Thanks for writing in.
is a category C drug, which means that there are no controlled studies for pregnant women. So the safety of this drug is largely unknown and it should be used only if the benefits outweigh the risks. I am sure your physician would have weighed this before prescribing this for you. Since you are already 22 weeks pregnant, the organ systems of your child have been formed and it is unlikely that this drug will affect your baby.
I hope this helps.