Table 5

Effect of COMT inhibitors entacapone, nitecapone, and tolcapone on pharmacokinetics and metabolism of l-dopa in healthy subjects after single dose administration in combination with levodopa and carbidopa (100 and 25 mg)

ParameterEntacapone5-aNitecapone5-bTolcapone5-c
100 mg200 mg100 mg100 mg200 mg
T max No changeNo changeNo changeNo changeNo change
C max No changeNo changeNo changeNo changeNo change
AUC ofl-dopa+29%+42%+20%+50%+88%
T ½ of l-dopaNo changeNo changeN.A.+32%+60%
AUC of 3-OMD−35%−46%−48%−64%−64%
AUC of DOPAC+149%+214%+120%+175%+253%
AUC of HVANo changeNo change−37%−52%−54%
  • N.A., not available.

  • 5-a Keränen et al., 1993.

  • 5-b Kaakkola et al., 1990.

  • 5-c Sedek et al., 1997.