no. pepto is made from bismuth amd milk is made from magnesium.
pepto-bismol is used manily for stomach upsets where milk of magnesia's primary role is to help alleviate constipation although there are cross overs.
the bismuth in pepto has been 'discussed' recently as in its natural state, bismuth is slightly radio-active as it is the last element before the real radioactive elemnets on the periodic table but its half life is very very long. both have their good and bad points so depends on what you want them for really as to which is best or whether something else is better, and if its for you or a child