I'd never considered blister packs as an impulse control measure before; I had assumed it was for ease of dosing/packaging, and perhaps longer shelf-life (The US approach of (until relatively recent automation improvements) manually counting pills into a bottle always struck me as inefficient).
A short transcript[1] from the podcast agrees though, and there's a currently previous[2] and ongoing[3] research into packaging/impulsivity.
There's some other research as well that shows that restricting pack size of OTC paracetamol/acetaminophen reduces suicides, too[4]