Syncapone (Entacapone) Dosing for Parkinson's Disease
The recommended dose of entacapone is 200 mg taken orally with each levodopa/carbidopa dose, up to a maximum of 8 times daily (1,600 mg total per day). 1
Standard Dosing Protocol
- Administer one 200 mg tablet with every levodopa/carbidopa dose throughout the day 1
- Maximum daily frequency: 8 doses (total 1,600 mg/day) 1
- Clinical experience with doses exceeding 1,600 mg daily is limited and not recommended 1
- Entacapone can be taken with or without food 1
Critical Prescribing Principle
Entacapone has no antiparkinsonian effect when used alone and must always be administered in combination with levodopa/carbidopa. 1 The drug works by inhibiting peripheral catechol-O-methyltransferase (COMT), which prolongs levodopa's duration of action by approximately 30-40% 2, 3
Levodopa Dose Adjustment Requirements
When initiating entacapone, anticipate the need to reduce levodopa dosing in most patients:
- Patients taking ≥800 mg levodopa daily will likely require dose reduction (>58% needed reduction in clinical trials) 1
- Patients with moderate to severe dyskinesia before treatment will require dose reduction 1
- Average levodopa reduction in those requiring adjustment: approximately 25% 1
- In clinical practice, 35.8% of patients experienced levodopa dose reductions averaging 209 mg daily 4
Compatible Formulations
- Works with both immediate-release and sustained-release levodopa/carbidopa formulations 1
- Can be combined with selegiline therapy 2
Special Population Considerations
Hepatic Impairment
- Use with caution in patients with liver disease 1
- Entacapone AUC and Cmax approximately double in hepatic impairment 1
- Consider dose reduction or increased monitoring, though specific dosing adjustments are not established 1
Renal Impairment
- No specific dose adjustment required 1
Discontinuation Protocol
Never abruptly stop entacapone—taper gradually while monitoring closely. 1 Rapid withdrawal can cause:
- Emergence of parkinsonian symptoms 1
- Risk of hyperpyrexia and confusion resembling neuroleptic malignant syndrome 1
- Monitor patients closely and adjust other dopaminergic treatments as needed 1
Clinical Efficacy Expectations
When properly dosed, entacapone provides:
- Increased daily "on" time by up to 1.2 hours 5
- Decreased "off" time by 0.9-1.3 hours 5
- 40.8% of patients experience reduction in "off" time during waking hours 4
- Improvement in Unified Parkinson's Disease Rating Scale scores for activities of daily living and motor function 2, 4
Common Adverse Effects
- Dopaminergic effects (dyskinesia, nausea) are most common and related to enhanced levodopa activity 2, 6
- Diarrhea and abdominal pain occur but rarely lead to discontinuation 2
- Harmless urine discoloration (brownish-orange) occurs consistently 2, 6
- Dyskinesia was reported in 52.7% of patients but UPDRS dyskinesia scores actually improved slightly 4