Regulatory hurdles in bringing an in vitro diagnostic device to market

We discuss the hurdles that developers and manufacturers of in vitro diagnostic devices face in obtaining regulatory approval to market their products in the US. A thorough understanding of medical device regulation and the early planning of a clinical and regulatory strategy are imperative in assuring successful and timely launches of new products. Finally, it is critical for manufacturers to establish a working partnership with the Food and Drug Administration to expedite their new product applications.     

Physicians'' attitudes toward patients'' use of alternative cancer therapies

Glucuronide conjugates of arylamines are thought to be important in the carcinogenic process. This study investigated the pH stability and synthesis of glucuronide conjugates of 4-aminobiphenyl and its N-hydroxy metabolites by human and dog liver. Both dog and human liver slices incubated with 0.06 mM [3H]-4-aminobiphenyl produced the N-glucuronide of 4-aminobiphenyl as the major product. After 2 hr of incubation, the N-glucuronide of 4-aminobiphenyl represented 52 and 27% of the total radioactivity recovered by HPLC in dog and human, respectively. When 4-aminobiphenyl, N-hydroxy-4-aminobiphenyl, or N-hydroxy-N-acetyl-4-aminobiphenyl was added to human microsomes containing [14C]UDP-glucuronic acid, a new product peak was detected by HPLC. At 0.5 mM, the rate of glucuronidation was N-hydroxy-N-acetyl-4-aminobiphenyl > N-hydroxy-4-aminobiphenyl > 4-aminobiphenyl. The rate of formation of the N-glucuronide of 4-aminobiphenyl was similar to that observed with benzidine and N-acetylbenzidine. The glucuronides of 4-aminobiphenyl and N-hydroxy-4-aminobiphenyl were both acid labile with T1/2 values of 10.5 and 32 min, respectively, at pH 5.5. The glucuronide of N-hydroxy-N-acetyl-4-aminobiphenyl was not acid labile with T1/2 values at pH 5.5 and 7.4 of 55 and 68 min, respectively. The glucuronide of 4-aminobiphenyl was the most acid labile conjugate examined. Thus, the glucuronide of 4-aminobiphenyl is a major product of dog and human liver slice metabolism and likely to play an important role in the carcinogenic process.     

Analysis of a form of oxidative DNA damage, 8-hydroxy-2'-deoxyguanosine, as a marker of cellular oxidative stress during carcinogenesis

8-hydroxy-2'-deoxyguanosine (8-OH-dG) was first reported in 1984 as a major form of oxidative DNA damage product by heated sugar, Fenton-type reagents and X-irradiation in vitro. 8-OH-dG has been detected in cellular DNA using an HPLC-ECD method in many laboratories. Analyses of 8-OH-dG in animal organ DNA after the administration of oxygen radical-forming chemicals will be useful for assessments of their carcinogenic risk. Its analysis in human leucocyte DNA and in urine is a new approach to the assessment of an individual's cancer risk due to oxidative stress. The increase of the 8-OH-dG level in the cellular DNA, detected by HPLC-ECD method, was supported by its immunochemical detection and its enhanced repair activity. The validity of the general use of 8-OH-dG as a marker of cellular oxidative stress is discussed.     

Bone loss in Great Britain and Japan: a comparative longitudinal study

Benzenediazonium sulfate (BD) was given to Swiss mice by 26 subcutaneous injections of 10 micrograms/g body weight at weekly intervals. The treatment gave rise to tumors of the subcutis. The tumor incidences in the treated groups were 42% in females and 26% in males. The corresponding tumor incidences in the untreated controls were 0% in females and 2% in males. Histopathologically, the neoplasms were classified as fibrosarcomas, rhabdomyosarcomas, and osteosarcomas of the subcutaneous tissue. BD is formed during the cytochrome P-450 catalyzed metabolism of the carcinogenic 1-(phenylazo)-2-hydroxynaphthalene (Sudan I, Solvent Yellow 14), which was used as a coloring agent for food and other materials in several countries. Further, BD is a metabolic breakdown product of different classes of nitrogen-nitrogen bond- containing chemicals. BD is the fourth benzenediazonium salt found to be carcinogenic in this laboratory.     

Postmarketing surveillance: perspectives of a journal editor

In the absence of a systematic monitoring program for drugs newly approved by the Food and Drug Administration (FDA), reports in clinical journals provide a legitimate forum for disseminating information about unexpected pharmacologic events. A journal editor bears the responsibility for publishing educated clinical observations that meet standards of scientific rigor while not giving premature credibility to chance and dubious reports of side effects of new drugs. Often this responsibility involves overcoming the fear of bad publicity and withstanding pressures from pharmaceutical companies to print only positive information about new products. Published preliminary observations may contribute to the problem of product liability, but they also generate testable hypotheses and healthy debate. If hypotheses later prove to be incorrect, they can be refuted by systematic studies and clarified in reviews and editorials. Our goal of effective education will be reached not by self-censorship but by scientific openness.     

