In patients with renal insufficiency roxithromycin pharmacokinetic parameters are significantly altered. In particular, the Cmax, the AUC and the T1/2 are increased and the Clr is reduced. In alcoholic cirrhotic patients the blood half-life is dosage higher than in normals. In spite of this, in these types of patients the usual roxithromycin dosage should not be modified. Potential pharmacokinetic drug interactions that involve roxithromycin are very few and concern only disopyramide and theophylline. Theophylline concentrations should be monitored if the pretreatment blood level is greater than 15 mg/l.