From the FDA Drug Label
Conditions such as renal impairment (creatinine clearance under 60 mL per minute or clinically significant elevated serum creatinine) The patient has a creatinine clearance of 64, which is above the threshold of 60 mL per minute. Therefore, Macrobid (nitrofurantoin) can be used in this patient, as their renal function is not significantly impaired according to the provided threshold 1.
From the Research
Nitrofurantoin (Macrobid) can be used with caution in patients with a creatinine clearance of 64 mL/min, as this is above the recommended threshold for safe use. For patients with a creatinine clearance of 30-60 mL/min, close monitoring is advised, but the medication can generally be prescribed at standard dosing (typically 100 mg twice daily for 5-7 days for uncomplicated urinary tract infections) 2. Nitrofurantoin should be avoided when creatinine clearance falls below 30 mL/min because the drug won't adequately concentrate in the urine to be effective, and there's increased risk of toxicity, particularly peripheral neuropathy and pulmonary reactions.
Key Considerations
- The concern with reduced renal function is twofold: decreased antimicrobial efficacy in the urinary tract and increased systemic exposure leading to potential adverse effects 3.
- Patients should be advised to take Macrobid with food to improve absorption and reduce gastrointestinal side effects, and to complete the full course of treatment even if symptoms improve before completion.
- The clinical cure rates in nitrofurantoin ranged from 51 to 94% depending on the length of follow-up, and bacteriological cure rates ranged from 61 to 92% 3.
Renal Function and Nitrofurantoin Use
- A creatinine clearance of 64 mL/min is considered adequate for the use of nitrofurantoin, as it is above the threshold of 60 mL/min recommended for safe use 2.
- For patients with renal impairment, the use of nitrofurantoin should be carefully considered, and alternative treatments may be necessary if the creatinine clearance is below 30 mL/min.
Monitoring and Adverse Effects
- Close monitoring is advised for patients with a creatinine clearance of 30-60 mL/min, as they may be at increased risk of adverse effects.
- Patients taking nitrofurantoin reported fewer side effects than other drugs, and the most commonly reported were gastrointestinal and central nervous system symptoms 3.