How much calamine lotion in a bath for an adult?

Calamine lotion. it actually works better to use aveeno oatmeal bath in the bathtub rather than calamine lotion for itching. This comes in little packages at the drug store. Calamine lotion doesn't mix very well and causes a huge mess .
Calamine lotion. Should be applied directly to the affected portion of the skin and is NOT generally used in a bath! Is this a calamine "containing" bath preparation??