Limited sampling strategy

The difficulty in determining dose delivered with oral administration of high-dose busulfan in preparative regimens for hematopoietic stem cell transplantation results in lethal toxicity due to overdosing and increased potential for relapse with recurrent disease. Oral pharmacokinetic studies ineffectively determine proper AUC for reliable establishment for a proper therapeutic dose. Studies with IV formulations have demonstrated that all patients are evaluable. With the development of a limited sampling strategy to analyze proper AUC over intermittent time periods, improved patient risk profiles for busulfan have been implemented in clinical practice. 

Vaughan WP, Carey D, Perry S, Westfall AO, and Salzman DE (2002) A limited sampling strategy for pharmoco-... 

Ma JD. Nafziger AN, Kashuba AD. et al. Limited sampling strategy of S-warfarin concentrations. but not warfarin S/R ratios, accurately predicts S-warfarin AUC during baseline and inhibition in CYP2C9 extensive metabolizers. J Clin Pharmacol 2004 44(6) 570-6. 

L. Nguyen, B. Tranchand, C. Pnozzo, and P. Variol, Population pharmacokinetics model and limited sampling strategy for intravenous vinorelbine derived from phase I clinical trials. Br J Clin Pharmacol 53 459-468 (2002). 

Of particular interest is the utility of population modeling when sampling is limited, as is often the case in pediatric studies. For example, etoposide toxicity and efficacy have been related to exposure. It was not reasonable to execute an intense sampling PK study in the pediatric population, therefore a limited sampling strategy was proposed and done. In each subject only two samples were collected—one at about 3 hours postdose and another 5.5 hours postdose. The approach was shown to be able to estimate PK parameters that had little bias (18). 

Moore, M.J., Bunting, P., Yuan, S., and Theissen, J.J. Development and validation of a limited sampling strategy for 5-fluorouracil given by bolus intravenous administration. Therapeutic Drug Monitoring 1993 15 394-399. 

Cheung CY et al (2008) Dried blood spot measurement application in tacrolimus monitoring using limited sampling strategy and abbreviated AUC estimation. Transpl Int 21 140-145... 

Measurement Method Selection. A measurement method should meet sampling strategy requirements to the degree that the data can be used for decision making. This does not mean that it must be the optimum method with respect to all requirements. The range of methods available is limited and it is often necessary to select a method deficient in one or more attributes but which can yield data from which conclusions can be drawn with the desired degree of confidence. Some of the attributes to be considered in selecting a method foUow. 

It is obvious that such an assessment is formidable, technically difficult, and extremely expensive. Since an environmental source assessment study is required to characterize the total pollution potential of all waste streams, the sampling program must be more extensive than those conducted for the acquisition of process or control engineering data. Assessment sampling is more complete in that all waste streams are sampled and no attempt is made to limit sampling to a preselected number of process streams. The sampling is also more comprehensive in that all substances of potential environmental concern must be detectable above some minimum level of concern. These requiements of completeness and comprehensiveness call for a strategy of approach in which the philosophy and structure ensure maximum utilization of available resources. 

Given the quite simple and clear model of sampling strategies and the economically very important impact of sampling there has been published comparatively little about sampling strategies. The emphasis has been more on analytical techniques. Detection limit, precision and capacity have been the main topics in analytical chemistry for more then 30 years. Chemometrics, providing means to extract more informa-... 

A very important theorem in statistics, the central limit theorem, states that as sample size increases, the distribution of a series of means from any frequency distribution will become normally distributed. This fact can be used to devise an experimental or sampling strategy that ensures that data are normally distributed, i.e. using means of samples as if they were primary data. 

If lower limits would not have detected the shift, then evaluate the cause of the failure, and develop a new sampling strategy for the key step(s) where failure occurred. Institute the CAP and verify that corrective actions taken were effective in improving product quality. 

The large number of contemporary MC approaches for dealing with the problem of phase behaviour can usefully be categorized in terms of the the interphase path they utilize to connect the phases and the sampling strategy adopted to traverse this path. We have exemplified some of the principal concepts within the limited context of the phase behaviour of simple particle... 

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