Bioavailability File: Valsartan
Mehtap SAYDAM*, Sevgi TAKKA **^,°
* DROGSAN Pharmaceuticals, Department of Research and Development, 06760, Çubuk-ANKARA,TURKEY,
** Gazi University, Faculty of Pharmacy, Department of Pharmaceutical Technology, 06330, Etiler-ANKARA, TURKEY

° Corresponding author E-mail: takka@gazi.edu.tr

Summary

Valsartan is a new potent, highly selective and orally active antihypertensive drug belonging to the family of angiotensin II type 1 receptor antagonists. Valsartan has much greater affinity (about 20000 fold) for the angiotensin II type 1 (AT1) receptor than for the angiotensin II type 2 (AT2) receptor, thereby relaxing blood vessels and causing them to widen, which lowers blood pressure and improves blood flow. Valsartan is rapidly absorbed after oral administration. Plasma levels peak 2-4 h after oral administration and then decline with a terminal half-life reported in various studies in the range of 6–9 h. A peak plasma concentration (Cmax) of 1.64 mg/L occurred after oral administration of a single 80 mg dose of valsartan. A higher dose (200 mg) produced a proportionately higher Cmax (3.46 mg/L) at a similar time post-dose. The fraction of dose absorbed and systemically available after oral administration was 0.23 for the capsule and 0.39 for the solution, based on AUC. The absolute bioavailability is 10-35%. Food decreases the exposure to valsartan (as measured by AUC) by about 40% and peak plasma concentration (Cmax) by about 50%. There is considerable individual and between-subject variability (CV of 30%) in Cmax and AUC (CV of 44%). Volume of distribution and plasma clearance have been estimated at 17 L and 2.2 L/h, respectively; the drug is extensively bound to plasma proteins (85 to 99%). In this paper, the physicochemical properties, analytical determination methods, bioavailability, and pharmacology of valsartan are reviewed.

Key Words :
Valsartan, pharmacokinetics, bioavailability, hypertension, angiotensin II receptor inhibitors.