Sublingual Atropine Bioequivalence by Route of Administration (SABER)

This is a randomized, two-period, two-sequence, crossover study to assess the bioequivalence, bioavailability, and pharmacokinetics (PK) of a single dose of atropine administered SL or IM in healthy adult volunteers. A total of 46 healthy male and non-pregnant female volunteers will be randomized, with the goal of obtaining at least 36 evaluable participants in the per protocol population. Additional participants may be randomized if participants are withdrawn prior to receiving one or both doses of study drug. Eligible participants will be randomized at a 1:1 ratio to receive one of two treatment dosing sequences (A \[Visit 1 SL, Visit 2 IM\] or B \[Visit 1 IM, Visit 2 SL\]). Volunteers will be screened for study participation from Days -14 to -3. Eligible participants will be enrolled and randomized to receive one of two dosing sequences (Sequence A or Sequence B) until the target enrollment for the study is met. Once randomized, each participant will receive 2 doses of atropine separated by a wash out period of 6 ±1 days. During Visit 1 (Day 1) and Visit 2 (Day 8), participants will be administered SL or IM atropine, according to their randomly assigned dosing sequence. At each dosing visit, blood samples for PK will be collected at time 0 (pre-dose) and at 13 time points post-dose at 5, 10, 15, 20, 30, 45, 60, and 90 minutes and 2, 2.5, 4, 6, and 8 hours after dosing. Participants will be discharged from the clinic after the 8-hour blood sample collection. Participants will be followed for approximately 6 days after their last dose.