However, despite the interactions with many other antibiotics, a clinical pharmacokinetic drug interaction study showed that oral administration of tetracycline HCl 500 mg for 3 days prior to and 7 days during use of Ortho Evra "did not reduce effectiveness of Ortho Evra." This is a significant factor in the common decision to administer tetracycline-derived antibiotics following an abortion (preventatively to fight potential infection) when synthetic hormone contraceptives are to be used afterwards.[citation needed]