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PubMed2003

Keystone symposia: antibody-based therapeutics for cancer.

This important conference focused on the latest developments in therapeutic antibodies, particularly for their design, production and formulation for cancer therapy. Engineered antibodies currently represent over 30% of biopharmaceuticals in clinical trials, highlighted by the recent FDA approvals of Zevalin (ibritumomab tiuxetan, IDEC Pharmaceuticals) for cancer radioimmunotherapy and Humira (adalimumab, Abbott Laboratories) for rheumatoid arthritis [1,2]. An impressive array of international speakers was assembled in Banff by the organisers L Weiner (Fox Chase Cancer Center, USA) and P Carter (Amgen and Seattle Genetics). The meeting highlighted emerging new technologies, both for the discovery of novel cancer biomarkers and for innovative immunotherapeutic designs. The latest successes were also presented for antibodies directed to the conventional cancer targets, including CD20, carcinoembryonic antigen (CEA), erbB-family proteins and vascular endothelial growth factor (VEGF). Importantly, recent structural details emerged that will direct future designs of these cancer-targeting molecules, ranging from antibody-dependent cellular-cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) enhancement to improved cytotoxic payloads using radionuclides, toxins, enzymes, drugs and viral delivery. The conference also highlighted the latest in vitro antibody libraries for the selection of high-affinity reagents against refractory cancer targets, and included the design of small domain modules for highly-efficient in vivo targeting to large, high avidity complexes for enhanced cytotoxicity. The major challenges in this rapidly growing area include the need to initiate and sustain innate and adaptive immune responses for the generation of efficient, long-term tumour therapy. This conference was sponsored by Amgen and accredited by the Accreditation Council for Continuing Medical Education (ACCME).

Animals↗

PubMed2003

Cambridge Healthtech Institute's 5th Annual 'Molecular Display: The Chemistry Set for Proteins and Small Molecules' Conference.

This meeting covered recent advances in the molecular display of peptides, proteins and nucleotides, including selection and mutational technologies. The scientific organisers assembled an impressive array of 'molecular display' heavyweights. It promised to be a stimulating meeting and the events of the following 2 days did not disappoint. The majority of the presentations were concerned with the development of novel display technologies and processes. Antibodies currently represent > 30% of the biopharmaceutical market, but are likely to be superseded by more efficient display frameworks which avoid their inherent drawbacks. In order to generate such novel therapeutics and diagnostics, high affinity reagents must be selected and/or generated from hitherto unexplored nucleic acid sequences and displayed on suitable frameworks. This meeting was concerned with the identification, generation and validation of novel sequences and framework molecules. The keynote addresses were followed by four themed sessions entitled New technologies and target selection, The discovery of small molecules using phage display, Applications in proteomics, and Novel therapeutics and diagnostics. There was a panel discussion after each session.

Drug Design↗

PubMed2005

Medicinally useful proteins--enhancing the probability of technical success in the clinic.

Proteins that are normally present in organisms function to maintain the overall homeostatic balance of the living system. Although an understanding of the biology of these proteins is essential to determining their utility in the treatment of disease, the administration of wild-type forms of proteins in a therapeutic manner (often systemically and at concentrations much higher than those found in the healthy organism) can have the effect of inappropriate activation of cell types and compartments that can lead to an undesirable response. Modification of the sequence of the parent protein to yield selected biological properties can generate derivative versions (muteins) having an optimal therapeutic profile. In addition to consideration of the biological properties, protein therapeutics are typically not active when delivered orally. This can limit the frequency with which the therapeutic agent can be administered to the patient, exemplifying the need to understand the pharmacokinetic and pharmacodynamic relationships of the protein. The biophysical properties of the mutein (e.g., solubility and stability) must also be considered in this context. An additional consideration with therapeutic proteins, engineered or not, is the potential immune response resulting from sequence variation and/or exogenous presentation to the immune system. The composite application of these principles to therapeutic protein discovery and development drives the ultimate success of any given biopharmaceutical agent.

Humans↗

PubMed2006

Ribosome display for improved biotherapeutic molecules.

