Effect of lapatinib on oral digoxin absorption in patients

Lapatinib: A comprehensive profile

Lapatinib is an anticancer used for treatment of the patients with advanced metastatic breast cancer in conjunction with the chemotherapy drug capecitabine or with letrozole for the treatment of postmenopausal women with hormone receptor-positive metastatic breast cancer. This comprehensive profile of Lapatinib gives more detailed information about the description, formulae, Elemental Analysis, Uses and application. Furthermore, methods and schemes are outlined for the preparation of the drug substance. The physical properties of the medication include constant of ionization, solubility, X-ray powder diffraction pattern, differential scanning calorimetry, thermal conduct and spectroscopic studies are investigated. The methods employed in bulk medicines and/or in pharmaceutical formulations to analyze the drug substance include spectrophotometric, electrochemical and the chromatographic methods are indicated. Other studies on this drug substance include drug stability, pharmaceutical applications, mechanism of action, pharmacodynamics, and a dosing information are also reviewed.

Quantitative prediction of pharmacokinetic properties of drugs in humans: Recent advance in in vitro models to predict the impact of efflux transporters in the small intestine and blood-brain barrier

Efflux transport systems are essential to suppress the absorption of xenobiotics from the intestinal lumen and protect the critical tissues at the blood-tissue barriers, such as the blood-brain barrier. The function of drug efflux transport is dominated by various transporters. Accumulated clinical evidences have revealed that genetic variations of the transporters, together with coadministered drugs, affect the expression and/or function of transporters and subsequently the pharmacokinetics of substrate drugs. Thus, in the preclinical stage of drug development, quantitative prediction of the impact of efflux transporters as well as that of uptake transporters and metabolic enzymes on the pharmacokinetics of drugs in humans has been performed using various in vitro experimental tools. Various kinds of human-derived cell systems can be applied to the precise prediction of drug transport in humans. Mathematical modeling consisting of each intrinsic metabolic or transport process enables us to understand the disposition of drugs both at the organ level and at the level of the whole body by integrating a variety of experimental results into model parameters. This review focuses on the role of efflux transporters in the intestinal absorption and brain distribution of drugs, in addition to recent advances in predictive tools and methodologies.

Clinical significance of P-class pumps in cancer

P-class pumps are specific ion transporters involved in maintaining intracellular/extracellular ion homeostasis, gene transcription, and cell proliferation and migration in all eukaryotic cells. The present review aimed to evaluate the role of P-type pumps [Na⁺/K⁺ ATPase (NKA), H⁺/K⁺ ATPase (HKA) and Ca2⁺-ATPase] in cancer cells across three fronts, namely structure, function and genetic expression. It has been shown that administration of specific P-class pumps inhibitors can have different effects by: i) Altering pump function; ii) inhibiting cell proliferation; iii) inducing apoptosis; iv) modifying metabolic pathways; and v) induce sensitivity to chemotherapy and lead to antitumor effects. For example, the NKA β2 subunit can be downregulated by gemcitabine, resulting in increased apoptosis of cancer cells. The sarcoendoplasmic reticulum calcium ATPase can be inhibited by thapsigargin resulting in decreased prostate tumor volume, whereas the HKA α subunit can be affected by proton pump inhibitors in gastric cancer cell lines, inducing apoptosis. In conclusion, the present review highlighted the central role of P-class pumps and their possible use and role as anticancer cellular targets for novel therapeutic chemical agents.

Pleiotropic Roles of ABC Transporters in Breast Cancer

Chemotherapeutics are the mainstay treatment for metastatic breast cancers. However, the chemotherapeutic failure caused by multidrug resistance (MDR) remains a pivotal obstacle to effective chemotherapies of breast cancer. Although in vitro evidence suggests that the overexpression of ATP-Binding Cassette (ABC) transporters confers resistance to cytotoxic and molecularly targeted chemotherapies by reducing the intracellular accumulation of active moieties, the clinical trials that target ABCB1 to reverse drug resistance have been disappointing. Nevertheless, studies indicate that ABC transporters may contribute to breast cancer development and metastasis independent of their efflux function. A broader and more clarified understanding of the functions and roles of ABC transporters in breast cancer biology will potentially contribute to stratifying patients for precision regimens and promote the development of novel therapies. Herein, we summarise the current knowledge relating to the mechanisms, functions and regulations of ABC transporters, with a focus on the roles of ABC transporters in breast cancer chemoresistance, progression and metastasis.

