<p>Each capsule contains two forms of nitrofurantoin. Twenty-five percent is macrocrystalline nitrofurantoin, which has slower dissolution and absorption than nitrofurantoin monohydrate. 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. This capsule is highly soluble in urine, to which it may impart a brown color. When administered with food, the bioavailability of nitrofurantoin is increased by approximately 40%.</p>