Pharmacokinetics of Levodopa before and after Gastrointestinal Resection in Parkinson's Disease

INTRODUCTION Levodopa (LD) is important in the clinical treatment of Parkinson's disease (PD), and the changes of its pharmacokinetics may affect the clinical outcome. LD is mainly absorbed in the upper intestine; thus, the pharmacokinetics of LD may change after gastrointestinal operation. Here, we present the case of a patient who underwent resection of the intestine and compared his LD pharmacokinetics before and after resection. CASE PRESENTATION A 72-year-old Japanese male PD patient developed jaundice and was diagnosed with cholangiocarcinoma. Pancreaticoduodenectomy was performed and part of the stomach, total duodenum, and part of the jejunum were resected. The patient had been treated with LD, and his pharmacokinetics was checked twice at the age of 68 years. Because LD is absorbed in the duodenum and jejunum, we checked his pharmacokinetics again after the operation. The results before the operation were almost similar; however, in comparison, the area under the curve and peak drug concentration was reduced, and the time-to-peak drug concentration and elimination halftime were elongated after the operation. CONCLUSION Physicians must pay attention to the change of LD pharmacokinetics after gastrointestinal operation.