Can't help you there, but Walgreens used to carry them.
Though I have still a bottle of Oxypowder , I find it easier to use Epsom Salts .
Since changing my lifestyle I usually don't need it and I also started taking a pinch of ES in my food.
Right now, since a week, I put 1/2 tsp in my daily water for the magnesium, since my feet were cramping.