A little dab will now do those men who have low testosterone levels. The Food and Drug Administration has approved Unimed Pharmaceuticals’AndroGel, a clear, testosterone-containing gel rubbed into the skin, as an alternative to current testosterone therapy. The prescription product comes in ketchup-like packets of natural testosterone, which men rip open, rub in the palm of their hands and then onto the skin of their shoulders or abdomens, according to Dr. Ronald S. Swerdloff, lead investigator of the study that led to the approval.