ANTI-HYPERTENSIVE AGENTS

Hypertension is a disease characterized by abnormally high blood pressure. Hypertension may be primary for which the exact cause is not known or secondary which may be due to renal, endocrine or vascular lesions. It may give rise to degenerate changes on cerebral. coronary, renal and retinal tissues. Antihypertensive drugs are ușed to treat hypertension.

Blood pressure is expressed in terms of the arterial systolic and diastolic pressure. A normal adult blood pressure is a systolic pressure equal to or below 140 mm Hg (18.7 KPa) together with a diastolic pressure equal to or below 90 mm Hg (12.0 KPa). The blood pressure depends on two important factors - (1) force of contraction and rate of beating of heart, and (2) resistance of blood flow caused by inner diameter of the blood vessels. Besides these, the viscosity (thickness) and volume of blood may also affect the blood pressure. Emotional trauma or excitement, physical excerise or exertion increase the heart rate which experienced in the form of palpitation, resulting in a rise of blood pressure. This is generally for a short period and does not require any treatment. The dangerous form of high blood pressure is due to narrowing of the lumen of the blood vessels and must be treated immediately. Normal blood pressure of a person may vary from person to person depending on age, sex, heredity, nutrition, body weight, etc.

he antihypertensive agents discussed here include Rauwolfia alkaloids, the Veratrum alkaloids, and an unclassified group.