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At least 19 recordsLinked to original sources

Drug discovery, drug development and the emerging world of pharmacogenomics: prospecting for information in a data-rich landscape.

Drug development is a very expensive and inefficient process. Currently, it takes on average 15 years and costs approximately US $500 million to bring a new drug to market, with the pharmaceutical industry spending more than US $20 billion in identifying and developing drugs in 1998. Twenty-two percent of this total was spent on screening assays and toxicity testing. Yet the rapidly accelerating advances in high-throughput technologies, including screening and robotics, combinatorial chemistry, and genomics makes this an extremely data-rich environment. Add to that the new paradigms of pharmacogenomics and 'customized medicine', and the question is, are we helping or hurting our cause? Clearly, interpreting this flood of data and turning it into useful information is our next great hurdle. By extending the pharmacogenomic paradigm to the drug discovery process, this paper intends to put the scope of the problem into context.

Animals↗

Caenorhabditis elegans: a versatile platform for drug discovery.

Drug discovery and drug target identification are two intimately linked facets of intervention strategies aimed at effectively combating pathological conditions in humans. Simple model organisms provide attractive platforms for devising and streamlining efficient drug discovery and drug target identification methodologies. The nematode worm Caenorhabditis elegans has emerged as a particularly convenient and versatile tool that can be exploited to achieve these goals. Although C. elegans is a relatively modern addition to the arsenal of model organisms, its biology has already been investigated to an exceptional level. This, coupled with effortless handling and a notable low cost of cultivation and maintenance, allows seamless implementation of high-throughput drug screening approaches as well as in-depth genetic and biochemical studies of the molecular pathways targeted by specific drugs. In this review, we introduce C. elegans as a model organism with significant advantages toward the identification of molecular drug targets. In addition, we discuss the value of the worm in the development of drug screening and drug evaluation protocols. The unique features of C. elegans, which greatly facilitate drug studies, hold promise for both deciphering disease pathogenesis and formulating educated and effective therapeutic interventions.

Animals↗

Optimizing the use of open-source software applications in drug discovery.

Drug discovery is a time consuming and costly process. Recently, a trend towards the use of in silico computational chemistry and molecular modeling for computer-aided drug design has gained significant momentum. This review investigates the application of free and/or open-source software in the drug discovery process. Among the reviewed software programs are applications programmed in JAVA, Perl and Python, as well as resources including software libraries. These programs might be useful for cheminformatics approaches to drug discovery, including QSAR studies, energy minimization and docking studies in drug design endeavors. Furthermore, this review explores options for integrating available computer modeling open-source software applications in drug discovery programs.

Computer-Aided Design↗

Carbohydrates as scaffolds in drug discovery.

Drug discovery has long suffered from the difficulty of having to place pharmacophoric groups in just the right spatial arrangement to elicit the desired biological response. Although some molecule classes have been discovered that seem to be privileged structures for at least some drug-receptor interactions, there remains the challenge to design and synthesize molecules with high specific affinity to pharmacologically important targets. With their high density of stereochemical information and their relative rigidity, carbohydrates provide excellent platforms upon which to display a number of substituents in a sterically defined way, hence offering the opportunity to harness their unique features for the drug-discovery process. This review highlights the progress that has been made in the development of carbohydrate scaffolds for drug discovery.

Carbohydrate Conformation↗

In vitro high throughput screening of compounds for favorable metabolic properties in drug discovery.

