Prilocaine for Bier's block needs methylene-blue but not preservative.
D005260:Female; D006801:Humans; D008751:Methylene Blue; D009407:Nerve Block; D011310:Preservatives, Pharmaceutical; D011318:Prilocaine / Q000008:administration & dosage*
D011310:Preservatives, Pharmaceutical; D011318:Prilocaine; D008751:Methylene Blue