SUMMARY

* Moxonidine is a new centrally acting antihypertensive; it is a selective imidazoline receptor agonist (SIRA). Moxonidine has low affinity for central a₂adrenoceptors, and theoretically may cause fewer adverse effects than other centrally acting agents.

* In various shortterm clinical trials, moxonidine lowered blood pressure as effectively as clonidine, a thiazide diuretic, a b-blocker, a calcium channel antagonist and an ACE inhibitor.

* In studies, including a post-marketing surveillance study in Germany, the incidence of adverse effects with moxonidine has been low. Dry mouth, headache, dizziness and tiredness have been reported.

* Valsartan is the second angiotensinII receptor antagonist to be marketed in the UK. In the few published short-term studies, it lowered blood pressure as effectively as a thiazide diuretic, a calcium channel blocker and ACE inhibitors.

* The incidence of dry cough produced by valsartan is lower than that with ACE inhibitors.

* There is no evidence that either of these agents reduces morbidity or mortality. It is therefore difficult to justify their increased cost. A diuretic or bblocker remains a rational first choice treatment for most patients with hypertension.

* Neither agent should be considered a first choice therapy. Valsartan is a potential alternative to ACE inhibitors in patients who cannot tolerate them due to cough. Moxonidine may have a role when other agents are inappropriate or ineffective.