Nitrofurantoin is not active against most strains of Proteus species or Serratia species. However, the efficacy of nitrofurantoin in treating clinical infections due to these microorganisms has not been established in adequate and well-controlled trials.Ĭoagulase-negative staphylococci (including Staphylococcus epidermidis) Īerobic and facultative Gram-positive microorganisms:Īerobic and facultative Gram-negative microorganisms:Īt least 90 percent of the following microorganisms exhibit an in vitro minimum inhibitory concentration (MIC) less than or equal to the susceptible breakpoint for nitrofurantoin.
Nitrofurantoin has been shown to be active against most strains of the following bacteria both in vitro and in clinical infections. Cross-resistance with antibiotics and sulfonamides has not been observed, and transferable resistance is, at most, a very rare phenomenon. The clinical significance of this finding is unknown.ĭevelopment of resistance to nitrofurantoin has not been a significant problem since its introduction in 1953. The broad-based nature of this mode of action may explain the lack of acquired bacterial resistance to nitrofurantoin, as the necessary multiple and simultaneous mutations of the target macromolecules would likely be lethal to the bacteria.Īntagonism has been demonstrated in vitro between nitrofurantoin and quinolone antimicrobials. Nitrofurantoin is bactericidal in urine at therapeutic doses. As a result of such inactivations, the vital biochemical processes of protein synthesis, aerobic energy metabolism, DNA synthesis, RNA synthesis, and cell wall synthesis are inhibited. Nitrofurantoin is reduced by bacterial flavoproteins to reactive intermediates which inactivate or alter bacterial ribosomal proteins and other macromolecules. The mechanism of the antimicrobial action of nitrofurantoin is unusual among antibacterials. Nitrofurantoin is a nitrofuran antimicrobial agent with activity against certain Gram-positive and Gram-negative bacteria. When nitrofurantoin monohydrate/macrocrystals capsules are administered with food, the bioavailability of nitrofurantoin is increased by approximately 40%. Nitrofurantoin is highly soluble in urine, to which it may impart a brown color. Plasma nitrofurantoin concentrations after a single oral dose of the 100 mg nitrofurantoin monohydrate/macrocrystals capsules are low, with peak levels usually less than 1 mcg/mL. Approximately 20-25% of a single dose of nitrofurantoin is recovered from the urine unchanged over 24 hours. Based on urinary pharmacokinetic data, the extent and rate of urinary excretion of nitrofurantoin from the 100 mg nitrofurantoin monohydrate/macrocrystals capsule are similar to those of the 50 mg or 100 mg nitrofurantoin macrocrystals capsule. The remaining 75% is nitrofurantoin monohydrate contained in a powder blend which, upon exposure to gastric and intestinal fluids, forms a gel matrix that releases nitrofurantoin over time. Twenty-five percent is macrocrystalline nitrofurantoin, which has slower dissolution and absorption than nitrofurantoin monohydrate. Each nitrofurantoin monohydrate/macrocrystals capsule contains two forms of nitrofurantoin.
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