Validation of bioanalytical chromatographic methods

A strategy is discussed for the validation of chromatographic methods that are developed to quantify drugs in biological matrices. Both the validation terminology and the hypothesis testing are briefly reviewed. The emphasis is on the design of the experiments required to allow a reliable conclusion about acceptance or rejection of the bioanalytical method. In particular, it is explained how to evaluate the calibration line, devise experiments to estimate precision and bias and how to determine the stability of the analyte between the time of the sample collection and the analysis of the processed sample.     

Matrix metalloproteinase inhibitors: a review on bioanalytical methods, pharmacokinetics and metabolism

Enzymes are major drug targets in drug discovery and development processes in the pharmaceutical and biotechnology industry. A recent survey found that nearly half of all the marketed small-molecule drugs are inhibitors of enzymes. Matrix metalloproteinases (MMPs) are a family of 28 enzymes capable of degrading the constituents of the extracellular matrix (ECM) and the basement-membrane. MMPs play an essential role in several normal physiological processes including growth, wound healing and tissue repair. Over-expression and activation of MMPs has been linked to a range of diseases which include osteoarthritis, tumor metastasis, angiogenesis and cardiovascular diseases. The development of MMP inhibitors as therapeutic agents has kept an important place in drug discovery. Therefore, there is also an increasing need for robust analytical methods for evaluation of inhibitory potency and for the analysis of MMP inhibitors and their metabolites which can even play a more significant role than the parent drug. Modern analytical techniques and hyphenated instrumentations such as liquid chromatography-mass spectrometry with a function of structure elucidation can provide a profound insight into the research of MMP inhibitors and also serve as a complementary method to zymographic techniques for the analysis of biological samples. This review mainly summarizes bioanalytical methods, pharmacokinetics and related metabolites of MMP inhibitors over the last 12 years.     

An analysis of the SFSTP guide on validation of chromatographic bioanalytical methods: progress and limitations

The Société Fran?aise des Sciences et Techniques Pharmaceutiques (SFSTP) published in 1997 a guide on the validation of chromatographic bio-analytical methods, which introduces new concepts in three different areas: stages of the validation, test of acceptability of a method and design of experiments to perform. In 'stages of validation', the SFSTP guide requires two phases to validate a method. The first phase, called 'prevalidation', is intended to (1) identify the model to use for the calibration curve; (2) evaluate the limits of quantitation; and (3) provide good estimates of the precision and bias of the method before designing the 'validation' phase per se. In the 'test of acceptability', the use of the interval hypotheses is envisaged by the SFSTP guide, not on the parameters of bias and precision, but on individual results by mixing mean bias and intermediate precision in a single test. The SFSTP guide also avoids the use of Satterthwaite's df for testing the acceptability. The reasons for those choices are discussed extensively. In 'design of experiments', much effort has been devoted to improving the quality of results by optimally designing and sizing the experiments to perform in validation. The rationale for using near D-optimal designs for the calibration curve is demonstrated and sample sizes are proposed to correctly size the validation experiments.     

Development and validation of a high-performance liquid chromatographic method for bioanalytical application with rimonabant

A simple and feasible high-performance liquid chromatographic method with UV detection was developed and validated for the quantification of rimonabant in human plasma. The chromatographic separation was carried out in a Hypersil BDS, C₁₈ column (250 mm × 4.6 mm; 5 μm). The mobile phase was a mixture of 10 mM phosphate buffer and acetonitrile (30:70, v/v) at a flow rate of 1.0 ml/min. The UV detection was set at 220 nm. The extraction recovery of rimonabant in plasma at three quality control (QC) samples was ranged from 84.17% to 92.64%. The calibration curve was linear for the concentration range of 20–400 ng/ml with the correlation coefficient (r²) above 0.9921. The method was specific and sensitive with the limit of quantification of 20 ng/ml. The accuracy and precision values obtained from six different sets of QC samples analyzed in separate occasions ranged from 88.13% to 106.48% and 0.13% to 3.61%, respectively. In stability tests, rimonabant in human plasma was stable during storage and assay procedure. The method is very simple, sensitive and economical and the assay was applied to human plasma samples in a clinical (pharmacokinetic) study of rimonabant.     

Social media and pharmacovigilance: A review of the opportunities and challenges

Adverse drug reactions come at a considerable cost on society. Social media are a potentially invaluable reservoir of information for pharmacovigilance, yet their true value remains to be fully understood. In order to realize the benefits social media holds, a number of technical, regulatory and ethical challenges remain to be addressed. We outline these key challenges identifying relevant current research and present possible solutions.     

Osteoporosis: challenges and new opportunities for therapy

Osteoporosis is a chronic disease that affects a large number of both men and women and is characterized by a decrease in bone mass, as well as weakened bones. It causes a significant amount of morbidity and mortality in patients and is often only diagnosed after a fracture occurs. This review will highlight recent advances in the development of novel anabolic approaches for treatment of osteoporosis, such as parathyroid hormone (PTH), calcium sensing receptor modulators, statins and prostanoid receptor agonists. Selected antiresorptive targets (cathepsin K inhibitors and vitronectin receptor antagonists) will also be surveyed.     