Drug metabolism can have profound effects on the pharmacological and toxicological profile of therapeutic agents. In the pharmaceutical industry, many in vitro techniques are in place or under development to screen and optimize compounds for favorable metabolic properties in the drug discovery phase. These in vitro technologies are meant to address important issues such as: (1) is the compound a potent inhibitor of drug metabolising enzymes (DMEs)? (2) does the compound induce the expression of DMEs? (3) how labile is the compound to metabolic degradation? (4) which specific enzyme(s) is responsible for the compound's biotransformation? and (5) to which metabolites is the compound metabolized? Answers to these questions provide a basis for judging whether a compound is likely to have acceptable pharmacokinetic properties in vivo. To address these issues on the increasing number of compounds inundating the drug discovery programs, high throughput assays are essential. A combination of biochemical advances in the understanding of the function and regulation of DMEs (in particular, cytochromes P450, CYPs) and automated analytical technologies are revolutionizing drug metabolism research. Automated LC-MS based metabolic stability, fluorescence, radiometric and LC-MS based CYP inhibition assays are now in routine use. Automatible models for studying CYP induction based on enzyme activity, quantitative RT-PCR and reporter gene systems are being developed. We will review the utility and limitations of these HTS approaches and highlight on-going developments and emerging technologies to answer metabolism questions at the different stages of the drug discovery process.

Animals↗

High throughput screening in drug discovery.

Drug discovery is a highly complex and multidisciplinary process which goal is to identify new antitumoral drugs. The screening attrition rate in the current drug discovery protocols suggests that one marketable drug emerges from approximately one million screened compounds. This leads to pressure to screen larger libraries in order to continue the pipeline and to the development of High Throughput Screening. HTS is only a name for specific developments in laboratory automation to collect a large amount of experimental data in a relatively short time. HTS can test hundreds of thousands of compounds per day, however, if fewer compounds could be tested without compromising the probability of success, the cost and time would be greatly reduced. To that end, new developments in large-scale cell biology and compound library design in silico have evolved to obtain data with higher predictability of clinical efficacy.

Animals↗

Transporters and drug discovery: why, when, and how.

Drug transporters are now increasingly recognized as important determinants of variable drug disposition and response. In addition, transporter associated problems appear to be occurring with greater frequency during the drug discovery and development process. What has not been clear is whether drug transporter related issues are a truly new problem, or whether such issues had existed all along, but were previously unrecognized or ignored. In this review, a brief overview of key drug transporters will be outlined. In addition, a commentary on specific issues of relevance to pharmaceutical sciences in terms of the role and relevance of drug transporters to the drug discovery and development process is provided.

Animals↗

Proteomics in drug discovery.

Drug discovery is a prolonged process that uses a variety of tools from diverse fields. To accelerate the process, a number of biotechnologies, including genomics, proteomics and a number of cellular and organismic methodologies, have been developed. Proteomics development faces interdisciplinary challenges, including both the traditional (biology and chemistry) and the emerging (high-throughput automation and bioinformatics). Emergent technologies include two-dimensional gel electrophoresis, mass spectrometry, protein arrays, isotope-encoding, two-hybrid systems, information technology and activity-based assays. These technologies, as part of the arsenal of proteomics techniques, are advancing the utility of proteomics in the drug-discovery process.

Animals↗

In vivo pharmacokinetic screening in cassette dosing experiments; the use of on-line Pprospekt liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry technology in drug discovery.

Drug discovery is a fast growing field and the number of compounds generated daily by the pharmecutical industry is enormous. The necessity of developing new experimental strategies and analytical methods to rapidly screen the pharmacokinetics (PK) behavior of these compounds becomes a real challenge. A novel strategy to support in vivo PK screening in cassette doing experiments, using a fully automated system capable of analyzing between 320 to 960 samples a day by instrument in n-in-one experiment ( n = 64 in this work), has been developed. Using an on-line extraction technique, the average observed recovery was 64% using a single C18 procedure. A weighted (1/x) linear equation was used to perform standard calibration (0.5 to 500 ng/microL) and the average R value obtained was 0.994 (R2 = 0.997) for 63 analytes. The limit of detection, defined as a signal-to-noise ratio of 3 or greater, was found to be 25 pg for 41 of the 63 analytes (65%) and 250 pg for 57 of the 63 analytes (90%). The complete automation procedure using the Prospekt-LC-APCI/MS/MS system has substantially improved throughput in the area of drug discovery and bioanalysis.

