Pharmacokinetic Interactions of Valsartan and Hydrochlorothiazide (Double Doses)

Inclusion Criteria: * At least 18 years old and not more than 45 healthy male volunteers * Actual weight no more than ± 30% from ideal body weight based on sex, height, and body frame * Who had passed all the screening parameters * Free of any drug exposure known to interfere with the pharmacokinetics or assay of fexofenadine for at least 10 days prior to the study * Who had to be able to communicate effectively with study personnel, be literate, and able to give consent. Exclusion Criteria: * A clinically significant abnormal physical exam, medical history, or laboratory studies * If they showed a sitting SBP of \>140 or \<100 mmHg, DBP \> 90 or \<60mm Hg, or a pulse rate of \> 95 or \< 50 beats/min at screening * A history of serious intolerance, allergy, or sensitivity to fexofenadine * The use of any prescription drug within the previous month or use of any over-the-counter medication (with the exception of acetaminophen) within the past 14 days * A history of blood dyscrasias * A history of alcohol or drug abuse within the past year * Donation of blood during the 8 weeks prior to the study or plans to donate blood during or within 8 weeks of completing the study * Unable to tolerate vein puncture and multiple blood samplings * Any surgical/medical condition that might alter drug absorption, distribution, metabolism, or excretion * Cannot follow instructions, in the opinion of the investigator.