Pathogen Reduction and Hazard Analysis and Critical Control Point (HACCP) systems for meat and poultry. USDA

The United States Department of Agriculture (USDA) Food Safety Inspection Service (FSIS) adopted Hazard Analysis and Critical Control Point Systems and established finished product standards for Salmonella in slaughter plants to improve food safety for meat and poultry. In order to make significant improvements in food safety, measures must be taken at all points in the farm-to-table chain including production, transportation, slaughter, processing, storage, retail, and food preparation. Since pathogens can be introduced or multiplied anywhere along the continuum, success depends on consideration and comparison of intervention measures throughout the continuum. Food animal and public health veterinarians can create the necessary preventative environment that mitigates risks for food borne pathogen contamination.     

Formation of acrolein-derived 2'-deoxyadenosine adduct in an iron-induced carcinogenesis model

Acrolein is a representative carcinogenic aldehyde found ubiquitously in the environment and formed endogenously through oxidation reactions, such as lipid peroxidation and myeloperoxidase-catalyzed amino acid oxidation. It shows facile reactivity toward DNA to form an exocyclic DNA adduct. To verify the formation of acrolein-derived DNA adduct under oxidative stress in vivo, we raised a novel monoclonal antibody (mAb21) against the acrolein-modified DNA and found that the antibody most significantly recognized an acrolein-modified 2' -deoxyadenosine. On the basis of chemical and spectroscopic evidence, the major antigenic product of mAb21 was the 1,N6-propano-2' -deoxyadenosine adduct. The exposure of rat liver epithelial RL34 cells to acrolein resulted in a significant accumulation of the acrolein-2' -deoxyadenosine adduct in the nuclei. Formation of this adduct under oxidative stress in vivo was immunohistochemically examined in rats exposed to ferric nitrilotriacetate, a carcinogenic iron chelate that specifically induces oxidative stress in the kidneys of rodents. It was observed that the acrolein-2' -deoxyadenosine adduct was formed in the nuclei of the proximal tubular cells, the target cells of this carcinogenesis model. The same cells were stained with a monoclonal antibody 5F6 that recognizes an acrolein-lysine adduct, by which cytosolic accumulation of acrolein-modified proteins appeared. Similar results were also obtained from myeloperoxidase knockout mice exposed to the iron complex, suggesting that the myeloperoxidase-catalyzed oxidation system might not be essential for the generation of acrolein in this experimental animal carcinogenesis model. The data obtained in this study suggest that the formation of a carcinogenic aldehyde through lipid peroxidation may be causally involved in the pathophysiological effects associated with oxidative stress.     

Amination of tyrosine in liver cytosol protein of male F344 rats treated with 2-nitropropane, 2-nitrobutane, 3-nitropentane, or acetoxime

Previously, the secondary nitroalkane 2-nitropropane, a strong hepatocarcinogen in rats, had been shown to induce the formation of 8-aminoguanine in both DNA and RNA of rat liver through a sulfotransferase-mediated pathway. This pathway was postulated to convert the carcinogen into an aminating species [Sodum, R. S., et al. (1994) Chem. Res. Toxicol. 7, 344-351]. To submit this postulate to further test, we examined liver proteins of rats treated with 2-nitropropane, other carcinogenic secondary nitroalkanes, or the related rat liver tumorigen acetoxime for the presence of 3-aminotyrosine, the expected product of tyrosine amination. Using ion-pair and/or cation-exchange high-performance liquid chromatography with electrochemical detection, we found that the liver cytosolic proteins of these animals contained 0.1-1.5 mol of 3-aminotyrosine/10(3) mol of tyrosine. Treatment with the noncarcinogenic primary nitroalkane 1-nitropropane or with other primary nitroalkanes did not produce an analogous increase in the aminated amino acid (level of detection estimated at approximately 0.01 mol/10(3) mol of tyrosine). To our knowledge, this is the first report of the modification of protein tyrosine in vivo by a carcinogen. In vitro studies with acetoxime-O-sulfonate and hydroxylamine-O-sulfonate showed that these proposed intermediates in the activation pathway of 2-nitropropane react with guanosine to give 8-aminoguanosine, N1-aminoguanosine, and 8-oxoguanosine and also react with tyrosine to give 3-aminotyrosine and 3-hydroxytyrosine. The in vitro amination and oxidation of guanosine at C8 were also produced by acetophenoxime-O-sulfonate and 2-heptanoxime-O-sulfonate. These results provide additional evidence for the production of a reactive species capable of aminating nucleic acids and proteins from 2-nitropropane and other carcinogenic secondary nitroalkanes by a pathway involving oxime- and hydroxylamine-O-sulfonates as intermediates.     