Ribosome display presents an innovative in vitro technology for the rapid isolation and evolution of high-affinity peptides or proteins. Displayed proteins are bound to and recovered from target molecules in multiple rounds of selection in order to enrich for specific binding proteins. No transformation step is necessary, which could lead to a loss of library diversity. A cycle of display and selection can be performed in one day, enabling the existing gene repertoire to be rapidly scanned. Proteins isolated from the panning rounds can be further modified through random or directed molecular evolution for affinity maturation, as well as selected for characteristics such as protein stability, folding and functional activity. Recently, the field of display technologies has become more prominent due to the generation of new scaffolds for ribosome display, isolation of high-affinity human antibodies by phage display, and their implementation in the discovery of novel protein-protein interactions. Applications for this technology extend into the broad field of antibody engineering, proteomics, and synthetic enzymes for diagnostics and therapeutics in cancer, autoimmune and infectious diseases, neurodegenerative diseases and inflammatory disorders. This review highlights the role of ribosome display in drug discovery, discusses advantages and disadvantages of the system, and attempts to predict the future impact of ribosome display technology on the development of novel engineered biopharmaceutical products for biological therapies.

Animals↗

PubMed2004

Innovative therapeutics: from molecules to medicines. 27 June-7 July 2004, Parma, Italy.

The Socrates Intensive Programme offers annual courses focusing on the specific aspects of innovative therapeutics. The 2004 meeting was coordinated by the University of Parma and covered various subjects in the field of advanced drug delivery and pharmaceutical technology, including sessions on biopharmaceutics, pharmacokinetics, polymers, oral delivery, colloidal vectors, peptide and protein delivery, vaccines, oligonucleotide delivery, gene delivery, non-conventional routes of administration, and a graduate student symposium. The meeting had a highly interactive character and provided a unique opportunity for young scientists to present and discuss their work in an international setting.

Drug Administration Routes↗

PubMed2005

Buccal drug delivery.

Buccal formulations have been developed to allow prolonged localised therapy and enhanced systemic delivery. The buccal mucosa, however, while avoiding first-pass effects, is a formidable barrier to drug absorption, especially for biopharmaceutical products (proteins and oligonucleotides) arising from the recent advances in genomics and proteomics. The buccal route is typically used for extended drug delivery, so formulations that can be attached to the buccal mucosa are favoured. The bioadhesive polymers used in buccal drug delivery to retain a formulation are typically hydrophilic macro-molecules containing numerous hydrogen bonding groups. Newer second-generation bioadhesives have been developed and these include modified or new polymers that allow enhanced adhesion and/or drug delivery, in addition to site-specific ligands such as lectins. Over the last 20 years a wide range of formulations has been developed for buccal drug delivery (tablet, patch, liquids and semisolids) but comparatively few have found their way onto the market. Currently, this route is restricted to the delivery of a limited number of small lipophilic molecules that readily cross the buccal mucosa. However, this route could become a significant means for the delivery of a range of active agents in the coming years, if the barriers to buccal drug delivery are overcome. In particular, patient acceptability and the successful systemic delivery of large molecules (proteins, oligonucleotides and polysaccharides) via this route remains both a significant opportunity and challenge, and new/improved technologies may be required to address these.

Absorption↗

PubMed2005

The potential of chitosan for the oral administration of peptides.

Over recent years, a major challenge in drug delivery has been the design of appropriate vehicles for the oral administration of macromolecular drugs (peptides and proteins). Indeed, despite the increasing market value of these complex molecules, their clinical use has been highly limited by their reduced oral bioavailability. Among the different delivery approaches explored so far, those based on the use of the polysaccharide chitosan have opened promising alternatives towards this ambitious goal. This is due to the interesting physicochemical and biopharmaceutical properties of this polymer. This article describes the advances that have been made in the design of chitosan-based systems specially adapted for the oral administration of peptides. These systems include solutions, microspheres, nanoparticles, nanocapsules and liposomes. More specifically, this article discusses the efficacy of the different delivery approaches for improving the absorption of peptides, and analyses the various mechanisms that have been proposed for the understanding of their efficacy.

Administration, Oral↗

PubMed2004

Pharmaceutical stability testing conference.

The Pharmaceutical Stability Testing conference organised by SMi was held on the 8th and 9th of September 2003 in London. The focus of the conference was on stability testing issues related to both compound drugs and biopharmaceuticals and the impact of stability testing on product development and commercialisation. The conference brought two days of presentations given by formulation, process, analytical, quality and regulatory professionals from both the European and US pharmaceutical industries. The presentations discussed various issues related to pharmaceutical stability testing in early stage preclinical development, during clinical studies and in late stage development for regulatory filing. The discussions covered biologicals and small molecules, drug substance and drug product, with supporting case studies.

