is metabolized extensively in the liver into five metabolites by cytochrome P450s, primarily by CYP3A4 and to a lesser extent by CYP3A5 and CYP2D6. Gefitinib is eliminated mainly hepatically with total plasma clearance of 595mL/min after intravenous administration. Most of the adverse effects associated with gefitinib therapy are mild to moderate in severity and are usually reversible and manageable with appropriate intervention, such as diarrhea, dry skin, rash, nausea, and vomiting.

Review of the treatment of non-small cell lung cancer with gefitinib

In the past decade, molecular-targeted drugs have been focused upon for the treatment of cancer. In 2002, gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor became available in Japan for the treatment of non-small cell lung cancer (NSCLC). Over 80% of selected patients, such as EGFR mutation-positive patients, respond to gefitinib treatment; however, most patients develop acquired resistance to gefitinib within a few years. Recently, many studies have been performed to determine precisely how to select patients who will respond to gefitinib, the best timing for its administration, and how to avoid the development of acquired resistance as well as adverse drug effects. This article reviews the use of gefitinib for the treatment of NSCLC from a pharmaceutical viewpoint.

Drug absorption interactions between oral targeted anticancer agents and PPIs: is pH-dependent solubility the Achilles heel of targeted therapy?

A majority of the novel orally administered, molecularly targeted anticancer therapies are weak bases that exhibit pH-dependent solubility, and suppression of gastric acidity with acid-reducing agents could impair their absorption. In addition, a majority of cancer patients frequently take acid-reducing agents to alleviate symptoms of gastroesophageal reflux disease, thereby raising the potential for a common but underappreciated drug-drug interaction (DDI) that could decrease the exposure of anticancer medication and result in subsequent failure of therapy. This article is a review of the available clinical literature describing the extent of the interaction between 15 orally administered, small-molecule targeted anticancer therapies and acid-reducing agents. The currently available clinical data suggest that the magnitude of this DDI is largest for compounds whose in vitro solubility varies over the pH range 1-4. This range represents the normal physiological gastric acidity (pH ~1) and gastric acidity while on an acid-reducing agent (pH ~4).

Physicochemical properties of epidermal growth factor receptor inhibitors and development of a nanoliposomal formulation of gefitinib

Inhibitors of epidermal growth factor (EGF) receptor (EGFR) tyrosine kinases show efficacy in cancers that are highly addicted to nonmutated EGF signaling, but off-target effects limit therapy. Carrier-based formulations could reduce drug deposition in normal tissues, enhance tumor deposition, and reduce free drug concentrations, thereby reducing the side effects. Therefore, the feasibility of developing nanoliposomal formulations of EGFR inhibitors was investigated. Gefitinib and erlotinib fluorescence was characterized as a tool for formulation development. Peak excitation was 345 nm and peak emission was 385-465 nm, depending upon the environment polarity. Emission was negligible in water but intense in nonpolar solvents, membranes, or bound to serum proteins. Cellular uptake and distribution could also be imaged by fluorescence in drug-resistant tumor spheroids. Gefitinib fluorescence characteristics enabled facile optimization of formulations. Although 4-6 mol % gefitinib could be incorporated in the liposome bilayer, 40-60 mol % could be encapsulated in stable, remote-loaded liposomes consisting of distearoylphosphatidylcholine-polyethylene glycol-distereoylphosphatidylethanolamine-cholesterol (9:1:5 mol:mol:mol). Drug leakage in serum, monitored by fluorescence, was minimal over 24 h at 37°C. The results provide both promising lead formulations as well as novel tools for evaluating new formulations of structurally similar receptor tyrosine kinase inhibitors and their cellular uptake and tissue biodistribution.

Therapeutic drug monitoring in cancer chemotherapy

For a select number of drugs, proper management of patients includes monitoring serum or plasma concentrations of the drugs and adjusting the doses accordingly - this practice is referred to as therapeutic drug monitoring (TDM). The need for TDM arises when pharmacokinetic variability of drugs is not easily accounted for by common clinical parameters. Many chemotherapeutic drugs have large interindividual variability, yet TDM is not commonplace in chemotherapy management. This review will discuss pharmacokinetics in the context of chemotherapeutic drugs, examine the few instances where TDM is currently used in the field of oncology and propose other drugs where TDM might be useful for dose adjustments in the management of chemotherapy.

