Pharmacokinetic Interactions of Valsartan and Hydrochlorothiazide

Pharmacokinetic Interactions of Valsartan and Hydrochlorothiazide: An Open-Label, Randomized, Four-Period Crossover Study in Healthy Egyptian Male Volunteers

This study was conducted to compare the rate and extent of absorption of valsartan and hydrochlorothiazide following oral administration as a fixed dose combination tablet and concomitant administration of the individual drugs under fasting conditions in healthy Egyptian subjects. The study was extended to investigate any potential reaction between VAL and HCT.

This study comprised 2 separate parts, I and II; each was a single-dose, open-label, 4-crossover periods separated by a 2 weeks washout, and 4-Treatments. Part I consisted of Treatments A (VAL 160 mg alone), B (HCT 12.5 mg alone), C (VAL 160 mg + HCT 12.5 mg) and D (VAL / HCT 160 mg/12.5mg) and Part II consisted of Treatments E (VAL 320 mg alone), F (HCT 25 mg alone), G (VAL 320 mg + HCT 25 mg) and H (VAL / HCT 320 mg/25 mg). Blood samples were collected up to 48 hours postdose and plasma was analyzed for VAL and HCT concentrations using HPLC. The pharmacokinetic properties of each drug after co-administration of VAL and HCT were compared with those of each drug administered alone.

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.