The IMSS doctors I talked with*, said 10% is the choice of private physicians and with eight to ten subcutaneous injections around the site being norm. Sub milliliter jabs. They also told me pain treatment for alacranes was elective therefore not in their formulary. They use lidocaine on stuff that needs to be stitched.
*Ensenada, Morelia, Seguro Publico La Mira.
You might find a dentist that would administer plain Novocaine without Epinephrine.
I used to purchase 100ml spray bottles of Lidocaine for about eighteen dollars. Then drug addicts moved in... Best sunburn and roadrash spray I ever used.