 Several studies have been published in recent years using DBS sampling method, for various drugs such as antimalarials, antiepileptics, antiretrovirals, metformin, benzodiazepines, or immunosuppressants. Only one clinical validation study of TDM of CsA using DBS method was published by Wilhelm et al. 2013 in a population of 38 patients who received allogeneic stem cell transplant recipients. The results showed excellent correlation between the concentrations determined by the two sampling methods. 