Development of a pharmacological evidence-based anticholinergic burden scale for medications commonly used in older...

The present study aimed to develop a pharmacological evidence-based anticholinergic burden scale (ABS) through a direct assessment of muscarinic receptor-binding activities of 260 medications commonly used in older adults.

The muscarinic receptor-binding activities of 260 drugs were assessed by the displacement of specific [N-methyl-³ H]scopolamine methyl chloride binding in the rat brain. The maximum blood concentrations (C_max ) of drugs after their administration to subjects were cited from their interview forms.

In total, 96 of 260 drugs displayed concentration-dependent muscarinic receptor binding in rat brain. Based on muscarinic receptor-binding activity (IC₅₀ ) and C_max after the administration at clinical doses in humans, we rated ABS 3 (strong) for 33 drugs and ABS 2 (moderate) for 37 drugs. There was an approximate similarity between muscarinic receptor-binding activities (IC₅₀ ) and C_max of 33 drugs (ABS 3) after their administration at clinical doses in humans. Furthermore, 26 drugs were defined as ABS 1 (weak) by muscarinic receptor-binding activity. The remaining 164 drugs exhibited slight or no significant muscarinic receptor-binding activities at high concentration of 100 μM, and they were defined as ABS 0. There was a marked similarity for 28 drugs (ABS 3) between the present ABS data and their previous scoring data in the literature.

To our knowledge, the present study developed the first comprehensive pharmacological evidence-based ABS of drugs based on muscarinic receptor-binding activity, which provides guidance as to which drugs may be discontinued to reduce anticholinergic burden. Geriatr Gerontol Int 2023; 23: 558-564.