Recently, Valotis et al. 1 published a study on human receptor kinetics, tissue binding affinity, and stability of mometasone furoate. They reported some novel and insightful data on human receptor kinetics demonstrating fast and extensive association to the human glucocorticoid receptor with dissociation of the mometasone furoate receptor complex faster than fluticasone propionate. This is an important finding as the tissue affinity of inhaled mometasone furoate and the redistribution from lung tissue into systemic circulation is a determinant of pharmacological action.
However, Valotis et al. 1 reported ''there has been no information about the stability of mometasone furoate in human lung tissue or human plasma.'' The authors state ''so far, there has been no published data on the stability of mometasone furoate in the therapeutic target tissue, for example, human lung.'' Furthermore, it is not clear yet which degradation products are formed in human plasma. Valotis et al. 1 give reference to some of our published work. [2][3][4] In these studies, we detected and published the presence of four degradation products of mometasone furoate in human plasma in a validated HPLC method. 2 Valotis et al. 1 developed an alternative and more sensitive method of HPLC analysis, however, no