Entacapone

Primer

Entacapone is an inhibitor of catechol-O-methyltransferase (COMT). It is used in combination with levodopa/carbidopa (Sinemet) to treat the end-of-dose wearing-off effects of Parkinson's disease. Entacapone helps to increase levodopa and carbidopa levels.

Dosing

  • If deciding to add entacapone to each dose of levodopa, start with ½ tablet of entacapone for the first 2 weeks, and after these 2 weeks increase to 1 tablet per dose if tolerated.
  • If there is a problem with delayed kicking in, levodopa IR can also be crushed and taken with an acidic drink (e.g. - orange juice or a carbonated drink)
    • Break a tablet of levodopa into half, crush half of the tablet and mix with orange juice and swallow the mixture, then swallow the other half of the tablet, which can speed up the effect of the medication (or chew this half tablet and drink sufficient amounts of orange juice/carbonated drink/water with it).

Adverse Events

Impulse-Control Disorders (ICDs)

  • Impulse-control disorders (ICDs) such as compulsive gambling, buying, sexual, and eating behaviours, are a serious and increasingly recognized complication in Parkinson's disease (PD), occurring in up to 20% of PD patients over the course of their illness.
  • Related behaviours include punding (stereotyped, repetitive, purposeless behaviours), dopamine dysregulation syndrome (DDS), levodopa misuse (compulsive medication overuse), hobbyism (e.g. - compulsive internet use, artistic endeavours, and writing), and hypersexuality or paraphilias.
  • These disorders have a significant impact on quality of life and function, strain interpersonal relationships, and worsen caregiver burden, and are associated with significant psychiatric comorbidity.
  • Patients often do not report these behaviours due to shame or guilt, and so it is important to ask these questions directly!
  • Management includes decreasing the dose of the offending agent (usually a dopamine agonist) or completely stopping it.
    • It may take upto 4 months for ICD symptoms to dissipate after the agonist is discontinued.
    • Once patients gain insight into their behaviour they are at higher risk of suicide.