Influence of ascites on tobramycin pharmacokinetics

The influence of ascites on the disposition of tobramycin was examined in eight subjects with cirrhosis of the liver. Five of these subjects had resolution of ascites so they could be used as their own controls. While there was no significant effect of ascites on the clearance and half-life of tobramycin, the volume of distribution of tobramycin was significantly larger when ascites was present, 0.32 versus 0.26 liter/kg (P less than 0.01). There was a trend for the volume of distribution to be larger in those patients with larger ascitic fluid volume.