The invention pertains to methods that include administering to a subject a transoral dosage form comprising a pharmaceutical carrier and sufentanil, and maintaining a mean pH ranging from about 3.5 to about 5.5 during a dosing period after administration of the transoral dosage form as determined using an in vitro donor media test. Related dosage forms are also disclosed. Also disclosed are transoral dosage forms and related methods, wherein a transoral dosage form may comprise: (1) about 5 to about 1000 micrograms of sufentanil; (2) about 50 micrograms to about 100 milligrams of naloxone; and (3) acidifying material in an amount sufficient to provide a mean pH ranging from about 3.5 to about 5.5 during a dosing period after administration of the transoral dosage form as determined using an in vitro donor media test; wherein the dosing period begins no earlier than about 1 minute after administration of the transoral dosage form, and ends no later than about 120 minutes after administration of the transoral dosage form.