Interaction between phytotherapy and oral anticancer agents: prospective study and literature review

Cancer is becoming more prevalent in elderly patient. Due to polypharmacy, older adults with cancer are predisposed to drug-drug interactions. There is also an increasing interest in the use of complementary and alternative medicine (CAM). Thirty to seventy percent of patients with cancer have used CAM. Through pharmaceutical counseling sessions, we can provide advices on herb-drug interactions (HDI). All the patients seen in pharmaceutical counseling sessions were prospectively included. Information was collected during these sessions: prescribed medication (oral anticancer agents (OAA) and other drugs), CAM (phytotherapy especially), and use of over-the-counter (OTC) drugs. If pharmacist considered an interaction or an intervention clinically relevant, the oncologist was notified. Then, a literature review was realized to identify the potential HDI (no interactions, precautions for use, contraindication). Among 201 pharmacist counseling sessions, it resulted in 104 interventions related to 46 HDI, 28 drug-drug interactions and 30 others (wrong dosage, omission…). To determine HDI, we review 73 medicinal plants which are used by our patients with cancer and 31 OAA. A total of 1829 recommendations were formulated about 59 (75%) medical plants and their interaction with an OAA. Herb-drug interactions should not be ignored by healthcare providers in their management of cancer patients in daily practice.

ABCG2/BCRP: variants, transporter interaction profile of substrates and inhibitors

INTRODUCTION

ABCG2 has a broad substrate specificity and is one of the most important efflux proteins modulating pharmacokinetics of drugs, nutrients and toxicokinetics of toxicants. ABCG2 is an important player in transporter-mediated drug-drug interactions (tDDI). Areas covered: The aims of the review are i) to cover transporter interaction profile of substrates and inhibitors that can be utilized to test interaction of drug candidates with ABCG2, ii) to highlight main characteristics of in vitro testing and iii) to describe the structural basis of the broad substrate specificity of the protein. Preclinical data utilizing Abcg2/Bcrp1 knockouts and clinical studies showing effect of ABCG2 c.421C>A polymorphism on pharmacokinetics of drugs have provided evidence for a broad array of drug substrates and support drug - ABCG2 interaction testing. A consensus on using rosuvastatin and sulfasalazine as intestinal substrates for clinical studies is in the formation. Other substrates relevant to the therapeutic area can be considered. Monolayer efflux assays and vesicular transport assays have been extensively utilized in vitro. Expert opinion: Clinical substrates display complex pharmacokinetics due to broad interaction profiles with multiple transporters and metabolic enzymes. Substrate-dependent inhibition has been observed for several inhibitors. Harmonization of in vitro and in vivo testing makes sense. However, rosuvastatin and sulfasalazine are not efficiently transported in either MDCKII or LLC-PK1-based monolayers. Caco-2 monolayer assays and vesicular transport assays are potential alternatives.

Clinically relevant drug interactions with multikinase inhibitors: a review

Multikinase inhibitors (MKIs), including the tyrosine kinase inhibitors (TKIs), have rapidly become an established factor in daily (hemato)-oncology practice. Although the oral route of administration offers improved flexibility and convenience for the patient, challenges arise in the use of MKIs. As MKIs are prescribed extensively, patients are at increased risk for (severe) drug–drug interactions (DDIs). As a result of these DDIs, plasma pharmacokinetics of MKIs may vary significantly, thereby leading to high interpatient variability and subsequent risk for increased toxicity or a diminished therapeutic outcome. Most clinically relevant DDIs with MKIs concern altered absorption and metabolism. The absorption of MKIs may be decreased by concomitant use of gastric acid-suppressive agents (e.g. proton pump inhibitors) as many kinase inhibitors show pH-dependent solubility. In addition, DDIs concerning drug (uptake and efflux) transporters may be of significant clinical relevance during MKI therapy. Furthermore, since many MKIs are substrates for cytochrome P450 isoenzymes (CYPs), induction or inhibition with strong CYP inhibitors or inducers may lead to significant alterations in MKI exposure. In conclusion, DDIs are of major concern during MKI therapy and need to be monitored closely in clinical practice. Based on the current knowledge and available literature, practical recommendations for management of these DDIs in clinical practice are presented in this review.

Evaluation of transporters in drug development: Current status and contemporary issues

Transporters govern the access of molecules to cells or their exit from cells, thereby controlling the overall distribution of drugs to their intracellular site of action. Clinically relevant drug-drug interactions mediated by transporters are of increasing interest in drug development. Drug transporters, acting alone or in concert with drug metabolizing enzymes, can play an important role in modulating drug absorption, distribution, metabolism and excretion, thus affecting the pharmacokinetics and/or pharmacodynamics of a drug. The drug interaction guidance documents from regulatory agencies include various decision criteria that may be used to predict the need for in vivo assessment of transporter-mediated drug-drug interactions. Regulatory science research continues to assess the prediction performances of various criteria as well as to examine the strength and limitations of each prediction criterion to foster discussions related to harmonized decision criteria that may be used to facilitate global drug development. This review discusses the role of transporters in drug development with a focus on methodologies in assessing transporter-mediated drug-drug interactions, challenges in both in vitro and in vivo assessments of transporters, and emerging transporter research areas including biomarkers, assessment of tissue concentrations, and effect of diseases on transporters.