Chirality Status of Withdrawn Drug Groups
Of the 395 drugs withdrawn, 52.4% (n=207) were achiral, 27.6% (n=109) were chiral mixtures, and 20.0% (n=79) were pure enantiomers. The mean TtW of all those drugs evaluated for safety were 24.6±27.5 (0-226) years, and the time after launch was 57.3±30.1 (8-267) years.
“N-nervous system drugs” had the highest share (26.3%) when distributed at ATC-1 level. Five of 13 ATC-1 classes were predominantly chiral. Furthermore, the chiral predominance in “C-cardiovascular system drugs” were statistically significant when compared to other classes (p=0.02), (Figure 1).
Chiral mixtures were significantly higher in number than achirals in cardiovascular system drugs (17.5% vs. 7.7%, p=0.01). In musculoskeletal system drugs, pure enantiomers were significantly less withdrawn (2.5%) compared to achirals (12.6%) and chiral mixtures (11.9%), (p=0.01 and p=0.03, respectively). On the contrary, pure enantiomers were subject to withdrawal at a higher rate (8.9%) compared to chiral mixtures (1.8%) in the genitourinary system drugs (p=0.04), (Table 1).