Metabolism considerations for kinase inhibitors in cancer treatment

IMPORTANCE OF THE FIELD

A concerted effort by the pharmaceutical industry over the last decade has led to the successful clinical development of protein kinase inhibitors as effective targeted therapies for certain cancers.

AREAS COVERED IN THIS REVIEW

This review details eight small molecule kinase inhibitors that have been approved for the treatment of cancer in either the US or Europe as of March 2010: imatinib, sorafenib, gefitinib, erlotinib, dasatinib, lapatinib, sunitinib and nilotinib. These eight compounds vary from the relatively specific inhibitor lapatinib to the more promiscuous kinase inhibitors dasatinib and sunitinib.

WHAT THE READER WILL GAIN

A brief discussion on the biology of each inhibitor, selectivity over other kinases and toxicity is provided. A more detailed discussion on the metabolism, drug transporters, drug-drug interactions and possible roles of metabolism in compound toxicity is provided for each compound.

TAKE HOME MESSAGE

The majority of the currently approved kinase inhibitors is heavily influenced by drug transporters and significantly affected by CYP3A4 inhibitors/inducers. At least three, gefitinib, erlotinib and dasatinib, are metabolized to form reactive metabolites capable of covalently-binding biomolecules.

Comparison of the drug-drug interactions potential of erlotinib and gefitinib via inhibition of UDP-glucuronosyltransferases

We aimed to investigate and compare the effects of erlotinib and gefitinib on UDP-glucuronosyltransferase (UGT) activities and to quantitatively evaluate their drug-drug interaction (DDI) potential due to UGT inhibition. The inhibitory effects of erlotinib and gefitinib on UGTs were determined using high-performance liquid chromatography by measuring the formation rates for 4-methylumbelliferone (4-MU) glucuronide, imipramine N-glucuronide, and bilirubin glucuronides using recombinant human UGT isoforms and human liver microsomes (HLMs) in the absence or presence of erlotinib and gefitinib. Inhibition kinetic studies were conducted. Area under the curve (AUC) ratios were used to predict the risk of potential DDI in vivo. Erlotinib exhibited selective potent competitive inhibition against 4-MU glucuronidation by UGT1A1, and gefitinib demonstrated a wide range of inhibition against UGT-mediated 4-MU glucuronidation, particularly against UGT1A1, UGT1A7, UGT1A9, and UGT2B7. Erlotinib also exerted potent mixed inhibition against bilirubin glucuronidation in HLMs. We estimated that coadministration of erlotinib at 100 mg/day or higher doses may result in at least a 30% increase in the AUC of drugs predominantly cleared by UGT1A1. Thus, the coadministration of erlotinib with drugs primarily cleared by UGT1A1 may result in potential DDI. In contrast, gefitinib is unlikely to cause a clinically significant DDI through inhibition of glucuronidation.

Gefitinib-cyclodextrin inclusion complexes: physico-chemical characterization and dissolution studies

BACKGROUND

Gefitinib, an anticancer drug, has an extremely low aqueous solubility, and its oral absorption is limited by its dissolution rate. The solubility and dissolution of gefitinib can be improved by complexation with cyclodextrins (CDs).

METHODS

Phase solubility studies of gefitinib with hydroxypropyl betaCD (HPbetaCD) and randomly methylated betaCD (RMbetaCD) in n various aqueous systems was conducted to characterize the complexes in the liquid state. The inclusion complexes in the solid state were prepared by freeze-drying method and characterized by X-ray diffractometry (X-RD) and differential scanning calorimetry (DSC).

RESULTS

Gefitinib formed stable complexes with HPbetaCD and RMbetaCD in distilled water as indicated by the association rate constants (Ks) of 458.9 and 1096.2 M(-1) for HPbetaCD and RMbetaCD, respectively. The complexation of gefitinib with CDs in pH 4.5 acetate buffer indicated an A(N) type of phase-solubility diagrams, whereas gefitinib and HPbetaCD in distilled water in the presence of polymers such as polyvinyl pyrrolidone K-30 (PVP) or hydroxypropyl methylcellulose E3 (HPMC) resulted in A(P)-type phase-solubility diagrams. The solid-state amorphous complexes (as described by DSC and X-RD) showed substantial increases in the solubility and dissolution rate of gefitinib with both CDs. Further increases in the solubility and dissolution rate of the gefitinib-HPbetaCD freeze-dried complex were obtained by physically mixing the complex with PVP and HPMC.

