What the FDA labels say about taking them together
Carbidopa/entacapone/levodopa and isoproterenol
Carbidopa/entacapone/levodopa's FDA label of March 19, 2026 names isoproterenol in its drug interactions section; the isoproterenol label PlainMeds reads does not name carbidopa/entacapone/levodopa. The carbidopa/entacapone/levodopa label: “Metabolized by Catechol-O-Methyltransferase (COMT) Drugs known to be metabolized by COMT, such as isoproterenol, epinephrine, norepinephrine, dopamine, dobutamine, alpha-methyldopa, apomorphine, isoetherine, and …”
Check it at the source: the carbidopa/entacapone/levodopa FDA label on DailyMed (effective March 19, 2026, Sandoz Inc); the isoproterenol FDA label on DailyMed (effective December 16, 2025, Eugia US LLC).
What does the carbidopa/entacapone/levodopa label say about isoproterenol?
Carbidopa/entacapone/levodopa label, drug interactionsMetabolized by Catechol-O-Methyltransferase (COMT) Drugs known to be metabolized by COMT, such as isoproterenol, epinephrine, norepinephrine, dopamine, dobutamine, alpha-methyldopa, apomorphine, isoetherine, and bitolterol should be administered with caution in patients receiving entacapone regardless of the route of administration (including inhalation), as their interaction may result in increased heart rates, possibly arrhythmias, and excessive changes in blood pressure [see Warnings and Precautions (5.11) ].
Source: FDA drug label (Carbidopa, Levodopa, and Entacapone), NDA021485 (Orion Pharma), as published by Sandoz Inc, effective March 19, 2026 (SPL set 9c16c0e0-3b97-486b-b7d5-579f5853e2c5), via openFDA; the full label on DailyMed
What does the isoproterenol label say about carbidopa/entacapone/levodopa?
Isoproterenol's label (effective December 16, 2025) does not name carbidopa/entacapone/levodopa in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Isoproterenol Hydrochloride), Eugia US LLC, effective December 16, 2025 (SPL set 3e4050e8-7d94-4ed7-951d-1ff818ddadf1), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Carbidopa/entacapone/levodopa | Isoproterenol | |
|---|---|---|
| Labeled for | Parkinson's disease | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.695 per tablet 25-100-200 mg tablet | n/a |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once