Reverse Engineering I

Can you figure out from the treatment what the disease is?

A 20 year old on a liver transplant list is taking the drug above. His parents remind him to take the drug on an empty stomach since absorption can be decreased by as much as 50% if taken with food. He takes 1000mg daily in divided doses. When he first started the medication, a lot of caution was taken because of his penicillin allergy. Luckily, he didn't get early sensitivity reactions which are usually characterized by fever, cutaneous eruptions, lymphadenopathy, neutropenia, and thrombocytopenia. He has had some proteinuria, but luckily, his kidney function has remained stable since the drug is renally metabolized. He gets routine blood counts to monitor for aplastic anemia. He gets 24 hour urine collections with his hepatologist to make sure he is compliant with treatment. His child neurologist and ophthalmologist are optimistic that he will get a liver transplant.

Challenge: What's the drug and what's the disease?

Image is in the public domain.