Estudo da dose excipiente: fármaco com avalia？？o da hiperplasia neointimal por tomografia de coerência óptica e histopatologia em artérias coronárias porcinas após o emprego do bal？o eluidor de sirolimus

background: magic touchtm is a sirolimus based nano carrier balloon. we aimed at finding the excipient:drug ratio with the highest capacity to inhibit neointimal proliferation 28 days after the use of this balloon after bare metal stenting in porcine coronary arteries. methods: fourteen domestic pigs with coronary bare metal stenting followed by dilation (60 seconds) using balloons with an excipient:sirolimus ratio of 1:1, 0.5:1, 0.25:1, 1:0 or a control balloon were evaluated. after 28 days neointimal hyperplasia was assessed by optical coherence tomography and histopathology. results: percent neointimal hyperplasia (%) assessed by optical coherence tomography and histomorphometry was 32.2 and 35.1, 28.1 and 33.4, 17.3 and 20.9, 28.6 and 30.2, and 37.9 and 42.3 in the groups with 0.25:1, 0.5:1, 1:1, 1:0 excipient:sirolimus ratios and control balloon, respectively (p = 0.03 for excipient:sirolimus 1:1 versus control balloon). the neointimal interstrut thickness (mm) was 0.23, 0.30, 0.16, 0.24 and 0.30 in the groups with 0.25:1, 0.5:1, 1:1, 1:0 excipient:sirolimus ratios and control balloon, respectively (p < 0.01 for excipient:sirolimus 1:1 versus control balloon). the scores of inflammation, injury and fibrin deposition were low and there was no significant difference among groups. conclusions: there was a stepwise increase in inhibitory efficacy of neointimal proliferation as the excipient concentration increased; the lowest efficacy was observed with the 0.25:1 excipient:sirolimus formulation and the most intensive inhibition was observed with the 1:1 excipient:sirolimus formulation. the 1:1 excipient:sirolimus formulation significantly reduced neointimal proliferation when compared to the control group, with low inflammation and injury scores.