CONCLUSION

Gefitinib formed stable inclusion complexes with HPbetaCD and RMbetaCD, and the solubility and dissolution rate of the drug was significantly increased.

Design and development of polymer conjugates as anti-angiogenic agents

Angiogenesis, the formation of new blood vessels from pre-existing vasculature, is one of the central key steps in tumor progression and metastasis. Consequently, it became an important target in cancer therapy, making novel angiogenesis inhibitors a new modality of anticancer agents. Although relative to conventional chemotherapy, anti-angiogenic agents display a safer toxicity profile, the vast majority of these agents are low-molecular-weight compounds exhibiting poor pharmacokinetic profile with short half-life in the bloodstream and high overall clearance rate. The "Polymer Therapeutics" field has significantly improved the therapeutic potential of low-molecular-weight drugs and proteins for cancer treatment. Drugs can be conjugated to polymeric carriers that can be either directly conjugated to targeting proteins or peptides or derivatized with adapters conjugated to a targeting moiety. This approach holds a significant promise for the development of new targeted anti-angiogenic therapies as well as for the optimization of existing anti-angiogenic drugs or polypeptides. Here we overview the innovative approach of targeting tumor angiogenesis using polymer therapeutics.

Protein kinase inhibitors of the quinazoline class exert anti-cytomegaloviral activity in vitro and in vivo

Cytomegalovirus infection is associated with severe disease in immunocompromised individuals. Current antiviral therapy faces several limitations. In a search of novel drug candidates, we describe here the anti-cytomegaloviral properties of two compounds of the chemical class of quinazolines, gefitinib (Iressa) and Ax7396 (RGB-315389). Both compounds showed strong inhibitory effects in vitro against human and animal cytomegaloviruses with IC(50)s in a low micromolar range. Cytotoxicity did not occur at these effective concentrations. The antiviral mode of action was based on the inhibition of protein kinase activity, mainly directed to a viral target kinase (UL97/M97) in addition to cellular target candidates. This was demonstrated by a high sensitivity of the respective protein kinases in vitro and by infection experiments with viral mutants carrying genomic alterations in the ORF UL97/M97 modulating viral drug sensitivity. In a guinea pig model, gefitinib showed inhibition of cytomegaloviral loads in blood and lung tissue. Importantly, the rate of mortality of infected animals was reduced by gefitinib treatment. In contrast to the in vitro data, Ax7396 showed no significant antiviral activity in a mouse model. Further in vivo analyses have to assess the potential use of gefitinib in the treatment of cytomegalovirus disease.

Intestinal permeability and its relevance for absorption and elimination

Human jejunal permeability (P(eff)) is determined in the intestinal region with the highest expression of carrier proteins and largest surface area. Intestinal P(eff) are often based on multiple parallel transport processes. Site-specific jejunal P(eff) cannot reflect the permeability along the intestinal tract, but they are useful for approximating the fraction oral dose absorbed. It seems like drugs with a jejunal P(eff) > 1.5 x 10(-4) cm s(-1) will be completely absorbed no matter which transport mechanism(s) are utilized. Many drugs that are significantly effluxed in vitro have a rapid and complete intestinal absorption (i.e. >85%) mediated by passive transcellular diffusion. The determined jejunal P(eff) for drugs transported mainly by absorptive carriers (such as peptide and amino acid transporters) will accurately predict the fraction of the dose absorbed as a consequence of the regional expression. The data also show that: (1) the human intestinal epithelium has a large resistance towards large and hydrophilic compounds; and (2) the paracellular route has a low contribution for compounds larger than approximately molecular weight 200. There is a need for more exploratory in vivo studies to clarify drug absorption and first-pass extraction along the intestine. One is encouraged to develop in vivo perfusion techniques for more distal parts of the gastrointestinal tract in humans. This would stimulate the development of more relevant and complex in vitro absorption models and form the basis for an accurate physiologically based pharmacokinetic modelling of oral drug absorption.