The potential use of markers in drug development

There are at least three recurring questions crucial to the drug and drug formulation development processes that could be addressed by marker methodology: (1) Is the assessment of an effective dose or dose regimen correct? (2) Is an inadequate response or nonresponse secondary to pharmacology or to inadequate compliance? (3) Can various formulations provide significantly better therapy for certain populations? Characteristics of an ideal marker system would include: Simple and reliable to measure. Able to yield reliable evaluation of routine adherence in single or multiple dose situations. Biologically inert. Samples for measurement can be obtained unobtrusively. Samples are painless to obtain (for patient and clinic staff). Absorption and kinetic characteristics approximate those of the therapeutic candidate. Able to be presented in multiple formulations. Current methodology for addressing these questions is far short of ideal. Therefore, if marker methodology that lacks the limitation of present technology could be developed, it potentially would find wide use during the drug development process.