Carbidopa/Levodopa and Norepinephrine Interaction
Drug interaction information between Carbidopa/Levodopa and Norepinephrine.
Carbidopa/Levodopa and Norepinephrine have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Carbidopa/Levodopa and Norepinephrine. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
These drugs are broken down by the same enzyme in the body. Taking them together can cause the drugs to build up, leading to a fast heart rate or high blood pressure.
FDA Label Information
7.2 Drugs 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 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 (5.10) ].
Carbidopa/Levodopa Also Interacts With
- Warfarin moderate
- Entacapone moderate
- Methyldopa moderate
- Dobutamine moderate
- Dopamine moderate
Norepinephrine Also Interacts With
- Tranylcypromine major
- Clopidogrel moderate
- Deutetrabenazine moderate
- Digoxin moderate
- Edoxaban moderate
Frequently Asked Questions
What SPL severity band is on file for Carbidopa/Levodopa + Norepinephrine?
Compiled FDA labeling labels this pair moderate. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Norepinephrine has 50 labeled pairs on file vs Carbidopa/Levodopa's 13. In the moderate band specifically: Carbidopa/Levodopa has 8 (also Warfarin, Entacapone, Methyldopa, Dobutamine); Norepinephrine has 7 (also Clopidogrel, Deutetrabenazine, Digoxin, Edoxaban).
What mechanism field is on file for Carbidopa/Levodopa and Norepinephrine?
These drugs are broken down by the same enzyme in the body. Taking them together can cause the drugs to build up, leading to a fast heart rate or high blood pressure.
Norepinephrine carries more major-labeled pairs than Carbidopa/Levodopa
SPL source-record counts only. This page's band is moderate · classes on file: Carbidopa/Levodopa (Dopamine Precursor Combination); Norepinephrine (Vasopressor (Alpha-1 Agonist)).
Norepinephrine has 1 major-labeled pair vs Carbidopa/Levodopa's 0. This page itself is in the moderate band, not the major band.
0 major · 8 moderate · 5 minor · 13 total
- Other moderate peers for Carbidopa/Levodopa
- Warfarin
- Entacapone
- Methyldopa
- Dobutamine
1 major · 7 moderate · 42 minor · 50 total
- Other moderate peers for Norepinephrine
- Clopidogrel
- Deutetrabenazine
- Digoxin
- Edoxaban
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.