The problem is the discrepancy between the high D-number and the decreasing concentration of the medical drug. If you have D20 there is probably no drug molecule inside the pill.
This is typical of the ridiculous claims made by homeopaths. There is no physical/chemical method to perform such a dilution. There is no physical/chemical method to confirm such a dilution. If you prepare water by using the best possible means, this pure water will have on the order of 10-6 of anything you can propose in it.