Calibration↗

Designer drugs: the evolving science of drug discovery.

Drug discovery and design are fundamental to drug development. Until recently, most drugs were discovered through random screening or developed through molecular modification. New technologies are revolutionizing this phase of drug development. Rational drug design, using powerful computers and computational chemistry and employing X-ray crystallography, nuclear magnetic resonance spectroscopy, and three-dimensional quantitative structure activity relationship analysis, is creating highly specific, biologically active molecules by virtual reality modeling. Sophisticated screening technologies are eliminating all but the most active lead compounds. These new technologies promise more efficacious, safe, and cost-effective medications, while minimizing drug development time and maximizing profits.

Biotechnology↗

Pharmaceutical profiling in drug discovery.

Drug discovery research organizations are building capability for measuring an ensemble of crucial 'drug-like' properties. These structure-property relationship (SPR) data complement current SAR information. This pharmaceutical profiling strategy enables research teams to better plan and interpret discovery experiments, be alerted to potential 'show stoppers', improve property liabilities, and select the best candidates for advancement. High throughput property assays for physicochemical properties--solubility, permeability, lipophilicity, stability, and pK(a)--in vitro ADME--metabolism, transporters, protein binding and CYP inhibition--and in vivo PK/exposure provide a wealth of data for teams to make informed decisions.

Animals↗

Drug-drug interactions of anti-infective drugs: utility of fluorescence cyp inhibition assays in drug discovery.

Drug interactions are often a result of induction or inhibition of cytochrome P450 (CYP) enzymes by co-administered drugs. A high throughput fluorescence assay using cDNA-expressed human CYP isozymes and fluorogenic substrates has been reported for the study of CYP inhibition. We used this assay to evaluate CYP inhibition profiles of 21 marketed anti-infective drugs. We found that six of the eight potent inhibitors identified in this screen (IC50 <10 microM against at least one CYP isozyme) correlated with significant drug-drug interactions in the clinic. In contrast, the intermediate and weak inhibitors (IC50 >10 microM) did not indicate clinically significant drug interactions. Furthermore, we observed that results obtained in the fluorescence assay correlated with conventional, well-established, low throughput methods that utilize human liver microsomes. These data suggest that in the early stages of drug discovery, the fluorescence assay for CYP inhibition could be used in conjunction with a human liver microsomal assay to identify new chemical entities with a potential for drug-drug interactions.

Anti-Infective Agents↗

Exploiting marine actinomycete biosynthetic pathways for drug discovery.

Drug discovery relies on the generation of large numbers of structurally diverse compounds from which a potential candidate can be identified. To this end, actinomycetes have often been exploited because of their ability to biosynthesize an impressive array of novel metabolites particularly polyketides. The genetic organization of polyketide synthases (PKSs) makes them readily amenable to manipulation, and thus re-engineering artificial or hybrid PKSs to produce unnatural natural products is a reality. This review highlights two approaches we have used to generate novel polyketides by manipulating genes responsible for starter unit biosynthesis in the 'Streptomyces maritimus' enterocin type II PKS. Our preliminary investigation into the biosynthesis of neomarinone, a rare marine actinomycete-derived meroterpenoid, is also presented.

Actinobacteria↗

Automated analysis of large sets of heteronuclear correlation spectra in NMR-based drug discovery.

Drug discovery procedures based on NMR typically require the analysis of thousands of NMR spectra. For example, in "SAR by NMR", two-dimensional NMR spectra are recorded for a target protein mixed with ligand candidates from a comprehensive library of small molecules and are compared to the corresponding spectrum for the protein alone. We present an automated procedure for the comparative analysis of large sets of heteronuclear single quantum coherence spectra, which is based on three-way decomposition and implemented as the software package MUNIN. In a single step, spectra with differences in the peak positions (indicating ligand binding) and the affected peaks are identified. By omission of peak picking, ad hoc scoring of the quality of doubtful peaks is avoided. The procedure has been tested on the bacterial ribonuclease barnase, with a protein concentration of only 50 microM, using several small molecules including the substrate analogue 3'-GMP. Sets of 51 spectra were processed simultaneously, and it is concluded that spectra with binding ligands can be unambiguously identified from much larger sets of spectra.

