Melatonin to mexamine instructions

It seems like you might be looking for information on how to convert melatonin dosage into "mexamine" or perhaps another substance or dosage format. However, "mexamine" does not appear to be a widely recognized term or medication in medical literature. If you meant to ask about a specific conversion, formulation, or dosage guidelines pertaining to melatonin or another medication, please clarify your question. Additionally, always consult a healthcare professional before making any changes to your medication regimen or if you have questions about drug interactions or dosing.