What is a blue capsule with brown powder in it with no marking?

"No Imprint Code? All Rx and OTC drugs in the US are required by the FDA to have an imprint. If your pill has no imprint it could be a vitamin, diet/herbal/energy pill, illicit or foreign drug and will not be included in our pill identifier.

A solid oral dosage form drug product that does not meet the requirement for imprinting and is not exempt from the requirement may be considered adulterated and misbranded and may be an unapproved new drug as defined by the FDA. Also, if a pill or capsule has no imprint and is not an approved medication it may be a vitamin or other dietary supplement, illegal drug of abuse, foreign medication or even candy."

I'd recommend you consult a pharmacist who might recognize this capsule or you could try the Poison Control Centers at (800) 222-1222.
Good luck!