Evolution of clinical trials for irritable bowel syndrome: issues in end points and study design.

Irritable bowel syndrome (IBS) involves a broad range of physiological and psychological alterations that may affect brain-gut dysregulation, gut function, visceral perception, and mucosal integrity and function. Despite advances in our understanding of basic neuroenteric mechanisms and the role of effectors and transmitters in the brain-gut axis, a reliable biologic marker of IBS has yet to be identified. IBS diagnosis and status depend entirely on an assessment of IBS signs and symptoms. This has made development of optimal end points and study design for evaluation of efficacy of IBS drugs a challenge. This article addresses three main topics: the evolution of primary end points for IBS clinical trials; a potential path forward for IBS end points in new clinical trials; and recommendations for the future development of patient-reported outcome (PRO) instruments for use in IBS clinical trials.

Patient-reported outcomes supporting anticancer product approvals.

In 2006, the US Food and Drug Administration (FDA) published draft guidance to provide recommendations for development, validation, implementation, and interpretation of patient-reported outcome (PRO) measures that can support treatment benefit claims in product labeling. Here, we summarize and discuss FDA approvals of anticancer products in the context of the draft guidance. We identified anticancer product approvals having efficacy claim(s) based at least in part on a PRO. In addition, we collated limitations of PRO instruments commonly submitted for regulatory review over the period from October 1, 2004 to September 30, 2006. From 1995 onward, nine indications were approved for seven anticancer products based at least in part on a PRO. In eight of nine approvals, PRO data supplemented other evidence of clinical benefit. In seven approvals, the PRO measured a single symptom or functional domain that was directly attributable to the treatment benefit observed in the disease. The FDA's draft PRO guidance describes principles that have been used in anticancer product approvals for more than a decade. PRO end points typically support treatment benefit claims that refer to a patient's symptoms or ability to function. Single-item PROs may be acceptable. PRO data should be both internally consistent and aligned with other evidence of clinical benefit. The FDA encourages sponsors to consult with the FDA early in the process of PRO development.

Patient-reported outcomes to support medical product labeling claims: FDA perspective.

This article concerns development and use of patient-reported outcomes (PROs) in clinical trials to evaluate medical products. A PRO is any report coming directly from patients, without interpretation by physicians or others, about how they function or feel in relation to a health condition and its therapy. PRO instruments are used to measure these patient reports. PROs provide a unique perspective on medical therapy, because some effects of a health condition and its therapy are known only to patients. Properly developed and evaluated PRO instruments also have the potential to provide more sensitive and specific measurements of the effects of medical therapies, thereby increasing the efficiency of clinical trials that attempt to measure the meaningful treatment benefits of those therapies. Poorly developed and evaluated instruments may provide misleading conclusions or data that cannot be used to support product labeling claims. We review selected major challenges from Food and Drug Administration's perspective in using PRO instruments, measures, and end points to support treatment benefit claims in product labeling. These challenges highlight the need for sponsors to formulate desired labeling claim(s) prospectively, to acquire and document information needed to support these claim(s), and to identify existing instruments or develop new and more appropriate PRO instruments for evaluating treatment benefit in the defined population in which they will seek claims.

Challenges to use of health-related quality of life for Food and Drug Administration approval of anticancer products.

The U.S. Food and Drug Administration (FDA) approves labeling claims of drug efficacy based on substantial evidence of clinical benefit demonstrated in adequate and well-controlled investigations. Patient-reported outcomes (PROs) may support marketing claims of clinical benefit, either alone or with other study endpoints. Health-related quality of life (HRQL) is a PRO that comprehensively measures patients' reported health status. We present an overview of why HRQL-based efficacy claims have not to date been accepted by the FDA for inclusion in anticancer product labels. Persistent challenges to allowance of such claims include shortcomings in randomization and blinding of clinical trials, missing data, statistical multiplicity, and unclear intrinsic meaning of selected HRQL findings.

Risk minimization practices for pregnancy prevention: understanding risk, selecting tools.

According to the March of Dimes, approximately 4% (1/28) of babies are born in the US each year with a birth defect. For the majority of birth defects the etiology is unknown, although chemicals, including drug exposures, probably account for less than 1% of all birth defects. The identification of potential human teratogenicity during drug development is important because drug-induced adverse fetal effects are potentially preventable with the application of risk assessment strategies and risk minimization tools and programs to minimize risk of pregnancy exposure while preserving access to drug benefits; risk assessment and risk minimization together comprise risk management. It is important that risk minimization programs intended to limit fetal exposure use a consistent approach and are tailored to the product-specific risk concerns in order to optimize the benefit-risk balance for a particular drug. This paper highlights general considerations in developing specific risk minimization programs to prevent fetal drug exposure including the relative advantages and disadvantages of each strategy.

Antibiotic use in pregnancy and lactation: what is and is not known about teratogenic and toxic risks.

