Pharmacological rationale for antihypertensive drug treatment.

There are several first choices for mild and moderate hypertension. The selection of a drug may of course be influenced by concomitant pathology, with positive indications for particular drugs: for coexistent angina, a beta-receptor blocking drug or a calcium antagonist; for fluid retention, a diuretic; or for contraindications, e.g., asthma, a beta-adrenoceptor blocking drug. There are therefore several possible first choices: beta-adrenoceptor blocking drugs, a combined alpha/vasodilator beta-adrenoceptor blocking drug, the vasodilators (i.e., drugs acting primarily to reduce peripheral resistance), the calcium antagonists, alpha 1-blocking drugs, and, more recently, the possibility of angiotensin converting enzyme inhibitors. Diuretics are also possible first choice agents, although not quite so frequently as once was the case. The majority of cases of hypertension can usually be controlled by one drug, even if not the first agent chosen. More severe cases may require drugs from two of the three major groups: beta-blocking drugs, vasodilators, and diuretics are often required, and, in some cases, drugs from each group. Drugs such as methyldopa, clonidine, and the adrenergic neuron inhibitory drugs are now more used as reserve agents.