Nitrofurantoin (Macrobid®, Macrodantin®)

Section 1.1

Midwives may independently prescribe, order and administer this drug.

Inhibits bacterial enzyme systems thus interferes with metabolism and cell wall synthesis.

Indications and Clinical Use:

For the prevention and treatment of urinary tract infections caused by susceptible gram-negative and some gram-positive organisms; E. coli, S. aureus, Enterococcus, Klebsiella, and Enterobacter. Pseudomonas, Serratia, and most species of Proteus are generally resistant to nitrofurantoin.


Contraindicated, at term (37-42 weeks), during labour, or when onset of labour is imminent as it may cause hemolytic anemia in infants, most often in the Mediterranean population.

Warnings and Precautions:

Caution is advised with G6PD deficiency or anemia. Although rare, severe hepatic reactions have been associated with nitrofurantoin (onset may be insidious); discontinue immediately if hepatitis occurs. Has been associated with peripheral neuropathy (rare); risk may be increased by renal impairment, diabetes, vitamin B deficiency, or electrolyte imbalance.


Human Data Suggest Risk in the 3rd Trimester


Category L2 – Limited Human Data – Probably Compatible
Use with caution in newborns at risk for hyperbilirubinemia.

Adverse Reactions:

Nausea, vomiting, diarrhea, drowsiness and dizziness, peripheral neuropathy (reversible) and respiratory symptoms (drug-induced pneumonitis).

Dosage and Administration:

Sustained release (commonly Macrobid®): 100 mg orally with food every 12 hours (bid) for 5 to 7 days, or
Regular release – 50-100 mg orally with food every 6 hours (qid) for 3 days if UTI is asymptomatic and 7 days if symptomatic.

Take with meals to improve absorption and decrease adverse effects.

Onset of Action:

Metabolized according to sustained or regular release. Slower absorption in sustained release.

Peak antibacterial concentrations: approximately 30 minutes.


20-60 minutes