To assess the safety and tolerability of lecozotan SR and citalopram when coadministred to healthy subjects.

Inclusion Criteria:

• Signed and dated IRB/IEC-approved informed consent form before any study-specific screening procedures are performed.
• Men or women aged 18 to 50 years, inclusive, at screening.
• Women of nonchildbearing potential, defined as being surgically sterile or postmenopausal for > 1 year, may be included. For women below 50 years of age, at least two years of retrospective amenorrhea and FSH>38 and estrogen <20 are required.
• Body mass index (BMI) in the range of 18.0 to 30.0 kg/m2 and body weight greater than or equal to 50 kg. BMI is calculated by taking the subject's weight, in kilograms, divided by the square of the subject's average height, in meters, at screening: BMI = weight (kg)/(height [m])2

Exclusion Criteria:

• Presence or history of any disorder that may prevent the successful completion of the study.
• Any clinically important deviation from normal limits in physical examination, vital signs, 12-lead ECGs, or clinical laboratory test results.
• Hypersensitivity to citalopram or any of the inactive ingredients in citalopram.