The impact of chiral switch on drug labeling in Turkey: indication, posology, and adverse effects

Objective: Chiral switch, which involves replacing racemic drugs to market them as pure enantiomers, is presumed to improve efficacy and safety. Data on how chiral switch-related changes are represented in summary of product characteristics (SmPC) is scarce. We aimed to compare the indication, posology, and safety expressions in SmPCs of racemates and their pure enantiomers. Materials and Methods: We examined SmPCs of nine drug pairs (racemate/pure enantiomer) that underwent chiral switching among top 100 utilized active substances throughout Turkey. We evaluated the expressions in “indications”, “posology”, and “adverse effects” (AE) subheadings. Daily doses were examined based on “Defined Daily Dose” (DDD) metric. Results: We detected indication differences in four drug pairs, including absence of “peptic ulcer” in dexlansoprazole and “prevention of depression relapses” in escitalopram. DDDs of pure enantiomers decreased in most of the pairs. Recommended daily doses of esomeprazole and dexibuprofen per DDD were lower than their racemates. Cautions about use in renal and/or hepatic insufficiency varied in three pairs. AE expressions differed in seven drug pairs, mainly citalopram/escitalopram. Conclusion: This study demonstrated few indication differences in SmPCs of the drug pairs frequently used in Turkey and underwent chiral switching. However, dose reductions and distinctions in safety expressions were remarkable.