Nafcillin is considered therapeutically equivalent to oxacillin, although one retrospective study found greater rates of hypokalemia and acute kidney injury in patients taking nafcillin compared to patients taking oxacillin.
There is evidence that it induces cytochrome P-450 enzymes specifically CYP2C9. Several drugs with a narrow therapeutic window, such as warfarin and nifedipine, are metabolized by CYP2C9.
Nafcillin contains salts added as stability media. These added salts could cause edema or fluid accumulation. It would be prudent to avoid this medication if there were a concern for a congestive heart failure or kidney disease.
^Pham P, Bartlett JG (January 2, 2009). "Nafcillin". Point-of-Care Information Technology ABX Guide. Johns Hopkins University. Retrieved on July 10, 2009. Freely available with registration.
^Bonow RO, Carabello BA, Kanu C, et al. (August 2006). "ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (writing committee to revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease): developed in collaboration with the Society of Cardiovascular Anesthesiologists: endorsed by the Society for Cardiovascular Angiography and Interventions and the Society of Thoracic Surgeons". Circulation. 114 (5): e84–231. doi:10.1161/CIRCULATIONAHA.106.176857. PMID16880336.