Clinical Pharmacology of Antihypertensive Agents

CLINICAL PHARMACOLOGY OF ANTIHYPERTENSIVE AGENTS

Hypertension presents a unique problem in therapeutics. It is usu-ally a lifelong disease that causes few symptoms until the advanced stage. For effective treatment, medicines that may be expensive and sometimes produce adverse effects must be consumed daily. Thus, the physician must establish with certainty that hyperten-sion is persistent and requires treatment and must exclude second-ary causes of hypertension that might be treated by definitive surgical procedures. Persistence of hypertension, particularly in persons with mild elevation of blood pressure, should be estab-lished by finding an elevated blood pressure on at least three dif-ferent office visits. Ambulatory blood pressure monitoring may be the best predictor of risk and therefore of need for therapy in mild hypertension. Isolated systolic hypertension and hypertension in the elderly also benefit from therapy.

Once the presence of hypertension is established, the question of whether to treat and which drugs to use must be considered. The level of blood pressure, the age of the patient, the severity of organ damage (if any) due to high blood pressure, and the pres-ence of cardiovascular risk factors all must be considered. Assessment of renal function and the presence of proteinuria are useful in antihypertensive drug selection. At this stage, the patient must be educated about the nature of hypertension and the importance of treatment so that he or she can make an informed decision regarding therapy.

Once the decision is made to treat, a therapeutic regimen must be developed. Selection of drugs is dictated by the level of blood pressure, the presence and severity of end organ damage, and the presence of other diseases. Severe high blood pressure with life-threatening complications requires more rapid treatment with more efficacious drugs. Most patients with essential hypertension, however, have had elevated blood pressure for months or years, and therapy is best initiated in a gradual fashion.

Education about the natural history of hypertension and the importance of treatment compliance as well as potential adverse effects of drugs is essential. Obesity should be treated and drugs that increase blood pressure (sympathomimetic decongestants, nonsteroidal anti-inflammatory drugs, oral contraceptives, and some herbal medications) should be eliminated if possible. Follow-up visits should be frequent enough to convince the patient that the physician thinks the illness is serious. With each follow-up visit, the importance of treatment should be reinforced and questions concerning dosing or side effects of medication encouraged. Other factors that may improve compliance are sim-plifying dosing regimens and having the patient monitor blood pressure at home.