Rotavirus vaccines: opportunities and challenges

Each year rotavirus gastroenteritis episodes in young children cause more than 500,000 deaths and 2.4 million hospital admissions worldwide. Vaccine development became a priority when improved personal hygiene and living standards failed to significantly reduce this disease burden. Rotavirus vaccines were developed mimicking natural immunity by protecting against severe gastroenteritis in young children, which would otherwise lead to health-care attendance, hospitalization or even death. Licensed rotavirus vaccines appear safe and are well-tolerated. In high and middle-income countries they provide 80-100% protection against severe disease and 70-80% protection against rotavirus gastroenteritis of any severity, depending upon the population studied. However, rotavirus vaccines remain to be fully evaluated in low-income countries where reduced immunogenicity of oral vaccines, greater strain diversity and difficulties reaching target populations might decrease immunization program performance. Nevertheless, if these challenges are met, rotavirus vaccines should help reduce the 5% of all childhood deaths attributable to rotavirus gastroenteritis.     

Dengue vaccine: opportunities and challenges

Despite many successes in the field of vaccinology over the past century, several important scourges for which effective vaccines remain elusive continue to be threats to public health. The mosquito-borne dengue virus causes millions of infections in tropical and subtropical regions throughout the world, and is responsible for an annual mortality that measures in the thousands. The ubiquitous presence of dengue virus, and its potentially lethal complications, have made the development of an effective vaccine against the virus a priority. However, before such a vaccine can be created, the basic immunology surrounding dengue infection must be clarified. Such research is underway, including efforts focusing on the response of T-cells and the potentially central role of this response in dengue pathophysiology. 'Shaping' the T-cell response may be the key to successful dengue vaccine design.     

Development of green bioanalytical hplc method for estimation of irbesartan in rat plasma: Towards greener chromatographic science

Environmental friendly, less toxic and reliable liquid chromatography method for estimation of irbesartan was developed and validated in rat plasma. The chromatographic separation was performed on Hypersil Gold C18 column (4.6 mm × 250 mm, 5 µm), using a mobile phase of 0.5% ortho-phosphoric acid (pH 3.0) and ethanol (65:35 v/v) under isocratic elution with a flow rate of 0.8 mL/min. The column eluent was monitored at 225 nm using PDA detector. The retention time of irbesartan was found to be 4.8 min with excellent peak symmetry. Linearity of the developed method was observed for the drug concentration ranging between 0.2 and 10 μg/mL. Other parameters such as accuracy, precision and recovery were found to be well within the acceptable limits. The method was successfully applied for the estimation of irbesartan in rat plasma and various pharmacokinetic parameters were computed. The proposed method was found to be greener and cost effective than the reported methods in literature, hence, can be used for routine analysis of drug in biological matrix without affecting the environment.     

Antioxidants for prostate cancer chemoprevention: challenges and opportunities

Extensive research has led to the firm conclusion that antioxidants protect cells from damage caused by oxidative stress and its associated pathological conditions including inflammation. It has also been established that inflammation is a precursor in neoplastic transformation of the prostate. Although, a vast body of experimental and clinical evidence shows efficacy of antioxidants as preventive strategies for prostate cancer, there is a lack of consistent agreement in outcomes especially from recent large-scale randomized clinical trials. Despite these concerns, our understanding of the preventive mechanisms as well as clinical efficacy and safety data indicate that novel antioxidant therapeutics still hold great promise for prostate cancer chemoprevention. We propose that for effective use of antioxidants for prostate cancer prevention, further high impact translational research is needed with special attention on selecting those patients who will benefit from such intervention. Therefore, it is important to validate predictive biomarkers from successful trials and combine this with knowledge of preclinical characterization of antioxidants (and combinations) that will eventually facilitate the development of 'personalized prostate cancer chemoprevention'. In this review, we briefly describe some common and emerging antioxidants that have shown benefits in preclinical and clinical settings. Above all, we focus on summarizing the progress we made thus far in prostate cancer chemoprevention using antioxidants, the heightened interest and challenges in the future.     

Guideline on bioanalytical method validation

在创新药物研发过程中,生物基质（如血清、血浆、血液、尿液、唾液）中的药物浓度测定是一个重要的方面。其数据可用于支持新活性物质的应用和仿制药及已授权药品的变更申请。动物的毒代动力学研究和临床试验,包括生物等效性研究的结果为原料药或产品的安全性和有效性提供关键性的数据支持。因此,应用经过充分验证并记录到一个满意标准的生物分析方法以得到可靠的结果,这是非常重要的。2012年2月1日,欧洲药品管理局（EMA）开始实施最新的《生物样品分析方法验证指南》（Guideline on bioanalytical method validation）,本指南适用于动物的毒代动力学研究和所有阶段的临床试验中获得的生物样品中的药物浓度的生物分析方法的验证。本文摘录其方法学验证部分,抛砖引玉,供相关研究人员参考。     

Management of retinoblastoma: opportunities and challenges

Nano-delivery systems have significantly evolved over the last decade for the treatment of cancer by enabling site-specific delivery and improved bioavailability. The widely investigated nanoparticle systems are biodegradable polyesters, dendrimers, liposomes, mesoporous silica and gold nanoparticles. These particles when conjugated with different targeting motifs enhance the therapeutic efficiency of the drug molecules and biocompatibility. However, the application of such systems towards the treatment of retinoblastoma (RB), a rapidly spreading childhood eye cancer, still remains in its infancy. Nanoparticle-based systems that have been investigated for RB therapy have displayed improved drug delivery to the most restricted posterior segment of the eyes and have increased intra-vitreal half-life of the chemotherapy agents highlighting its potential in treatment of this form of cancer. This review focuses on the challenges involved in the treatment of RB and highlights the attempts made to develop nano-dimensional systems for the treatment of RB.