Can You Pre Mix Retin a and Cream/lotion and Store It in a Bottle?

I have sensative skin (mild rosacea, prone to hives & contact dermatitis). i want to use retin a .25% but it seems to really irritate my skin. I want to start slow and make my own retinol cream/lotion because I can use a lotion my skin is not allergic to like cevera. Can I mix up a batch and store it in a bottle or will pre mixing it degrade the active ingredient of the retin a rendering it ineffective? Also would you reccomend I use cream or lotion?