Contrary to what was previously thought, creatine actually breaks down quite slowly in fluids.

The more acidic the fluid is, the faster it breaks down.

Yoghurt is acidic, yet creatine added to yoghurt still maintains its content rather well.

Probably because yoghurt is usually kept in the fridge, and creatine maintains its content better in low temperatures.

So making a peri-workout shake with creatine should be ok as long as you don't workout over 8 hours or in an oven