There are two stores that reportedly sell Nembutal. These are Los Potrillos (Calle 41 177-I, Col Valladolid, Centro, Yucatan) and El Esfuerzo (which is diagonally opposite). The prices ranges from 450-600 pesos (USD23). The brand is Pisabental.
In late 2019, however, Exit received a report that neither of these pharmacies were willing to sell Pisabental. Both appeared disappointed at this development and the message was the same. The authorities were cracking down on the sale of the drug. This means that while in the past a trip to Valladolid was a sure thing, this may not now be the case.