Special study designs

Additionally, there are specialized studies designed to address endpoints of concern for almost all drugs (carcinogenicity, reproductive or developmental toxicity) or concerns specific to a compound or family of compounds (local irritation, neurotoxicity, or immunotoxicity, for example). When these are done, timing also requires careful consideration. It must always be kept in mind that the intention is to ensure the safety of people in whom the drug is to be evaluated (clinical trials) or used therapeutically. An understanding of special concerns for both populations should be considered essential. 

Temple, R.J. (1994) Special study designs early escape, enrichment, studies in nonresponders. Commun Statist Theory Meth 23 499-531. 

Knowledge of critical periods may be helpful in determining the plausibility that adverse effects were produced by chemical exposure. If exposures occur only after the critical period for a structure, then abnormalities in that organ are unlikely to be attributable to the exposure. Such determinations require special study designs in which exposures are limited to only a fraction of development. 

Reproductive toxicity studies. Although the study protocols so far described may give information on the effect (or lack of it) that a solvent may have on both male and female organs of reproduction, they do not give any information on the effect of exposure on the ability of the animals to reproduce normally. In order to obtain such information, special study designs are necessary, and protocols have been developed to permit the study of ... 

Plackett and Burman [1946] have developed a special fractional design which is widely applied in analytical optimization. By means of N runs up to m = N — 1 variables (where some of them may be dummy variables which can help to estimate the experimental error) can be studied under the following prerequisites and rules ... 

The underlying principle is that subjects should only participate in a clinical trial if they agree to do so after they have fully understood the trial and its implications. In all studies, informed consent must be obtained from the subject or, where special situations occur, from his or her representative. How this is achieved depends on the study design, procedure and the country where the study is being conducted. Typically, it requires a... 

The official estimate in 1998 also includes a breakdown by race (table 9.8) Note that Hispanic is a special ethnic designation, and can be of any race. America is becoming less white, as most racial minorities are experiencing population increases faster than the whites. There is also the rise of the multi-racial population in America, which will be included in future population classifications as a separate category. All these characteristics and changes in the population are important, as marketers need to study the consumption preferences of each segment of the population. 

As mentioned above, special studies such as range-finding studies are typically conducted during the development process. These ranging studies establish the limits for the critical parameters [4], A statistical tool called design of experiments [5] DOE or factorial design) is invaluable during such studies. 

In the reference-range approach, reference ranges (or intervals),1 are established, and biomonitoring values from individuals or subgroups are compared with them. The validity and utility of biomonitoring values for use as reference ranges depends on study design and data quality, with special attention to the availability and comparability of data on the reference population in relation to the study population. 

An important property of design of experiments is a search for increased accuracy in fixing a factor and measuring an error. The researcher must be able to determine and estimate a measurement error correctly. Measurements and measurement errors are a subject of special study, see [7, 8]. 

All these studies should be performed in compliance with good laboratory practice (GLP) where feasible. The screening battery is frequently performed with full GLR More complex or specialized studies should be well-designed, properly controlled, and carefully documented when not in compliance. When safety pharmacology endpoints are incorporated into toxicology studies, not an uncommon situation, they should be conducted under GLP. 

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