Entacapone is used as an adjunctive medication for the treatment of Parkinson’s disease, usually in combination with levodopa/carbidopa.

I. Indications of Entacapone

1. Core Indications

(1) Entacapone is indicated as an adjunct to levodopa/carbidopa to improve end-of-dose “on-off” phenomena in patients with Parkinson’s disease.

(2) The end-of-dose phenomenon refers to symptom fluctuations between doses, characterized by alternating “on” periods (relatively good function) and “off” periods (relatively poor function).

2. Target Population Characteristics

(1) Studies were conducted mainly in Parkinson’s disease patients with motor fluctuations, taking levodopa 4–6 times daily on average.

(2) Results showed that entacapone significantly prolonged “on” time during the waking state, while the mean daily levodopa dose could be reduced by approximately 25%.

3. Limitations of Use

(1) Notably, the efficacy of entacapone in Parkinson’s disease patients without motor fluctuations has not been systematically evaluated.

(2) Entacapone has no antiparkinsonian effect on its own and must be used in combination with levodopa/carbidopa; it must not be used alone.

II. Contraindications of Entacapone

1. Absolute Contraindications

(1) Entacapone is contraindicated in patients with hypersensitivity to the active substance or any excipients of the product.

(2) Hypersensitivity reactions may include rash, itching, dyspnea, etc. If any such symptoms occur, the drug should be discontinued immediately and medical attention sought.

2. Contraindicated Drug Interactions

(1) Concomitant use of non-selective monoamine oxidase (MAO) inhibitors (e.g., phenelzine, tranylcypromine) with entacapone is contraindicated.

(2) These two classes of drugs inhibit the two major enzyme systems in catecholamine metabolism, respectively. Co-administration may cause excessive blockade of catecholamine metabolic pathways, leading to arrhythmias and severe blood pressure fluctuations.

(3) Selective MAO-B inhibitors (e.g., selegiline) can be used with entacapone; this combination was safely used in more than 600 patients in clinical studies.

3. Drugs Requiring Caution

Drugs metabolized by the COMT enzyme should be used with caution in combination with entacapone, including:

isoprenaline, adrenaline, noradrenaline, dopamine, dobutamine, α-methyldopa, apomorphine, isoetarine, bitolterol.

III. Special Populations Guidelines

1. Patients with Hepatic Impairment

(1) Entacapone should be used with caution in patients with hepatic dysfunction.

(2) Since entacapone is excreted mainly via bile, particular caution is required in patients with biliary obstruction.

2. Patients with Renal Impairment

No dosage adjustment is necessary in patients with renal insufficiency.

3. Pregnant Women

(1) Use during pregnancy requires a careful benefit-risk assessment.

(2) Entacapone must be combined with levodopa/carbidopa, which is known to cause visceral and skeletal malformations in rabbits. Due to the lack of human clinical data, use during pregnancy is only justified if the potential benefit outweighs the risk to the fetus.

4. Breastfeeding Women

(1) Caution should be exercised when used during breastfeeding.

(2) Since many drugs are excreted in human milk, breastfeeding women should weigh the benefits and risks under medical guidance, and consider temporary discontinuation of breastfeeding if necessary.

5. Elderly Patients

No special dosage adjustment is required for elderly patients.

6. Pediatric Patients

Safety and effectiveness in pediatric patients have not been established; use in the pediatric population is not recommended.