Some laboratory based research has for the first time given us a highly detailed view of the method of action of 2 recently approved treatments for the redness of rosacea.
The two treatments, brimonidine based Mirvaso, and oxymetazoline based Rhofade have been shown by this research to differ in their method of action.
Although brimonidine and oxymetazoline are both vasoconstrictors, as you can see from the graph, they have seemingly quite different receptor selectivity. What is receptor selectivity? it details the active parts of the inflamatory cells that the drug targets.
Is this why Rhofade might be gentler than Mirvaso?
The big question that then follows this research, is – does this just published difference in receptor selectivity explain the seeming difference between the user reviews that the treatments have received from rosacea sufferers, i.e. can it explain why Mirvaso appears to have had more adverse reports compared to Rhofade?
Or alternatively, could this response profile suggest that Rhofade is more generally applicable across a variety of sufferers’ redness symptoms?
Mirvaso is highly selective in operation
Brimonidine was shown to be highly selective for the α2 adrenergic receptors, specifically α2A, whereas oxymetazoline was found to be much less selective and was highly active against a wider range of targets.
Looking at the bar graphs above you can see
- Rhofade is broadly selective in operation
- Mirvaso is more highly selective in operation.
Article Extracts
Piwnica, D., Pathak, A., Schäfer, G. et al. Drugs R D (2018). https://doi.org/10.1007/s40268-018-0227-y
Objectives
The objective of this in vitro safety pharmacology study was to compare the potential safety profiles of brimonidine and oxymetazoline.
Methods
Brimonidine and oxymetazoline underwent pharmacological profiling with a standard panel of 151 assays, including α-adrenergic receptors and 5-hydroxytryptamine (5-HT) receptors. A valvular interstitial cell (VIC) proliferation assay was performed with oxymetazoline hydrochloride.
Results
Brimonidine was highly selective for the α2 adrenergic receptors, specifically α2A, whereas oxymetazoline was found to be much less selective and was highly active against a wide range of targets. Negligible activity was observed with brimonidine at the 5-HT2B receptor, whereas oxymetazoline had significant 5-HT2B receptor agonist activity and caused proliferation of mitral VICs in vitro.
Conclusion
As the 5-HT2B receptor is potentially involved in drug-induced valvulopathy, the benefit/risk ratio should be carefully considered, especially in patients with cardiovascular disease or other comorbidities.
Possible Heart Valve Risk for Rhofade
The paper’s main conclusion is that Rhofade may present an increased risk of heart valve damage (valvulopathy).
Study Funding
This study was supported by Nestle Skin Health R&D, Sophia Antipolis, France. Nestle Skin Health R&D are the owners of Galderma. Galderma makes a brimonidine based topical – Mirvaso. Allergan makes a competing oxymetazoline based topical – Rhofade.
Conflict of interest
As quoted in the article.
DP and GS are full-time employees of Nestle Skin Health/Galderma. AP has received consulting fees from Galderma for advisory meetings and manuscript writing and reviewing. JRD has served as an advisory board member for Galderma Laboratories. Galderma markets a brimonidine product for the topical treatment of persistent (nontransient) facial erythema of rosacea in adults 18 years of age or older.
