Aula de Farmacologia - Resumão Anti-hipertensivos | Farmacologia Fácil | Prof. José Afonso

The main challenges in pharmacology are memorizing drug names and classifying them within pharmacological classes, particularly understanding their mechanisms of action. This lesson focuses on key medications used to treat systemic arterial hypertension, referencing the latest Brazilian guidelines from 2020, which include significant updates on treatment approaches.

The concept of stepwise therapy is introduced, emphasizing the importance of monitoring and adjusting treatment based on therapeutic goals. This involves adding or changing medications if the initial treatment does not lead to desired outcomes, highlighting the need for patient education on health and lifestyle habits to effectively manage chronic conditions like hypertension.

The discussion covers the main classes of antihypertensive medications, including diuretics (thiazides, loop diuretics, and potassium-sparing diuretics), adrenergic antagonists (beta-blockers and alpha-blockers), calcium channel blockers, direct vasodilators, and renin-angiotensin system antagonists. Each class's mechanism of action is briefly outlined, emphasizing their roles in managing hypertension.

The body's mechanisms for maintaining high blood pressure are explained, including the adrenergic control system and the renin-angiotensin-aldosterone system. The importance of understanding these mechanisms is highlighted for effective treatment, as they are crucial in the pathophysiology of hypertension.

Diuretics are discussed in detail, including osmotic diuretics and carbonic anhydrase inhibitors, which are less commonly used for hypertension. The primary focus is on loop diuretics like furosemide, which inhibit sodium and chloride reabsorption, leading to increased diuresis and reduced blood volume, thus lowering blood pressure.

Thiazide diuretics, such as hydrochlorothiazide, are introduced, explaining their mechanism of action in blocking sodium and chloride reabsorption in the distal convoluted tubule, leading to mild diuresis and potassium loss, which is less severe than with loop diuretics.

Potassium-sparing diuretics, including spironolactone and amiloride, are explained. Spironolactone acts as an aldosterone antagonist, reducing sodium reabsorption and potassium excretion, while amiloride directly blocks sodium channels, preserving potassium levels.

The adrenergic system is explored, detailing the roles of alpha and beta receptors in blood pressure regulation. Agonists and antagonists of these receptors are discussed, with a focus on medications like clonidine and alpha-methyl dopa, which reduce sympathetic outflow and lower blood pressure.