Patient/caregiver was educated on precautions to be exercised while taking phenazopyridine as follows:
- Metabolism of phenazopyridine in the liver also yields another metabolite called aniline. This metabolite aniline can be dangerous to the hemoglobin, which is the compound in the red blood cells carrying oxygen to various body tissues. Aniline, especially when produced in increasing amounts, can convert hemoglobin to another potentially dangerous compound, methemoglobin. Methemoglobin poorly delivers oxygen to tissues and can discolor the skin and mucus membranes from normal pink to blue. When the levels of methemoglobin in the blood are high, individuals can present with blue colored skin and mucus membranes and display symptoms of compromised oxygen levels in the body tissues, such as, increasing shortness of breath, fatigue, rapid heart rate, confusion, and episodes of loss of consciousness. While taking phenazopyridine, report development of any of these findings immediately to your physician, so that, an appropriate change in plan of care could be considered.
- Phenazopyridine is partially metabolized in the liver to some active metabolites. If liver function is deficient, the metabolism of phenazopyridine could be compromised. This can lead to increased blood levels of the medication for longer periods of time, resulting in increased risk for side-effects and consequent toxicity. Also, acetaminophen, one of the active metabolites of phenazopyridine, carries significant risk for liver injury. So, in individuals with history of compromised liver function, phenazopyridine must be used with caution and possible dose adjustments, periodical monitoring for liver functions and development of any toxicity symptoms with the medication.
