Alexandrite laser after Efucal?

Hi. Last year I was treated with the Alexandrite laser on portions of my skin that were a bit brown from sun damage and it worked well. About a week ago, at the direction of another dermatologist, I applied Efucal to an actinic keratosis on my nose and a pre-actinic keratosis near my cheekbone. I got almost no reaction at all and the brown spots are unchanged. How soon can I undergo an Alex treatment of the same cheekbone area? Thank you!