I have a prescription for morphine 0.5% in Carbopolgel. I wondered if this was a good basis for processing morphine due to the pH and anionogenicity of Carbopolgel?

Your reaction is correct but there are still carbopolgels that contain cationactive medicines. You should try it and see what happens. It might well be that you need to add some drops of base extra maybe the gel will not stay bright because of the formation of a portion of morphine base. It is difficult in advance to be exactly predictable. If not, you need to switch from the be to a HPMC gel. Now in terms of dermatological properties nothing goes above Carbopol! This makes it already worth doing a small limited test at eg 25 g.