Agomelatine and Melatonin Pharmacodynamic Relationship
Agomelatine is a melatonin receptor agonist at MT1 and MT2 receptors. [1] Melatonin is also a melatonin-receptor ligand, so concurrent use can be expected to produce overlapping pharmacodynamic (melatonin-receptor) effects. [1]
Agomelatine and Melatonin Pharmacokinetic Interaction Potential
Agomelatine is metabolized mainly by cytochrome P450 1A2 (CYP1A2). [1] Agomelatine does not inhibit CYP1A2 in vivo and does not induce CYP450 isoenzymes in vivo. [1] Melatonin metabolism is mediated mainly by CYP1A2, which creates a mechanistic basis for interaction with drugs that affect CYP1A2 activity. [2]
Effect of Coadministered Melatonin on Agomelatine Exposure
No specific evidence in the available regulatory interaction information establishes that melatonin changes agomelatine pharmacokinetic exposure. [1] Because agomelatine has no known inhibitory effect on CYP1A2, clinically meaningful melatonin-driven increases in agomelatine exposure are not supported by the available interaction data. [1]
Effect of Coadministered Agomelatine on Melatonin Exposure
No specific evidence in the available regulatory interaction information establishes that agomelatine changes melatonin pharmacokinetic exposure. [1] Because agomelatine is not an inhibitor of CYP1A2 in vivo, melatonin metabolism via CYP1A2 is not expected to be directly suppressed by agomelatine based on available data. [1,2]
Practical Interaction Considerations in Clinical Use
Concomitant therapy may increase melatonergic effects such as sleep-related effects due to receptor-level overlap. [1] Coadministration is not addressed as a special interaction in regulatory CYP1A2 interaction statements, which focus on CYP1A2 inhibitors increasing agomelatine exposure rather than on melatonin. [1]
Coadministration With Agents That Alter CYP1A2 as the Main Interaction Risk
Strong CYP1A2 inhibitors (for example, fluvoxamine and ciprofloxacin) are contraindicated with agomelatine due to marked increases in agomelatine exposure. [1] This CYP1A2-centered interaction risk is clinically relevant because melatonin metabolism is also mediated mainly by CYP1A2. [2]
Monitoring and Safety Signals
Agomelatine is associated with risk of liver injury in post-marketing reports, so liver function monitoring is part of safe agomelatine use and is not specific to melatonin coadministration. [1] Caution with additive sedation or sleep-phase effects is clinically relevant when receptor-level melatonergic pharmacodynamics overlap, although specific combined-dose adverse-event rates are not provided in the available interaction information. [1]
Key Evidence Base
Agomelatine acts as an MT1/MT2 melatonin-receptor agonist and is metabolized mainly by CYP1A2. [1] Melatonin 6-hydroxylation is mediated mainly by CYP1A2, supporting a mechanistic interaction pathway for CYP1A2 modulators rather than requiring a direct agomelatine–melatonin pharmacokinetic interaction. [2]
Sources and Interaction Summary
Available regulatory interaction information supports that agomelatine–melatonin concerns are primarily pharmacodynamic overlap at melatonin receptors and CYP1A2-mediated effects driven by other concomitant medications rather than a well-defined direct pharmacokinetic interaction between agomelatine and melatonin. [1,2]