Inclusion Criteria:
1. Are capable of giving informed consent and complying with study procedures;
2. Male or female, 18 to 55 years of age, inclusive, at date of consent;
3. Body mass index (BMI) ≥ 18.0 to ≤ 32.0 kg/m2 and total body weight \> 50 kg (110 lbs.) at Screening;
4. All female subjects must have a negative pregnancy test at Screening and at each Check-in Visit; and one of the following:
1. Using a medically acceptable form of birth control for at least 1 month prior to first dose \[e.g., hormonal contraceptives (oral, patch, injectable or vaginal ring), intrauterine device, or a double barrier method (e.g., diaphragm, cervical cap, oral, patch or vaginal hormonal contraceptive, condom, spermicide, or sponge)\]
2. Documented as surgically sterile by hysterectomy, bilateral oophorectomy, bilateral salpingectomy, or bilateral tubal ligation/tubal occlusion) at least 6 months prior to the first dose;
3. Postmenopausal (no menstruation for a minimum of 12 months and confirmed by FSH and estradiol at Screening);
5. Medically healthy based on medical history, vital sign measurements, clinical laboratory test results, and physical examination;
6. Non-smokers (including nicotine-containing products) for at least 6 continuous months prior to the first dose.
7. Be willing and able to consume all contents of the standardized high calorie, high fat breakfast within 30 minutes prior to dosing.
Exclusion Criteria:
1. Females who are pregnant, lactating, or planning to become pregnant during the study;
2. Life-time history and/or recent evidence of alcohol or drug/substance abuse disorder;
3. Subjects with history of hypersensitivity to cetirizine or hydroxyzine, or any component of the test and reference formulations;
4. Subjects who test positive at Screening for human immunodeficiency virus (HIV), Hepatitis B surface antigen (HBsAg), or Hepatitis C virus (HCV) antibody;
5. Subjects who test positive at Screening or at Check-in for alcohol and/or drugs of abuse;
6. Subjects who donated ≥ 500 mL of blood within 56 days prior to the first dose of study drug or ≥ 50 mL and ≤ 499 mL of blood within 30 days or plasma (e.g. plasmapheresis) within 14 days prior to the first dose of study drug;
7. Use of prescription or non-prescription drugs, dietary supplements, or herbal supplements at the time of Screening and within 14 days prior to the first dose of the study drug;
8. Subjects who have a history of difficulty in donating blood or difficulty with phlebotomy procedures, and poor venous access;
9. Subjects who have participated in another clinical trial within 30 days prior to the first study period;
10. Member or first-degree relative of study staff or the Sponsor directly involved in the study;
11. Any condition which in the opinion of Investigator would interfere with the subject's ability to provide informed consent, comply with study instructions, confound interpretation of study results, or endanger the subject if he or she took part in the trial.
