Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Entacapone
General information
Entacapone is an inhibitor of catechol-O-methyltransferase, which catalyses a relatively minor pathway of dopamine metabolism. It therefore enhances the action of dopamine.
The safety of entacapone has been specifically addressed in a Finnish study in 326 patients (mean age 62 years, 217 men) taking levodopa plus a decarboxylase inhibitor [ ]. Two-thirds were randomized to take entacapone 200 mg/day and the remainder to take placebo. The withdrawal rate due to adverse events was 14% with entacapone compared to 11% with placebo. Dyskinesias were greatly increased in the former (29% versus 11%) and entacapone was also associated with increased incidences of diarrhea (9.2% versus 1.9%), dry mouth (6.0% versus 0), and discolored urine (6.9% versus 0). However, there was no evidence of liver toxicity with entacapone.
Drug studies
Comparative studies
In 40 patients (mean age 64 years, 22 men) who took tolcapone for 3–7 months and were given entacapone in dosages titrated to 800–2000 mg/day after a transition period of 3–6 months with co-beneldopa, the improvements in “on” and “off” times were less impressive than they had been with tolcapone and there were more adverse effects [ ]. One patient had diarrhea and orthostatic hypertension with both drugs, but another six patients had increased dyskinesias and hallucinations and one developed myoclonus. There was no evidence of liver toxicity with either drug. The authors pointed out that entacapone, unlike tolcapone, not only increases the half-life of levodopa but also its peak concentration, causing significantly enhanced levodopa-related adverse effects. There is therefore a paradox: entacapone appears to be safer but overall causes more adverse effects.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here