Changes of neonatal mortality rate between 'pre' and 'post' surfactant period.
The objective of this study was to determine how the neonatal mortality rate has changed since surfactant (S) therapy was introduced in our Neonatal Intensive Care Unit (NICU), and to evaluate the efficacy of surfactant therapy in respiratory distress syndrome (RDS) patients. Incidences of risk babies such as outborns, prematurity, low birth weight infants and RDS, and neonatal mortality rates were compared between 'pre' (control, 1988 to 1991, n=4,861) and 'post' S period (study, 1993 to 1996, n=5,430). In RDS patients of 'post' S period, neonatal mortality rate was compared between S-treated and non-treated patients, and chest X-ray and ventilatory parameters were compared between pre- and post-72 hr of surfactant treatment. Surfactant therapy showed short term effects, judging by the decrease of early neonatal deaths and improvement of chest X-ray and ventilatory parameters in RDS patients. The overall neonatal mortality rate had a tendency to decrease in spite of increased incidences of risk babies in 'post' S period but it was less than expected. The reasons were thought to be that we had a high proportion of risk babies, and there was some bias in patient selection for surfactant therapy and its use. In conclusion, with the active prevention of risk baby delivery and appropriate use of surfactant, better results could be expected. (+info)
Surfactant treatment for acute respiratory distress syndrome.
OBJECTIVE: To determine prospectively the efficacy of surfactant in acute respiratory distress syndrome. STUDY DESIGN: Twenty patients, 1 month to 16 years of age, diagnosed with an acute pulmonary disease with severe hypoxaemia (PaO2/FiO2 < 100) (13 with systemic or pulmonary disease and seven with cardiac disease) were treated with one to six doses of 50-200 mg/kg of porcine surfactant administered directly into the trachea. The surfactant was considered to be effective when the PaO2/FiO2 improved by > 20%. RESULTS: After initial surfactant administration the PaO2/FiO2 increased significantly in patients with systemic or pulmonary disease from 68 to 111, and the oxygenation index (OI) diminished significantly from 36.9 to 27.1. The PaO2/FiO2 and OI did not improve in children with cardiac disease. The improvement of the patients who survived was greater than that of those who died. CONCLUSIONS: Surfactant moderately improves oxygenation in some children with severe acute respiratory distress syndrome secondary to pulmonary or systemic disease. (+info)
Preclinical development strategies for novel gene therapeutic products.
With over 220 investigational new drug applications currently active, gene therapy represents one of the fastest growing areas in biotherapeutic research. Initially conceived for replacing defective genes in diseases such as cystic fibrosis or inborn errors of metabolism with genes encoding the normal, or wild-type, gene product, gene therapy has expanded into other novel applications such as treatment of cancer or cardiovascular disease, where the risk:benefit profiles may be more acceptable in relation to the severity of the disease. Different types of vectors, including modified retroviruses, adenoviruses, adenovirus-associated viruses, and herpesviruses and plasmid DNA, are used to transfer foreign genetic material into patients' cells or tissues. Developing a toxicology program to determine the safety of these agents, therefore, requires a modified approach that encompasses the pharmacology and toxicity of both the gene product itself and the vector system used for delivery in the context of the application for the clinical trial. In general, the issues involved in designing and developing appropriate preclinical testing to determine the safety of these products are similar to those encountered for other recombinant molecules, including protein biotherapeutics. Limitations to some of the typical toxicology studies conducted for a traditional drug development program may exist for these agents, and nontraditional approaches may be required to demonstrate their safety. Many factors may affect the safety and clinical activity of these agents, including the route, frequency, and duration of exposure and the type of vector employed. Other safety considerations include quantitation of the duration and degree of expression of the vector in target and other tissues, the effects of gene expression on organ pathology and/or histology, evaluation of trafficking of gene-transduced cells or vector after injection, and interactions of the host immune system with the transduced cell population. Because of the unique concerns regarding each of these therapies, the Center for Biologics Evaluation and Research encourages sponsors to obtain toxicity data whenever possible while evaluating the pharmacologic activity of the vector in a species or animal model relevant to their clinical indication. Sponsors are encouraged to discuss preclinical study design and results with the Center during product development to facilitate early identification of safety concerns prior to entry of these novel agents into the clinical setting and to ensure an uninterrupted course of development while addressing issues required for licensure. (+info)
Regulatory decision strategy for entry of a novel biological therapeutic with a clinically unmonitorable toxicity into clinical trials: pre-IND meetings and a case example.
