This is a first-in-human, randomized, double-blind, placebo-controlled Phase 1 single ascending dose (SAD) and multiple ascending dose (MAD) study to evaluate the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of orally administered LTG-321 in healthy male and female participants 18 to 55 years of age. The study will be conducted in New Zealand.

The study also includes a randomized, double-blind, placebo-controlled, within-participant crossover evaluation of pain tolerance using a cold pressor test in healthy male participants 18 to 55 years of age. In addition, a randomized, open-label, crossover Food Effect cohort will evaluate the impact of a high-fat meal on the pharmacokinetics of LTG-321 following single oral doses in the fed and fasted state.

Inclusion Criteria:

• Male and female participants aged 18 to 55 years, inclusive, at the time of signing the informed consent.
• Overtly healthy with no clinically relevant abnormalities based on the medical history, physical examinations, clinical laboratory evaluations, and 12-lead ECG that, in the opinion of the investigator, would affect participant safety.
• Body mass index (BMI) within the range of 18-30 kg/m2 (inclusive).

Exclusion Criteria:

• Inability to take oral medications or gastrointestinal abnormalities potentially impacting absorption.
• Clinically significant cardiovascular, hematological, renal, hepatic, pulmonary, endocrine, gastrointestinal, immunological, dermatological, neurological, or psychiatric disease which could interfere with, or the treatment for which might interfere with, the conduct of the study or which would, in the opinion of the investigator, unacceptably increase the participant's risk by participating in the study.
• Past or current history or evidence of alcohol abuse and/or dependence on recreational drug use
• Donation of over 500 mL blood ≤ 3 months prior to start of participation
• Participant is under legal custodianship.