OBJECTIVE: Over ten million women are either pregnant or lactating in the United States at any time. The risks of medication use for these women are unique. In addition to normal physiologic changes that alter the pharmacokinetics of drugs, there is the concern of possible teratogenic and toxic effects on the developing fetus and newborn. This article reviews the risks and pharmacokinetic considerations for 11 broad-spectrum antibiotics that can be used to treat routine and life-threatening infections during pregnancy and lactation. DATA SOURCES: Information from the U.S. Food and Drug Administration (FDA) product labels, the Teratogen Information Service, REPROTOX, Shepard's Catalog of Teratogenic Agents, Clinical Pharmacology, and the peer-reviewed medical literature was reviewed concerning the use of 11 antibiotics in pregnant and lactating women. The PubMed search engine was used with the search terms "[antibiotic name] and pregnancy," "[antibiotic name] and lactation," and "[antibiotic name] and breastfeeding" from January 1940 to November 2005, as well as standard reference tracing. METHODS OF STUDY SELECTION: One hundred twenty-four references had sufficient information concerning numbers of subjects, methods, and findings to be included. TABULATION, INTEGRATION, AND RESULTS: The teratogenic potential in humans ranged from "none" (penicillin G and VK) to "unlikely" (amoxicillin, chloramphenicol, ciprofloxacin, doxycycline, levofloxacin, and rifampin) to "undetermined" (clindamycin, gentamicin, and vancomycin). Assessments were based on "good data" (penicillin G and VK), "fair data" (amoxicillin, chloramphenicol, ciprofloxacin, doxycycline, levofloxacin, and rifampin), "limited data" (clindamycin and gentamicin), and "very limited data" (vancomycin). Significant pharmacokinetic changes occurred during pregnancy for the penicillins, fluoroquinolones and gentamicin, indicating that dosage adjustments for these drugs may be necessary. With the exception of chloramphenicol, all of these antibiotics are considered compatible with breastfeeding. CONCLUSION: Health care professionals should consider the teratogenic and toxic risk profiles of antibiotics to assist in making prescribing decisions for pregnant and lactating women. These may become especially important if anti-infective countermeasures are required to protect the health, safety, and survival of individuals exposed to pathogenic bacteriologic agents that may occur from bioterrorist acts.

Pregnancy exposure registries.

Scientifically valid data on the safety of drug use during pregnancy are a significant public health need. Data are rarely available on the fetal effects of in utero exposure in human pregnancies, particularly when a drug is first marketed. Data from animal reproductive toxicology studies, which function as a screen for potential human teratogenicity, are usually all that is available in a product's labelling. For practising clinicians, translating known animal risks into an accurate assessment of teratogenic risks in their patients is very difficult, if not impossible. Without human data on the effects of in utero drug exposure, it is difficult for physicians and other healthcare providers (e.g. genetic counsellors) to adequately counsel patients about fetal risks. Therefore, a pregnant woman may decide to unnecessarily terminate a wanted pregnancy or forego needed drug therapy. In spite of the lack of data on the safety of drug use during human pregnancies, pregnant women are exposed to drugs either as prescribed therapy or inadvertently before pregnancy is known (over one-half of pregnancies are unplanned). Because little is known about the teratogenic potential of a drug in humans before marketing, post-marketing surveillance of drug use in pregnancy is critical to the detection of drug-induced fetal effects. The existing passive mechanism of spontaneous reporting of adverse drug effects is inadequate to routinely detect drug-induced fetal risks or lack of such risks. Therefore, post-marketing pregnancy exposure registries are being increasingly used to proactively monitor for major fetal effects and to describe margins of safety associated with drug exposure during pregnancy. However, differing methodological rigour has been applied to the development of pregnancy exposure registries. It is important that all pregnancy registries develop epidemiologically sound written study protocols a priori. It is only through the use of rigorous methodology and procedures that data from pregnancy exposure registries will withstand scientific scrutiny. Successful recruitment of an adequate number of exposed pregnancies, aggressive follow-up, and complete and accurate ascertainment of pregnancy outcome are critical attributes of a well-designed registry.

Risk management strategies in the Physicians' Desk Reference product labels for pregnancy category X drugs.

BACKGROUND: Drugs that carry a concern for teratogenicity are often classified as pregnancy category X in the drug label and contraindicated for use during pregnancy. Many drug labels can be found in the Physicians' Desk Reference (PDR), a widely used source of drug information by American clinicians and patients. OBJECTIVE: To review product labelling in the electronic PDR for the pregnancy category X products for pregnancy prevention risk management components in labelling. METHODS: The electronic version of the 2001 and 2002 PDR was searched for 'pregnancy category X' products using the full text search feature. All product labels identified were retrieved and reviewed for trade name, generic name, manufacturer and indication. Product labels were manually searched for any pregnancy prevention risk management strategies included in labelling. Those labels that had specific pregnancy prevention risk management strategies were further evaluated. RESULTS: One hundred and seventeen pregnancy category X products were obtained from 2249 products searched in the 2001 PDR database and 124 pregnancy category X products were obtained from the 2150 products in the 2002 PDR database. All pregnancy category X products identified were drug products. The label/package insert for each drug was reviewed to identify risk management strategies for pregnancy prevention. The majority of the labels include as the sole risk management strategy either a black box warning and/or a contraindication for use in women who are or may become pregnant. Only 13 drugs contained specific pregnancy prevention risk management strategies in the label directing the clinician and/or patient, e.g. frequency of pregnancy testing, number and type of contraception methods. Two drugs, bexarotene capsules and gel, were only included in the 2001 PDR. Three drugs, isotretinoin, acitretin, and thalidomide, have formal pregnancy prevention risk management programmes. CONCLUSION: This study demonstrates the varied risk management approaches in labelling for pregnancy prevention for pregnancy category X drugs. There is a need for consistency in the classification of pregnancy category X products and the pregnancy prevention risk management strategies utilised in the labelling for them.