The following material was derived from a synthesis of case histories taken from investigational new drug (IND) applications and drug sponsors' experiences, utilizing fictionalized data to avoid any resemblance to any proprietary information; any such resemblance is accidental. These examples are used as an instructional scenario to illustrate appropriate handling of a difficult toxicology issue. In this scenario, a drug caused a toxicity in animals that was detected only by histopathologic analysis; if it were to develop in patients, no conventional clinical methods could be identified to monitor for it. It is not unusual for a firm to cancel clinical development plans for a lead drug candidate that causes such a toxicity, especially if such a drug is intended for use as a chronic therapeutic in a population of patients with a chronic disease. This case synthesis was inspired by a Food and Drug Administration (FDA) agreement to allow such a product to proceed into clinical trials after substantive pre-IND discussions and agreement on well-considered toxicology program designs. The scientists most closely involved in the strategy development included the sponsor's toxicologist, veterinary toxicologic pathologist, and pharmacokineticist, as well as the FDA's reviewing pharmacologist. The basis of this decision was thorough toxicity characterization (1-month studies in 2 species); correlating toxicities with a particular cumulative area under the curve (AUC) in both species; identification of the most sensitive species (the species that showed the lower AUC correlating with toxicity); allometric assessment of clearance of the drug in 3 nonhuman species; construction of a model of human kinetics (based on extrapolation from animal kinetics); and finally, estimation of clinical safety factors (ratios of the human estimated cumulative AUC at the proposed clinical doses, over the animal cumulative AUC that correlated with the no adverse effect levels). Industry and FDA scientists negotiated a joint assessment of risk and benefit in patients, resulting in the FDA permitting such a compound to enter into clinical trials for a serious autoimmune disease. Such constructive, early communication starts with the pre-IND meeting, and the conduct and planning for this meeting can be very important in establishing smooth scientific and regulatory groundwork for the future of a drug under IND investigation. (+info)
Safety assessment of biotechnology-derived pharmaceuticals: ICH and beyond.
Many scientific discussions, especially in the past 8 yr, have focused on definition of criteria for the optimal assessment of the preclinical toxicity of pharmaceuticals. With the current overlap of responsibility among centers within the Food and Drug Administration (FDA), uniformity of testing standards, when appropriate, would be desirable. These discussions have extended beyond the boundaries of the FDA and have culminated in the acceptance of formalized, internationally recognized guidances. The work of the International Committee on Harmonisation (ICH) and the initiatives developed by the FDA are important because they (a) represent a consensus scientific opinion, (b) promote consistency, (c) improve the quality of the studies performed, (d) assist the public sector in determining what may be generally acceptable to prepare product development plans, and (e) provide guidance for the sponsors in the design of preclinical toxicity studies. Disadvantages associated with such initiatives include (a) the establishment of a historical database that is difficult to relinquish, (b) the promotion of a check-the-box approach, i.e., a tendancy to perform only the minimum evaluation required by the guidelines, (c) the creation of a disincentive for industry to develop and validate new models, and (d) the creation of state-of-the-art guidances that may not allow for appropriate evaluation of novel therapies. The introduction of biotechnology-derived pharmaceuticals for clinical use has often required the application of unique approaches to assessing their safety in preclinical studies. There is much diversity among these products, which include the gene and cellular therapies, monoclonal antibodies, human-derived recombinant regulatory proteins, blood products, and vaccines. For many of the biological therapies, there will be unique product issues that may require specific modifications to protocol design and may raise additional safety concerns (e.g., immunogenicity). Guidances concerning the design of preclinical studies for such therapies are generally based on the clinical indication. Risk versus benefit decisions are made with an understanding of the nature of the patient population, the severity of disease, and the availability of alternative therapies. Key components of protocol design for preclinical studies addressing the risks of these agents include (a) a safe starting dose in humans, (b) identification of potential target organs, (c) identification of clinical parameters that should be monitored in humans, and (d) identification of at-risk populations. One of the distinct aspects of the safety evaluation of biotechnology-derived pharmaceuticals is the use of relevant and often nontraditional species and the use of animal models of disease in preclinical safety evaluation. Extensive contributions were made by the Center for Biologics Evaluation and Research to the ICH document on the safety of biotherapeutics, which is intended to provide worldwide guidance for a framework approach to the design and review of preclinical programs. Rational, scientifically sound study design and early identification of the potential safety concerns that may be anticipated in the clinical trial can result in preclinical data that facilitate use of these novel therapies for use in humans without duplication of effort or the unnecessary use of animals. (+info)
Are there environmental forms of systemic autoimmune diseases?
