Coadministration has not been studied but based on metabolism and clearance a clinically significant interaction is unlikely. Bismuth subsalicylate is largely hydrolysed in the stomach to form salicylic acid, which is rapidly absorbed, and insoluble bismuth salts, which are excreted unchanged in faeces. Ritonavir is metabolized by CYP3A4. Bismuth subsalicylate is unlikely to affect CYP3A4.