Immune and endocrine regulation of food intake in sick animals

The evaluation of the carcinogenic potential of pharmaceuticals is currently undergoing dramatic changes. For the past 25 years the regulatory expectation for agents intended for long term use has been that lifespan studies (usually lasting 2 years) in 2 rodent species be conducted. These studies take at least 3 years to plan, execute and interpret, and use over 1200 animals. It is now recognised that the quality of the information obtained from these studies is unreliable for prediction of carcinogenic risk to humans. Over the past 4 years, the International Conference on Harmonisation (ICH) has recommended changes in approaches to assessing the carcinogenic potential of pharmaceuticals. In future, only one long term rodent study will be routinely required (usually in rats), provided this is complemented with a short or medium term test in one of the emerging new models for carcinogenicity, such as transgenic mice or newborn mice. However, the relevance of these new models to human cancer and their use in risk assessment is still largely unknown and this situation must be kept under review as knowledge accumulates. A long term study in a second rodent species is still an option. Dose selection has also been improved inasmuch as there are now several alternatives to the use of the maximum tolerated dose (MTD). In the past, the use of the MTD, when the normal homeostasis of the test animals is disturbed, has been considered one of the major problems with the rodent carcinogenicity bioassay. However, one of the alternative end-points to the use of the MTD, i.e. the comparison of plasma concentrations in rodents and humans, must be viewed with caution. While this may contribute to limiting the high dose level for agents of very low toxicity, the concept should not be interpreted as signifying that plasma concentrations provide a sound basis for comparing the carcinogenic activity of agents in different species. Recognition of the 4 properties (genotoxicity, immunosuppression, steroid hormonal activity and long term tissue damage), at least one of which is associated with each of the pharmaceuticals known to be carcinogenic to humans, should focus more attention on a search for these properties in patients. Absence of these properties at clinically relevant dose levels indicates that a pharmaceutical is highly unlikely to be carcinogenic to humans.     

Compliant Keeper system replication of the periodontal ligament protective damping function for implants: Part I

In 1987, Procter and Gamble Company (Cincinnati, Ohio) petitioned the US Food and Drug Administration (FDA) to amend the food additive regulations to allow sucrose esterified with fatty acids (olestra) to be used as a replacement for conventional fats. The petitioner later restricted its request for use in savory snacks. FDA considered evidence submitted by the petitioner, the opinions of experts, proceedings from the FDA Food Advisory Committee, and public discussion and concluded on January 25, 1996, that olestra was safe for use in savory snacks (eg, salty snacks such as potato chips, corn chips). Olestra is not toxic, carcinogenic, genotoxic, or teratogenic and is neither absorbed nor metabolized by the body, but may be associated with gastrointestinal tract symptoms such as cramping or loose stools. In addition, olestra affects the absorption of fat-soluble vitamins but does not affect the absorption of water-soluble nutrients. The petitioner's studies concluded that when olestra was consumed with foods containing vitamins A, D, E, or K, the fat substitute could have an effect on the absorption of these nutrients. Therefore, FDA is requiring that fat-soluble vitamins lost through absorption be added back to olestra as follows: 170 IU vitamin A per gram olestra, 12 IU vitamin D per gram olestra, 2.8 IU vitamin E per gram olestra, and 8 micrograms vitamin K per gram olestra. As part of the conditions of approval FDA is requiring that the food labels of products containing olestra disclose the vitamin compensation and the potential gastrointestinal effects. FDA is also requiring that further studies examining consumption patterns and the effects of olestra on human beings be conducted.     

