Table 1.

Severity rating of the interactions between drugs indicated for renal dysfunction and co-administered drugs

Rating	Designation	Action	Explanation
A	Unknown	No known interaction	Unknown
B	Minor	No action needed	The interaction would have limited clinical effects. May include an increase in the frequency or severity of the side effects but generally would not require a major alteration in therapy
C	Moderate	Monitor therapy	The interaction may result to exacerbation of the patient’s condition and/or require an alteration in therapy
D	Major	Therapy modification	The interaction may be life threatening and/or require medical serious adverse events
X	Contraindicated	Avoid combination	The drugs are contraindicated for concurrent use

A and B are considered nonclinically significant drug interactions, whereas C, D, and X are considered clinically significant drug interactions