Which drug should be administered to a newborn to prevent ophthalmia neonatorum?

Erythromycin is the appropriate drug to be administered to a newborn to prevent ophthalmia neonatorum. This condition, which involves inflammation of the conjunctiva and cornea in newborns, can be caused by the transmission of bacteria, such as Neisseria gonorrhoeae or Chlamydia trachomatis, from the mother during delivery. Erythromycin acts as an antibiotic that effectively prevents these infections by inhibiting bacterial protein synthesis, thereby limiting the risk of developing conjunctivitis.

The standard practice is to administer erythromycin as a prophylactic eye ointment shortly after birth, which is a crucial step in neonatal care. This preventive measure is particularly important in reducing the incidence of serious eye infections that could lead to complications, including blindness.

Other options, such as amoxicillin, loteprednol, and natamycin, do not serve the same purpose in this context. Amoxicillin is a broader-spectrum antibiotic but is not specifically indicated for ophthalmic use in newborns. Loteprednol is a corticosteroid used to reduce inflammation, not for infection prevention. Natamycin is an antifungal medication typically used for fungal infections, thus it does not address the bacterial causes associated with ophthalmia neonatorum.