Otenzepad
# Otenzepad

Otenzepad is a competitive muscarinic receptor antagonist that is relatively selective at the M2 receptor. It was investigated as a treatment for arrhythmia and bradycardia due to its cardioselectivity but research ceased after stage III clinical trials. The drug was originally developed by the German pharmaceutical company, Boehringer Ingelheim Pharma KG.

## Pharmacodynamics

The (+)-enantiomer has 8 times greater potency at the M2 receptor than the (-)-enantiomer.

Potency of Otenzepad at muscarinic receptor isoforms :

| mAChR isoform | Dissociation constant $(K_i)$ |
| - | - |
| M1 | 537.0 - 1300nM |
| M2 | 81.0 - 186nM |
| M3 | 838 - 2089.0nM |
| M4 | 407.0 - 1800nM |
| M5 | 2800nM |
