医療用医薬品とOTC薬の相互作用

―レボドパ製剤とOTC胃腸薬, サクロン^®―

抄録

In the present study, the possibility of an interaction between prescription drugs and over-the-counter (OTC) drugs was investigated by monitoring plasma drug concentrations in rats. When a levodopa preparation (Madopar^®) indicated for patients with Parkinson's disease was orally administered with Saclon^®, an OTC drug for upset stomach, the AUC and C_max for levodopa were significantly lowered and T_max was significantly prolonged. These results indicate that there may be an interaction between a levodopa preparation and Saclon^® when administered together, which leads to a reduction in the bioavailability of levodopa. Similar results were obtained when the levodopa preparation and the main ingredient of Saclon^®, a copper chlorophyllin salt, were concomitantly administered. Taken together, our results indicate that the copper chlorophyllin salt in Saclon^® may interact with levodopa preparations. The possibility of such an interaction should therefore be kept in mind during levodopa therapy for patients with Parkinson's disease.