‣ Healthy Volunteers

• Healthy male and female adults, aged 18 to 55 years of age (inclusive) at the time of consent.

• Body mass index (BMI = body weight (kg)/\[height (m)\]2) between 18 kg/m2 and 32 kg/m2 (inclusive) at the time of Screening, and a minimum weight of 45 kg (inclusive).

• Clinically acceptable pulse rate, RR, and tympanic body temperature (pulse rate between 45 and 100 beats per minute \[bpm\]; SBP between 90 and 140 mmHg; DBP between 50 and 90 mmHg; RR between 12 and 22 breaths/min; tympanic body temperature between 35.5°C and 37.7°C at Screening and Day -1). Measurements are to be recorded after a minimum of 5 minutes of resting in sitting or supine position

• For Healthy Volunteers and Post-Herpetic Neuralgia Patients

• Clinical laboratory values within normal range as specified by the testing laboratory at Screening and Day -1, unless deemed not clinically significant by the Investigator.

• All participants (excluding those who are exclusively in same-sex relationships, who are postmenopausal or have an exclusive partner who is postmenopausal) must agree to use a highly effective method of contraception throughout the study and for at least 30 days for females or 90 days for males after the last dose of IP. Female participants must not be breastfeeding, lactating, or pregnant during the study period.

• Female participants are required to be on their chosen contraceptive for at least 7 days before dosing.

• Female participants, where their sole, male sexual partner is vasectomized, must provide a verbal confirmation of azoospermia (90 days following the procedure) which should be recorded in the source documents by the Investigator.

• The minimum timeframe for pre-dose vasectomy for male participants is ≥ 12 weeks, unless they are the sole sexual partner of a female participant as outlined above.

• Male participants who are sexually active must use a condom combined with use of a highly-effective method of contraception for the female partner (excluding those who have had a vasectomy or whose partner is postmenopausal). Confirmation of the female partner's contraceptive information must be provided verbally by the male participant and should be recorded in the source documents by the Investigator. The postmenopausal status of the female partner must be confirmed verbally by the male participant and should be recorded in the source documents by the Investigator.

• Cognitively capable of understanding the provided information and able to fully comply with protocol requirements.

• Written informed consent prior to the commencement of any study procedures.

• Willing and able to perform the necessary visits to the investigational site/institution.

• In good general health at the Investigator's discretion, with no significant medical history, and with no clinically significant abnormalities on physical examination at Screening and before the first dose of IP.

• Post-Herpetic Neuralgia Patients

⁃ Male and female adults aged 50 to 75 years of age (inclusive) at the time of consent.

⁃ Clinically acceptable blood pressure (BP), pulse rate, RR, and tympanic body temperature (SBP between 90 and 140 mmHg; DBP between 50 and 95 mmHg; pulse rate between 45 and 100 bpm; RR between 12 and 22 breaths/min; tympanic body temperature between 35.5°C and 37.7°C) at Screening and Day -1. Measurements are to be recorded after a minimum of 5 minutes of resting in sitting or supine position.

⁃ BMI (body weight (kg)/\[height (m)\]2) between 18 kg/m2 and 40 kg/m2 (inclusive) at the time of Screening, and a minimum weight of 45 kg (inclusive).

⁃ A diagnosis of neuropathic pain of PHN is confirmed when the pain for \>3 months after the herpes zoster rash is healed, with the pain area of a continuous area of affected rash.

⁃ Douleur Neuropathique 4 (DN4) score ≥4 at Screening.