Br-PBTC is a highly potent, 2/4 subtype-selective positive allosteric modulator of nicotinic acetylcholine receptors (nAChRs). It specifically targets α2β2, α2β4, α4β2, α4β4, (α4β2)2α4, and (α4β2)2β2 subtypes of nAChRs, with EC50 values ranging from 0.1 to 0.6 μM. Br-PBTC exerts its activity by binding to the c-tail region of an α subunit.

Br-PBTC, within a concentration range of 0.01 to 10 μM, selectively influences the 2 and 4 subunits in HEK cells, with a notably higher impact on nAChRs featuring 2 subunits compared to those with 4 subunits when tested at 3 μM in oocytes. Furthermore, at a concentration of 3 μM, Br-PBTC enhances ACh-induced activation of α4β2 nAChRs by 385±61% within 50 seconds in oocytes and similarly reactivates short-term desensitized nAChRs. In HEK cells, Br-PBTC not only boosts channel activation to the maximum by ACh within 15 minutes but also reactivates both short-term and long-term desensitized nAChRs, with the latter observed over varying concentrations (0.1-100 μM) and durations (0 to 140 seconds).