Drug Approval↗

PubMed2005

Ribosome display: next-generation display technologies for production of antibodies in vitro.

Antibodies represent an important and growing class of biologic research reagents and biopharmaceutical products. They can be used as therapeutics in a variety of diseases. With the rapid expansion of proteomic studies and biomarker discovery, there is a need for the generation of highly specific binding reagents to study the vast number of proteins encoded by the genome. Display technologies provide powerful tools for obtaining antibodies. Aside from the preservation of natural antibody repertoires, they are capable of exploiting diversity by DNA recombination to create very large libraries for selection of novel molecules. In contrast to in vivo immunization processes, display technologies allow selection of antibodies under in vitro-defined selection condition(s), resulting in enrichment of antibodies with desired properties from large populations. In addition, in vitro selection enables the isolation of antibodies against difficult antigens including self-antigens, and this can be applied to the generation of human antibodies against human targets. Display technologies can also be combined with DNA mutagenesis for antibody evolution in vitro. Some methods are amenable to automation, permitting high-throughput generation of antibodies. Ribosome display is considered as representative of the next generation of display technologies since it overcomes the limitations of cell-based display methods by using a cell-free system, offering advantages of screening larger libraries and continuously expanding new diversity during selection. Production of display-derived antibodies can be achieved by choosing one of a variety of prokaryotic and eukaryotic cell-based expression systems. In the near future, cell-free protein synthesis may be developed as an alternative for large-scale generation of antibodies.

Antibodies↗

PubMedDate not supplied

Opportunities and constraints in schistosomiasis vaccine development: infection characteristics and industry realities.

The notes provided in this article relate to two components of the development of vaccines against schistosomiasis: (1) The characteristics of schistosome infections (eg. features of the schistosome life cycle), and the parasite itself, that have implications for vaccination strategies; (2) The characteristics of the biopharmaceutical industry that have implications for product development. As will be seen, these two topic areas are not vastly disparate.

Animals↗

PubMed2000

Economic and humanistic impact of adverse events associated with CSFs.

The current economic health care environment is causing considerable challenges for hospital pharmacy. As pharmacy managers attempt to deal with managing the costs associated with pharmaceuticals, there is considerable pressure to account for the clinical outcomes associated with drug therapy. Particularly in cancer treatment as high-cost biopharmaceuticals have infiltrated the care of these patients, pharmacy managers must account for reimbursement issues, clinical outcomes, patient satisfaction and demands, budgetary costs, and appropriate use of costly resources. Consequently, managers need to develop strategies to address these concerns. Ideally, pharmacoeconomics should be used to incorporate the costs of clinical outcomes and drug costs into the overall evaluation of drug therapy. Unfortunately, for a variety of reasons, the practical application of pharmacoeconomics is not universally employed and, as a result, most evaluations rely on only drug costs. A method to assess the economic impact of clinical outcomes associated with adverse drug events and cancer chemotherapy is described.

Antineoplastic Agents↗

PubMed2000

Absorption of phenytoin from rectal suppositories formulated with a polyethylene glycol base.

