Meds to protect Kidneys prior to heart cath

My husband is having a second heart cath performed. Due to the contrast harming his kidneys during his first cath, they're giving him some prophlactic medicine. What are the meds used prior to heart caths to prevent damage to kidneys? We were wondering if there were several or only one meds that would do this and how are they administered?

[Cleveland Clinic]

Orally there is mucomyst, which acts as a free oxygen radical scavenger  and prior to the  left heart catheterization intra venous sodium bicarbonate. Make sure they use the iso-osmolar contrast agent to minimize the volume shifts and that they use as little contrast as possible.