Doctor needs a refresher course on pinworm meds and basic human anatomy... The only OTC pinworm meds sold in the USA nowadays use pyrantel pamoate as the active drug. Pyrantel pamoate doesn't really get absorbed systemically,, it stays in the digestive tract and 85% of it simply passes thru unchanged, paralyzing susceptible species of helminths residing inside the GI tract so that normal bowel movement can push them out, hopefully before they can recover from their chemically induced paralysis . Only 15% gets absorbed where it quickly gets metabolized by the liver and excreted in urine. Last time I checked, the vagina wasn't part of the digestive tract and I don't think that configuration has changed since then.