STUDY OBJECTIVE: To compare phenytoin pharmacokinetics following administration of an oral suspension and a rectal suppository formulated with a polyethylene glycol base. DESIGN: Unblinded, single-dose, randomized, crossover trial. SETTING: University-affiliated pharmacokinetics and biopharmaceutics laboratory. SUBJECTS: Six healthy subjects. INTERVENTION: Subjects were given a single 200-mg dose of phenytoin as an oral suspension and a rectal suppository separated by a 1-week washout. MEASUREMENTS AND MAIN RESULTS: Blood for plasma phenytoin concentrations was obtained at baseline and 0.5, 1, 2, 4, 6, 8, 10, 12, and 24 hours after administration. Plasma was analyzed by high-performance liquid chromatography (coefficient of variation < 6%) for total phenytoin concentration. Phenytoin maximum concentration (Cmax), time to Cmax (Tmax), time to first measurable concentration (Tlag), and area under the curve from time zero to time of last measurable concentration (AUClast) were estimated for oral and rectal administration by WinNonlin (v 1.1) and compared using Wilcoxon's signed rank test (p<0.05 for statistical significance). Two subjects did not have detectable plasma phenytoin concentrations after rectal administration. For the other four subjects, median rectal Cmax was significantly lower than oral Cmax (0.4 vs 1.9 microg/ml, p=0.028), median rectal Tmax did not differ from oral Tmax (11.9 vs 8.0 hrs, p=0.465), and median rectal AUClast, although highly variable, was significantly lower than oral AUClast (5.4 vs 36.2 microg x hr/ml, p=0.046). No Tlag was seen after oral administration, but with rectal administration the median Tlag was 2 hours. The estimated relative bioavailability of rectal phenytoin suppositories based on AUC0-24 was 4.7%, with individual values ranging from 0-58.3%. CONCLUSION: It appears that absorption of phenytoin from polyethylene glycol rectal suppositories in healthy subjects is highly variable and unpredictable. Thus this formulation is not recommended.

Administration, Rectal↗

PubMed2003

Advances in the pharmacotherapy of attention-deficit-hyperactivity disorder: focus on methylphenidate formulations.

The psychostimulant dl-methylphenidate (MPH) remains the most common drug therapy in child and adolescent psychiatry for the treatment of attention-deficit-hyperactivity disorder (ADHD). Evidence of a dopaminergic basis both for the actions of MPH and for the underlying neuropathology in ADHD continues to mount. Advances in the biopharmaceutics of MPH have been conspicuous. Novel approaches to formulation design have resulted in new MPH delivery options to overcome the short-term actions of both immediate-and sustained-release MPH. New modified-release MPH products offer the convenience of once-daily administration while providing extended absorption profiles that better mimic those of standard schedules of immediate-release MPH (i.e., the absorption phase of MPH better correlates with improved behavioral response than does the elimination phase). The oral bioavailability of MPH in females may be lower than in males. The l-MPH isomer exhibits only negligible oral bioavailability and, further, possesses little intrinsic activity at the dopamine transporter. This notwithstanding, a single-isomer d-MPH immediate-release product is now available for dosing recommended at one-half that of dl-MPH.

Attention Deficit Disorder with Hyperactivity↗

PubMed2005

Relationships between the concentrations of prostaglandins and the nonsteroidal antiinflammatory drugs indomethacin, diclofenac, and ibuprofen.

STUDY OBJECTIVES: To study the concentration-effect relationships of the nonsteroidal antiinflammatory drugs (NSAIDs) indomethacin, diclofenac, and ibuprofen; to investigate whether standard doses of these drugs inhibit prostaglandin concentrations to a similar extent, determined by measuring the concentration of a surrogate marker of prostaglandin E 2 (PGE 2 ); and to determine the extent to which dose increases produce analogous increases in prostaglandin inhibition. DESIGN: Single-dose, randomized, crossover trial with a 1-week washout period. SETTING: University biopharmaceutics and pharmacokinetics laboratory. SUBJECTS: Eight healthy adult volunteers younger than 35 years old. INTERVENTION: Subjects were administered two different standard doses of regular formulations (not enteric coated) of each NSAID on separate occasions. MEASUREMENTS AND MAIN RESULTS: Plasma samples were collected for determination of drug and 13,14-dihydro-15-keto-PGE 2 (PGEM; the surrogate marker of PGE 2 ) concentrations at regular intervals after administration of each NSAID dose. Statistically significant linear correlations were found between the percent reduction in PGEM concentration and the concentrations of diclofenac, indomethacin, and ibuprofen in plasma (R 2 = 0.992-0.999). The PGEM plasma concentrations correlated inversely with NSAID plasma concentrations, indicating maximum inhibition when the highest NSAID plasma concentrations were achieved. Statistically significant differences in the percent inhibition of PGEM concentrations were observed between the two doses for each NSAID (p<0.05), but not between subjects for each NSAID. Doubling the dose (100% increase) of diclofenac and indomethacin produced a 60-65% increase in maximum inhibition of PGEM concentrations, whereas a 50% increase in dose produced a 44% increase in the maximum effect of ibuprofen. CONCLUSION: Prostaglandin inhibition, as measured by changes in PGEM concentrations, correlated significantly with NSAID concentrations in plasma and differed significantly between high and low NSAID doses. Measurement of PGEM plasma concentrations appears to be a promising marker for estimation of relative potency of NSAIDs.

