Linezolid, while primarily known as an antibiotic, exhibits a notable inhibitory effect on both monoamine oxidase A (MAO-A) and monoamine oxidase B (MAO-B). This inhibition is non-selective, meaning it affects both enzymes to a similar degree.
This MAO inhibition is relatively weak compared to dedicated MAO inhibitors, but it’s clinically significant. Studies show Linezolid’s MAO inhibitory potency is roughly 10-20% of that seen with selective MAO inhibitors at therapeutic concentrations.
The consequence of this weak, yet present, MAO inhibition is a potential for serotonin syndrome, especially when Linezolid is co-administered with serotonergic drugs. Careful patient monitoring is crucial, and clinicians should avoid combining Linezolid with strong serotonergic agents where possible.
Specific studies reveal IC50 values (the concentration needed to inhibit enzyme activity by 50%) for MAO-A and MAO-B are in the micromolar range, highlighting the relatively lower potency compared to selective MAO inhibitors which operate in nanomolar ranges.
Therefore, while Linezolid’s primary mechanism is its antibiotic activity, its potential for MAO inhibition necessitates cautious prescribing practices, particularly in patients already taking medications affecting serotonin levels. Consider this interaction when prescribing Linezolid.
