Excipients are essential components of drug products. They are also potential toxicants. Examples of known excipient-induced toxicities include renal failure and death from diethylene glycol, osmotic diarrhea caused by ingested mannitol, hypersensitivity reactions from lanolin, and cardiotoxicity induced by propylene glycol. Proposals to test or market new drug products in the United States should adequately address the safety of the proposed exposure to the excipients in those products. The specific safety data that may be needed will vary depending upon the clinical situation, including such factors as the duration, level, and route of exposure, but may include acute, repeat-dose, reproductive, and genetic toxicity data, carcinogenicity data, and specialized toxicology information, such as sensitization or local irritation data. Many guidances exist to aid in the development of pharmaceuticals, including the International Conference on Harmonization (ICH) documents and various Food and Drug Administration/Center for Drug Evaluation and Research (FDA/CDER) pharmacology and toxicology guidances. The FDA/CDER has recently adopted a new guidance for industry, "Nonclinical Studies for Development of Pharmaceutical Excipients," which focuses on issues associated with development of safety databases that will support clinical use of excipients in drug products. The new guidance document is introduced and discussed in this article.

Solar ultraviolet radiation (UVR) is recognized as a major cause of non-melanoma skin cancer in man. Skin cancer occurs most frequently in the most heavily exposed areas and correlates with degree of outdoor exposure. The incidence of skin cancer is also increased by contact with photosensitizing drugs and chemicals such as psoralens, coal tars and petroleum stocks. Other substances which do not act as photosensitizers, such as immunosuppressants taken by organ transplant recipients, also increase the risk of skin cancer. The U.S. Food and Drug Administration requests, on a case-by-case basis, that risk of enhanced photocarcinogenesis is assessed for many classes of drugs. Health Canada's Therapeutic Products Programme has issued a Notice of Intent to regulate pharmaceutical products which may enhance carcinogenicity of the skin induced by ultraviolet radiation. Other national regulatory agencies review such data when they exist, but their own requirements emphasize batteries of short-term in vitro and in vivo tests. While they may support drug development strategies, short-term tests have yet to be validated as predictors of the ability of drugs or chemicals to enhance photocarcinogenesis. Published protocols now describe study designs and procedures capable of determining whether test agents enhance the rate of formation of UVR-induced skin tumors.

Toxicological studies constitute an essential part of the effort in developing a botanical supplement into a drug product. The US Food and Drug Administration recently published a draft guidance and established a special botanical review team to assist academic and industry sponsors to manage this and other regulatory considerations related to this unique group of drug products. In this article, the current state of regulatory viewpoints on issues related to requirements and recommendations of various types of nonclinical toxicity studies in support of advanced phases clinical trials and filing a New Drug Application of a botanical are discussed. Topics include nonclinical pharmacology/toxicology view of previous human experience and initial clinical trial, regulatory perspectives on acute toxicity studies, chronic toxicity studies, mutagenicity studies, reproductive toxicity studies, and carcinogenicity studies on botanicals. Certain regulatory review-related issues are also presented. It is anticipated that through a proactive 2-way communication between the Agency and the sponsor, toxicological development of botanical drug product can be significantly facilitated.

Clinical Pharmacology & Therapeutics (1996) 59, 265–267; doi: