The objective of this study was to investigate the bioequivalence of Mylan's cetirizine HCl tablets to Pfizer's Zyrtec® tablets following a single, oral 10 mg (1 x 10 mg) dose administered under fed conditions.

Inclusion Criteria:

1. Age: 18 years and older.

2. Sex: Male and non-pregnant, non-lactating female

   1. Women of childbearing potential must have negative serum beta-human chorionic gonadotropin (HCG) pregnancy tests performed within 14 days prior to the start of the study and the evening prior to dosing of each study period. An additional beta-HCG pregnancy test will be performed upon completion of the study.

   2. Women of childbearing potential must practice abstinence or be using an acceptable form of contraception throughout the duration of the study. Acceptable forms of contraception include the following:

      1. hormonal contraceptives initiated at least 3 months prior to the start of the study and continued during the study, or
      2. intrauterine device in place for at least 3 months prior to the start of the study and remaining in place during the study period, or
      3. barrier methods containing or used in conjunction with a spermicidal agent, or
      4. postmenopausal or surgical sterility accompanied with a documented postmenopausal course of at least one year (tubal ligation, oophorectomy or hysterectomy).

   3. During the course of the study, from study screen until study exit - including the washout period, women of childbearing potential must use a spermicide containing barrier method of contraception in addition to their current contraceptive device. This advice should be documented in the informed consent form.

   4. Women are allowed to be taking hormone replacement therapy provided that the dosage regimen was initiated at least 3 months prior to the start of the study and continued from study screen until study exit.

3. Weight: At least 60 kg (132 lbs) for men and 48 kg (106 lbs) for women and all subjects within 15% of Ideal Body Weight (IBW), as referenced by the Table of "Desirable Weights of Adults" Metropolitan Life Insurance Company, 1999 (See Part II ADMINISTRATIVE ASPECTS OF BIOEQUIVALENCE PROTOCOLS).

4. All subjects should be judged normal and healthy during a pre-study medical evaluation (physical examination, laboratory evaluation, hepatitis B and hepatitis C tests, HIV test, 12-lead ECG, and urine drug screen including amphetamine, barbiturates, benzodiazepines, cannabinoids, cocaine, opiates, phencyclidine, and methadone) performed within 14 days of the initial dose of study medication.

Exclusion Criteria:

1. Institutionalized subjects will not be used.

2. Social Habits:

   1. Use of any tobacco products.
   2. Ingestion of any alcoholic, caffeine- or xanthine-containing food or beverage within the 48 hours prior to the initial dose of study medication.
   3. Ingestion of any vitamins or herbal products within the 48 hours prior to the initial dose of the study medication.
   4. Any recent, significant change in dietary or exercise habits.

3. Medications:

   1. Use of any medication within the 14 days prior to the initial dose of study medication, excluding hormonal contraceptives and replacement therapy initiated at least 3 months prior to study medication dosing.
   2. Use of any medication known to alter hepatic enzyme activity within 28 days prior to the initial dose of study medication, excluding hormonal contraceptives and replacement therapy initiated at least 3 months prior to study medication dosing.

4. Diseases:

   1. History of any significant cardiovascular, hepatic, renal, pulmonary, hematologic, gastrointestinal, endocrine, immunologic, dermatologic, neurologic disease.
   2. History of drug and/or alcohol abuse.
   3. Acute illness at the time of either the pre-study medical evaluation or dosing.

5. Abnormal and clinically significant laboratory test results:

   1. Clinically significant deviation from the Guide to Clinically Relevant Abnormalities (See Part II ADMINISTRATIVE ASPECTS OF BIOEQUIVALENCE PROTOCOLS).
   2. Abnormal and clinically relevant ECG tracing.

6. Donation or loss of a significant volume of blood or plasma (> 450 mL) within 28 days prior to the initial dose of study medication.

7. Subjects who have received an investigational drug within 30 days prior to the initial dose of study medication.

8. Allergy or hypersensitivity to cetirizine, any of the inactive ingredients, or other related products.

9. History of difficulties in swallowing, or any gastrointestinal disease which could affect the drug absorption.

10. Consumption of grapefruit or grapefruit containing products within 7 days of drug administration.