Because of diet, genetics and other factors, some people just metabolize drugs a lot more slowly. As a result, the recommended dose of many chemotherapies will predictably make about 10 percent of patients very ill, and 1 or 2 percent of patients may die as a direct result of the treatment. This test will help the patient's oncologist adjust the dose without waste of precious time on ineffective dose levels while the disease progresses. What Watkins has invented is a simple breath test using a non-toxic drug. Patients preparing to take the chemotherapy take a trace dose of the common antibiotic erythromycin.
Doctors measure the amount of carbon dioxide they breath out.
Higher concentrations of exhaled carbon dioxide mean that patients are metabolizing erythromycin more quickly, and lower concentrations mean they are metabolizing it slower, Watkins said. The liver uses the same enzyme system, or pathway, to clear docetaxel as it does to process erythromycin. The antibiotic test gives an accurate prediction of how the patient's liver will handle Taxotere. The breath test takes about twenty minutes. Among other things, we found that the two patients who got very ill and had to be hospitalized showed the lowest test results and the lowest enzyme activity.