Role of food interaction pharmacokinetic studies in drug development. Food interaction studies of theophylline and nifedipine retard and buspirone tablets

Due to several mechanism, meals may modify the pharmacokinetics of drug products, thereby eliciting to clinically significant food interaction. Food interactions with the drug substance and with the drug formulation should be distinguished. Food interaction of different drug products containing the same active ingredient can be various depending on the pharmaceutical formulation technology. Particularly, in the case of modified release products, the food/formulation interaction can play an important role in the development of food interaction. Well known example, that bioavailability of theophylline can be influenced in different way (either increased, decreased or unchanged) by concomitant intake of food in the case of different sustained release products. The role and methods of food interaction studies in the different kinds of drug development (new chemical entity, modified release products, generics) are reviewed. Prediction of food effect response on the basis of the physicochemical and pharmacokinetic characteristics of the drug molecule or formulations is discussed. The results of three food interaction studies carried out the products of EGIS Pharmaceuticals Ltd. are also reviewed. The pharmacokinetic parameters of theophyllin 400 mg retard tablet were practically the same in both fasting condition and administration after consumption of a high fat containing standard breakfast. The ingestion of a high fat containing breakfast, increased the AUC of nifedipine from 259.0 +/- 101.2 ng h/ml to 326.7 +/- 122.5 ng h/ml and Cmax from 34.5 +/- 15.9 ng/ml to 74.3 +/- 23.9 ng/ml in case of nifedipine 20 mg retard tablet, in agreement with the data of literature. The statistical evaluation indicated significant differences between the pharmacokinetic parameters in the case of two administrations (before and after meal). The effect of a high fat containing breakfast for a generic version of buspiron 10 mg tablet and the bioequivalence after food consumption were studied in a single-dose, three-way (test and reference products administered after consumption of standard breakfast, as well as test product in fasting condition), cross-over, food effect bioequivalence study. According to the results, the test product--which, in a former study proved to be bioequivalent with the reference product in fasting state--is bioequivalent with the reference product under feeding conditions and the food intake influenced the pharmacokinetics of the test tablets.     

Conceptual and statistical issues in the validation of analytic dilution assays for pharmaceutical applications

The discovery, research, and development of a pharmaceutical product relies on the availability of validated assays for assessing product characteristics and drug effects in vivo and in vitro. Development of a validated assay is a multifaceted activity that provides many interesting challenges for bioanalytical chemists and statisticians. In this paper, the similarity condition for fundamental validity of an analytic dilution assay is reviewed as a basic concept underlying the validation of assays for pharmaceutical applications. The distinction between the validity and the acceptability of an assay is considered in terms of the characteristics evaluated during four stages of validation. Recent guidelines on the validation of analytical procedures published by the U.S. Food and Drug Administration are appraised from a statistical perspective, and statistical issues in the validation process are discussed.     

New therapeutic agents marketed in 1993

In 1993, the Food and Drug Administration (FDA) approved 25 new molecular entities (NMEs), 23 of which are for therapeutic use and two are diagnostic agents. Eleven of the NMEs for therapeutic use, as well a new biological agent intended for therapeutic use, were both approved and marketed in the United States in 1993. In addition, 11 other NMEs that the FDA approved before 1993 (most in late 1992) were marketed during the year. Thus, a total of 23 therapeutic agents reached the U.S. market for the first time in 1993, a considerably lower number than the 30 new therapeutic agents marketed in 1992 and the record number 31 new agents marketed in 1991. Many of the 13 therapeutic agents approved in 1993 but not marketed before the end of the year have become available in early 1994. This review of the therapeutic agents first marketed in 1993 considers their most important properties and, when possible, compares them with other available agents with similar properties. Of the 23 new therapeutic agents, 22 are considered in this paper. The one agent not reviewed is flosequinan, which was withdrawn from the market after being available only several months because of a concern about toxicity. This discussion of new drugs focuses on the most important properties of these agents; when additional information is needed, more comprehensive references and the product literature should be consulted.     

Risk assessment of butadiene in ambient air; the approach used in the UK

The UK Committee on Carcinogenicity of Chemicals in Food, Consumer Products and the Environment (COC) and the related Committee on Mutagenicity provided advice on 1,3-butadiene in 1992. This followed detailed consideration of the available mutagenicity, animal carcinogenicity and epidemiology data plus information on toxicokinetics. They concluded that 1,3-butadiene was an in vivo mutagen, a potent genotoxic animal carcinogen and should be regarded as a probable human carcinogen. The Department of Health is not aware of more recent data warranting reconsideration of these conclusions. General advice on setting air quality standards for carcinogenic air pollutants was given by the COC. Although the prudent assumption of the absence of any safe level for genotoxic carcinogens was preferred, a pragmatic approach based essentially on assessment of the exposure at which no increased risk would be detected, plus a safety factor, was considered reasonable for compounds like butadiene where exposure cannot be totally avoided. This approach, plus recognition that it is unadvisable to allow ambient levels of genotoxic carcinogens to rise, is used in the UK. The procedure by which the Department of Environment's Expert Panel on Air Quality Standards recommended a value of 1 ppb for butadiene based on these principles is described.     

