Overview: Dexamethasone and betamethasone are the two antenatal corticosteroids (ACS) recommended for accelerating fetal lung development in threatened preterm birth. The WHO, NIH, ACOG, RCOG, and WAPM list both as effective drugs for preventing complications of prematurity, using either a dosage of 24 mg of dexamethasone (4 doses of 6 mg 12 hours apart) or 24 mg of betamethasone (2 doses of 12 mg 24 hours apart). Historically, these drugs have often been used interchangeably, but betamethasone has sometimes been preferred, as in the current WAPM guideline1,2.
As of July 2013, the 18th list of WHO Model List of Essential Medicines, which includes ACS for the first time, lists only dexamethasone for fetal indications.3 The Executive Summary of the WHO Expert Committee explains, “While alternative steroids with similar efficacy were available, dexamethasone was considered the most appropriate product based on availability and cost.”4
A review of the comparative efficacy, safety, availability, and cost reveals why dexamethasone is often the best choice for expanding the reach of life-saving ACS treatment.