Hydrochlorothiazide/Telmisartan

Fixed-dose combinations of telmisartan and hydrochlorothiazide (HCTZ) [Micardis Plus, Micardis HCT, PritorPlus] are available in many countries for the treatment of patients with essential hypertension. Combining the angiotensin II receptor antagonist (angiotensin II receptor blocker [ARB]) telmisartan with the thiazide diuretic HCTZ provides antihypertensive therapy with complementary mechanisms of action. In the US and EU, telmisartan/HCTZ is approved for patients whose hypertension is not adequately controlled with telmisartan monotherapy; US labelling for the fixed-dose combination also includes inadequate control of blood pressure (BP) with HCTZ monotherapy.The antihypertensive efficacy of once-daily telmisartan/HCTZ has been demonstrated in several large, randomized trials in patients with stages 1 and 2 hypertension. The addition of HCTZ to telmisartan achieved significant reductions in BP in nonresponders to telmisartan monotherapy, and the antihypertensive efficacy of telmisartan/HCTZ was similar to or significantly greater than that of various comparator agents. Moreover, in studies that used ambulatory BP monitoring, telmisartan/HCTZ provided consistent 24-hour BP reductions throughout morning, daytime and night-time periods. The BP-lowering efficacy over the entire 24-hour dose administration interval is consistent with the pharmacokinetic profile of telmisartan, which has the longest elimination half-life among currently available ARBs and a unique chemical structure. Adverse events with telmisartan/HCTZ in clinical trials were typically mild and transient, and no unexpected events occurred that had not been previously reported with either telmisartan or HCTZ. Extensive tolerability data are available for telmisartan, in particular from the ONTARGET study, the largest clinical outcomes trial with an ARB. As such, fixed-dose combinations of telmisartan/HCTZ provide an effective, rational and generally well tolerated treatment option for the management of patients with hypertension.

Kinzalkomb marketed in Belgium by Bayer is a fixed combination of telmisartan 80 mg and hydrochlorothiazide 125 mg for the treatment of hypertension. New guidelines for the treatment of hypertension were recently released both in Europe and the United States (see article by J.M. Krzesinski in this issue). They offer the choice of using a fixed biotherapy even as first line treatment. Hydrochlorothiazide at low dose is a frequent component of such biotherapies: it is efficacious and secure. Telmisartan is a highly selective blocker of angiotensin II AT1 receptors ("sartans"); it is at least as effective as the classical antihypertensive agents; thanks to its half-life, the longest of all sartans', it provides adequate antihypertensive coverage throughout the whole 24-hour postdose interval and particularly over the last 6 hours of the dosage interval. Its tolerability profile is equivalent to placebo. The combination telmisartan-hydrochlorothiazide is more effective than each agent alone at lowering blood pressure; furthermore telmisartan possesses a potassium-sparing effect that when the two drugs are coadministered attenuates the kaliuretic effect of hydrochlorothiazide. Various large trials are currently under way (ONTARGET, TRANSCEND, PROFESS, PROTECTION, DETAIL). These studies which together involve some 50,000 patients will hopefully help to further specify the role of telmisartan in condition which require an intervention on the renin-angiotensin system.