A large number of drugs and an increasing number of environmental agents reportedly result in the appearance of a number of autoantibodies and in many instances in the appearance of a range of autoimmune clinical syndromes. The major disorders so recognized have marked resemblances to the autoimmune disease systemic lupus erythematosus. The commonly used term is drug-induced lupus; a better term is drug-related lupus. There is considerable interest at the present time in an increasing number of environmental agents. There have been two epidemics in recent years--one in Spain to a contaminant of rapeseed oil and one in the United States to a contaminant of l-tryptophan that caused an eosinophilic myositis. It is important for physicians and others involved in health care to recognize the potential associations of these diseases of unknown cause or causes. (+info)
The role of the toxicologic pathologist in the preclinical safety evaluation of biotechnology-derived pharmaceuticals.
Biotechnology-derived pharmaceuticals, or biopharmaceuticals, represent a special class of complex, high molecular weight products, such as monoclonal antibodies, recombinant proteins, and nucleic acids. With these compounds, it is not appropriate to follow conventional safety testing programs, and the preclinical "package" for each biopharmaceutical needs to be individually designed. In addition to standard histopathology, the use of molecular pathology techniques is often required either in conventional animal studies or in in vitro tests. In this review, the safety evaluation of biopharmaceuticals is discussed from the perspective of the toxicologic pathologist, and appropriate examples are given of the use of molecular pathology procedures. Examples include the use of in situ hybridization to localize gene therapy vectors, the assessment of vector integration into genomic DNA by the polymerase chain reaction (PCR), and the use of immunohistochemistry to evaluate the potential cross-reactivity of monoclonal antibodies. In situ PCR techniques may allow for confirmation of the germ cell localization of nucleic acids and may therefore facilitate the risk assessment of germline transmission. Increased involvement with biopharmaceuticals will present challenging opportunities for the toxicologic pathologist and will allow for much greater use of molecular techniques, which have a critical role in the preclinical development of these compounds. (+info)
Structures of surfactant films: a scanning force microscopy study.
The alveolar lining layer is thought to consist of a continuous duplex layer, i.e., an aqueous hypophase covered by a thin surfactant film which is a monolayer with dipalmitoyl-phosphatidylcholine (DPPC) as its most important component. Findings obtained by electron microscopy and results from in vitro experiments suggest, however, that the structure and hence the structure-function relations of surfactant films are more complex. In order to better define their structures films of surfactants were studied by scanning force microscopy. Four different surfactants were spread on a Langmuir-Wilhelmy balance, and then transferred onto a solid mica plate by the Langmuir-Blodgett technique, under various states of film compression. Imaging of the films by scanning force microscopy was performed in the contact (repulsive) mode in air. The scanning force micrographs revealed that surfactant films are not homogeneous, but rather undergo phase transitions depending on the surface pressures. Even at comparable surface pressures different surfactants show quite different surface patterns. Differences in surface structure can even be observed in films containing surfactant proteins (SP)-B and SP-C. These observations give further evidence that the widely accepted hypothesis of a regular monolayer of phospholipids governing the surface tension probably does not hold true, but that the structure-function relationship of surface active surfactant films is even more complex than hitherto thought. (+info)