Quantitation of a Topically Dosed Pharmaceutical in Skin Tissue by MALDI-MS Imaging
During drug development studies it is important to determine whether the compound of interest is reaching its desired target as well as how much of the compound is present. Traditional LCMS methods allow for absolute quantitation within bulk tissue homogenates, but spatial information is lost. Quantitative whole body autoradiography preserves the spatial information, but lacks the chemical specificity to differentiate parent drug from metabolites and also requires that an expensive radiolabeled version of the drug be synthesized. Mass spectrometry imaging (MSI) alleviates these shortcomings.
The molecular specificity of mass spectrometry allows for:
Facile differentiation of drug and metabolite
Spatial localization due to tissue sections being kept intact
Quantitation based on the use of a stable isotope labeled internal standard
Simultaneous detection of endogenous molecules that may be affected by pharmaceutical dosing