Prevention of 2-acetylaminofluorene-induced extrahepatic short-term effects by 3-methylcholanthrene

It is well known that simultaneous application of polycyclic carcinogenic hydrocarbons, especially 3-methylcholanthrene (MC) inhibits or prevents tumorigenesis induced by carcinogenic aromatic amines or azo dyes. Short-term tests showed a mitogenic effect upon adrenal cortex 48 hours following a single dose of 2-acetylaminofluorene (AAF) among other carcinogenic substances. 6 mg/kg body weight given simultaneously prevent the proliferative response of the adrenals by AAF (60 mg/kg b.w.) in male Sprague-Dawley rats. These different effects can be assumed to depend on the production of carcinogenic derivatives or their non-production. Therefore, the positive adrenal reaction by other substances tested is probably also provoked by carcinogenic compounds. The lack of responsiveness by MC may reflect a fundamental change of AAF metabolism. The mode of action is unknown. Possible explanations are discussed.     

Localization using nonindividualized head-related transfer functions

The HPV proteins encoded by the early viral genes, including E6 and E7, are thought to subvert the normal regulatory pathways of infected cells to accommodate viral replication. Mechanistically some of this is accomplished by protein-protein interactions between viral proteins and a number of key cellular regulatory proteins that include tumor suppressor gene products. By undermining cellular regulatory pathways the HPV oncogenes cause hyperproliferation and the perturbation of normal cellular differentiation pathways. Although expression of the high-risk HPV-encoded E6 and E7 oncoproteins may be important prerequisites for cellular transformation, it is very likely that additional cellular changes are necessary for carcinogenic progression. The elucidation of the role of the early HPV genes in the initiation and/or maintenance of carcinogenic progression will continue to be a fascinating area of investigation and may reveal new opportunities for antiviral therapy and antitumor intervention.     

Dose-response studies and 'no-effect-levels' of N-nitroso compounds: some general aspects

One major problem in the evaluation of potential carcinogenic food additives and contaminants is that of thresholds or, better, of 'no-adverse-effect-levels'. Arguments in favor of the postulated 'irreversibility' of carcinogenic effects are based on dose-response studies, single dose and multigeneration experiments as well as on the concept of somatic mutation as the first step in carcinogenesis with subsequent transmittance of induced defects during cell replication. The problem of extrapolation of results of animal experiments using high doses to low exposure and low incidences in man is not yet solved satisfactorily. Possible practical consequences include zero tolerance, acceptable thresholds at low risk and safety factors. Acceptable intakes should never be considered constants but should be changeable as soon as new facts in regard to the safety evaluation are available.     

Gene transfer of herpes simplex virus type I thymidine kinase gene as a drug sensitivity gene into human lung cancer cell lines using retroviral vectors

A number of packaging materials are being used not only to contain food during distribution but also to serve as the cooking container. The higher temperatures that these materials reach led the US Food and Drug Administration (FDA) to issue an intent to publish new regulations in 1989. The food and packaging industries responded by conducting extensive research and submitting the results to FDA. The methods used and results obtained are discussed. Most of the data were focused on microwave susceptors and the volatile compounds generated. One project showed that for a specific product, popcorn, there was no transfer into the food. Work is continuing to validate methods to test for non-volatile compounds. In addition to susceptors, various paper and plastic materials are used in dual ovenable (microwave and conventional ovens) applications. Most of the research on these materials has investigated the food contact temperatures on testing for migrants. An update on the current regulatory status of packaging materials intended for high temperature use in the US is discussed.     

The volatile oil composition of fresh and air-dried buds of Cannabis sativa

We have modified the genome of the filamentous bacteriophage fd and also constructed a number of new vectors for the purpose of displaying peptides on the surface of the virion. These vectors facilitate the directional cloning of DNA encoding a peptide of interest at or near the N terminus of the major coat protein, the product of the bacteriophage gene VIII, and the construction of hybrid capsids in which the modified coat protein is interspersed with wild-type coat protein subunits.     

WWP, a new amino acid motif present in single or multiple copies in various proteins including dystrophin and the SH3-binding Yes-associated protein YAP65

A new repeating amino acid motif, which we called WWP, was found in several proteins of yeast, nematod or vertebrate origin. Among these are dystrophin, the product of the Duchenne muscular dystrophy locus, a protein (YAP65) which associates in vitro with the Src homology domain 3 (SH3) of the Yes proto-oncogene product, and a human putative GTPase-activating protein. As is the case for proteins which contain the SH2, SH3 and PH domains, at least some of the WWP-containing proteins appear to be signaling or cytoskeletal proteins, associated with plasma or organellar membranes, and specific protein-protein contacts are likely to be crucial to their function.