Pharmacokinetic considerations in zinc supplementation: getting the dose right

Studies on the efficacy of zinc supplementation in populations at risk for zinc deficiency are hampered by the lack of information on the proper dose and timing of such doses. These problems arise in part from the lack of adequate information derived from pharmacokinetic (PK) studies, the usual source of such data for supplementation with drugs. Because endogenous zinc pools exist in tissues, standard PK studies provide inaccurate answers, and isotopic tracer studies in healthy subjects must be used to develop models of zinc kinetics. But these studies poorly estimate dose and timing of doses, and the results cannot be used to inform dosing in the zinc deficient patient. Thus, treatment of zinc deficiency in high risk populations has been empirical, and will continue to be so, until more reliable information on the kinetics of zinc supplementation are available.