Administration, Oral↗

PubMed2003

Remote controlled capsules in human drug absorption (HDA) studies.

The biopharmaceutical complexity of today's new drug candidates provides significant challenges for pharmaceutical scientists in terms of both candidate selection and optimizing subsequent development strategy. In addition, life cycle management of marketed drugs has become an important income stream for pharmaceutical companies, but the selection of least risk/highest benefit strategies is far from simple. The proactive adoption of human drug absorption (HDA) studies using remote controlled capsules offers the pharmaceutical scientist significant guidance for planning a route through the maze of product development. This review examines the position of HDA studies in drug development, using a variety of case histories and an insightful update on remote controlled capsules to achieve site-specific delivery.

Capsules↗

PubMed2004

Amorphous drug delivery systems: molecular aspects, design, and performance.

The biopharmaceutical properties-especially the solubility and permeability-of a molecule contribute to its overall therapeutic efficacy. The newer tools of drug discovery have caused a shift in the properties of drug-like compounds, resulting in drugs with poor aqueous solubility and permeability, which offer delivery challenges, thus requiring considerable pharmaceutical manning. The modulation of solubility is a more viable option for enhancing bioavailability than permeability, because of the lack of "safe" approaches to enhance the latter. Solid-state manipulation in general, and amorphization in particular, are preferred ways of enhancing solubility and optimizing delivery of poorly soluble drugs. This review attempts to address the diverse issues pertaining to amorphous drug delivery systems. We discuss the various thermodynamic phenomenon such as glass transition, fragility, molecular mobility, devitrification kinetics, and molecular-level chemical interactions that contribute to the ease of formation, the solubility advantage, and the stability of amorphous drugs. The engineering of pharmaceutical alloys by solubilizing and stabilizing carriers, commonly termed solid dispersions, provide avenues for exploiting the benefits of amorphous systems. Carrier properties, mechanisms of drug release, and study of release kinetics help to improve the predictability of performance. The review also addresses the various barriers in the design of amorphous delivery systems, use of amorphous form in controlled release delivery systems, and their in vivo performance.

Adjuvants, Pharmaceutic↗

PubMed2004

Recent developments in the use of bioadhesive systems for delivery of drugs to the oral cavity.

The delivery of therapeutic agents to, or via, the oral cavity is limited by the efficient removal mechanisms that exist in this area. Bioadhesive formulations have been developed to allow prolonged localized therapy and enhanced systemic delivery. The oral mucosa however, while avoiding first-pass effects, is a formidable barrier to drug absorption, especially for "biopharmaceutical" products arising from the recent innovations in genomics and proteomics. Bioadhesive polymers are typically hydrophilic macromolecules containing numerous hydrogen-bonding groups. Second-generation bioadhesives include modified or new polymers that allow enhanced adhesion and/or drug delivery, along with site-specific ligands such as lectins. Over the last 20 years, a range of bioadhesive formulations have been developed for the oral cavity, but only comparatively few have found their way onto the market. This review will consider some recent developments in the use of bioadhesive buccal systems, notably the development of new polymers, advanced delivery systems, and the exploitation of the multifunctional properties of some bioadhesives.

Adhesives↗

PubMed2005

Modification of epithelial tight junction integrity to enhance transmucosal absorption.

Tight junctions (TJs) located between adjacent epithelial cells restrict the movement of solutes, ions, and even water. Restriction of macromolecules by TJ structures impedes one potential route of absorption for biopharmaceutical drugs, a route known as the paracellular pathway. It is anticipated that an improved understanding of TJ structure and cellular mechanisms that regulate its function will lead to successful strategies for improved transmucosal drug absorption through the paracellular pathway. Based upon clinical correlations between TJ dysfunction and several disease states, any approach to modify TJ integrity to enhance drug absorption in this way must be tempered by an appreciation of potential safety concerns that might develop through sustained or repeated TJ alterations. This review describes a current understanding of epithelial TJ organization and examines potential methods and implications for regulated modification of TJ function for the enhanced uptake of drugs without detrimental clinical outcomes.

Amino Acid Sequence↗