Bacterial Proteins↗

Toxicogenomics in drug discovery and drug development: potential applications and future challenges.

Despite the massive investments made by pharmaceutical companies on drug research and development, the number of new drug approvals has remained stagnant in the past decades. It is well known that developing safe and effective new drugs is a long, difficult, and expensive process. While the cost of developing new drugs is increasing rapidly, withdrawals of drugs from the marketplace due to adverse drug reactions (ADR) and/or toxicity is increasing concurrently. The recent advent of high-throughput in silico (computer softwares) and in vitro (cell cultures) screenings have somewhat alleviated some, but not all, of these challenges by providing an efficient and effective way for developing safer and better drugs. This emerging technology, known as toxicogenomics, has great potential to facilitate the development of methodologies that could predict the long-term toxic effects of compounds using relatively short-term bioassays. This review is aimed at discussing the potential applications and future challenges of toxicogenomics in drug discovery and drug development.

Animals↗

Barriers to Alzheimer disease drug discovery and drug development in the pharmaceutical industry.

The drug development process in the pharmaceutical industry has evolved from separate programs, specific for each country, into one coordinated, global development scheme. As a result, such a development program must meet regulatory requirements for all countries in which approval for the new drug will be sought. Barriers to Alzheimer disease (AD) drug discovery and development in the pharmaceutical industry can be categorized as (1) regulatory, (2) logistical, and (3) drug development issues. Some of the regulatory barriers could be overcome by international harmonization of guidelines for the development of antidementia drugs. The logistical issues can be reduced through international collaboration in the conduct of clinical studies, and the developmental issues can be addressed by using an expedited drug development plan that not only can reduce the time but also the resources required to develop the drug.

Alzheimer Disease↗

Positron Emission Tomography: applications in drug discovery and drug development.

Positron Emission Tomography (PET) is a sophisticated nuclear imaging modality that affords researchers the ability to conduct both functional and molecular imaging on biological and biochemical processes in vivo. In functional imaging, biological parameters such as metabolic rate and perfusion that can be altered by disease or treatment are monitored. In molecular imaging, PET can be used to examine and quantify cellular events such as cell trafficking, receptor binding and gene expression. Therefore, PET is an important tool to elucidate mechanisms associated with diseases and drug actions. In addition to PET, microPET is designed to image small animals. A great tool to facilitate preclinical studies and basic research, it can eliminate the need of sacrificing the animal by enabling noninvasive, longitudinal, and serial studies. The results from preclinical studies using microPET can be directly correlated with clinical studies using PET, thus bridging the chasm that used to separate the 2 pivotal phases in drug development. This review first describes the basic principles of PET and compares it to other imaging modalities. Then, PET procedures and PET isotopes and tracers synthesis are outlined. Next, functional and molecular PET imaging applications in the fields of oncology, neurology, and cardiology in both humans and animals are presented. Spanning a wide range, these applications demonstrate the versatility of PET and how it can be used to accelerate drug discovery and development. Finally, the advantages and limitations of PET and how it can be used in the future to minimize risks of drug development are discussed.

Animals↗

The application of in vitro models of drug metabolism and toxicity in drug discovery and drug development.

In vitro models are being used increasingly during all phases of the drug development process in concert with the more traditional in vivo toxicological and pharmacokinetic evaluations. These in vitro models may be classified empirically as either validated in vitro screens, value-added screens or 'ad-hoc' mechanistic screens. The application of these screens is discussed with respect to their level of validation, standardization, uses of human tissue, level of iteration with in vivo studies, regulatory position and utility in the drug discovery and development process. The predictability and reproducibility of these screens is discussed, as well as future trends in regard to emerging technology and its application.

Animals↗