When Uny and I flew to Dallas back in January, we put the tincture bottles that we took with us in a seal-able baggie. That way, if there is any leakage it is contained within the baggie. When packing your suitcase, place the baggie in the center of the suitcase so it has all kinds of soft padding (clothes) all around it. You can also put some tape around the caps for extra security against leaks. Best to use black vinyl electrical tape.
I also noticed at the airport when entering the body scanning area, they had signs posted saying "No bottles in carry-on bags larger than 3 ounces". But I do believe we got through with a couple of 4 oz bottles in our carry-on bag.