How to break a while loop?

My while loop, it does not break, the function that I put to break it is ignored, and I would like to know how to fix it. to break when I enter the asterisk.

form itertools import cycle;
ewe=cycle([0]);
Nom_entrada="";
Agenda={};
Bucle_pricipal=True;
OpcionSelect="";
OpcionModificar=0;
while(Bucle_pricipal==True):

    for i in ewe:
        Nom_entrada=input("Deme un nombre para buscar: -> ");
        if (Nom_entrada==""):
            print("Entrada no valida");
        elif(Nom_entrada==" "):
            print("Entrada no valida");
        elif(Nom_entrada.isdigit()):
            print("Entrada no valida")
        elif(Nom_entrada=="*"):
            Bucle_pricipal=False;
            break;
        else:
            break;