"Higuain and Reina have passed their medicals and will soon join the group," De Laurentiis said on Twitter.
"We can say that we've worked really hard but we're not stopping there!"
Real Madrid forward Higuain, a reported target for both Arsenal and Juventus, is reported to be costing Napoli €37m plus an extra €3m based on bonuses.
Reina joins on loan from Liverpool and will link up with his former Anfield boss Rafael Benitez, who joined the Italians in the close season.
Last week Napoli sold Uruguay forward Edinson Cavani to Paris Saint-Germain for a French record €64m.