Hypertension Treatment & Management Guide I
Hypertension is a medical term for high blood pressure beyond normal ranges.
Anti-hypertensive drugs are medicines used to treat high blood pressure.
Hypertension is linked to stroke, myocardial infarction and cardiovascular disease.
In this section, we will deal with pharmacologic treatment of hypertension.
More about Hypertension is written here; Hypertension/High blood predsure.
9 most common drug classes used in treating and managing high blood pressure are;
- Diuretics
- Calcium channel blockers
- Beta blockers
- Angiotensin-converting enzyme (ACE) inhibitors
- Angiotensin II(AT II) receptor antagonists
- Alpha blockersAlpha-2 agonists
- Renin-inhibitors
- Endothelin receptor antagonists
- Vasodilators
We shall discuss in detail the each drug class; the examples, the specific mechanisms of action, side effects and any other relevant information
Diuretics
These group of drugs promotes renal and urinary loss of water. Specific drugs responsible for diuresis are;
- Loop diuretics-These act at the ascending limb(thick). These include Furosemide and bumetamide
- Thiazide and thiazide-like diuretics-These act at the DCT, distal convoluted tubule. Examlpes are Metolazone, hydrochlorothiazide.
Thiazide and thiazide-like diuretics are preferred as first line drugs for treating hypertension - Osmotic diuretics- Act at the proximal tubule eg Mannitol
- Carbonic anhydrase inhibitors-Act at the proximal tubule eg Acetazolamide, dorzolamide
- Potassium-sparing diuretics- Act at the cortical collecting duct eg Amiloride, Triamterene, Spironolactone
Mechanism of Action
- Loop diuretics-These act at the thick ascending limb
- Thiazide and thiazide-like diuretics-These act at the, distal convoluted tubule
- Osmotic diuretics- Act at the proximal tubule
- Potassium-sparing diuretics- Act at the cortical collecting duct
- These drugs are for removal of excess sodium and water.
- In their working, diuretic drug class can cause potassium ion imbalance. Several diuretic combinations are employed to balance and offset such risks.
Side effects
Side effects of diuretics include;
- Hypovolemia
- Hypokalemia(loop diuretics)
- Metabolic alkalosis
- Hypercalcemia(thiazides),
- Hyperkalemia(potassium-sparing diuretics like triamterene, spironolactone)
Calcium channel blockers
There are 2 groups of calcium channel blockers;
Dihydropyridines– first-line agents
- Nifedipine
- Felodipine
Non-dihydropyridines
- Verapamil
- Diltiazem
Mechanism of Action
They decrease entry of calcium ions into vascular and cardiac cells. Low intracellular calcium concentration causes relaxation and vasodilation of arterial smooth muscle.
Side effects
- Headache
- Flushing
- Constipation
- Shortness of breath
- Overgrowth of gums
Beta blockers
Employed where hypertension proves to be resistant to other treatment. Also, they can be used to potentiate anti-hypertensive effects.
Examples are;
- Propranolol
- Labetalol
- Timolol
- Carvedilol
- Nevibolol
Mechanism of Action
Beta blockers act on beta 1 receptors in the kidney organ to reduce secretion of renin. These affects the Renin-Angiotensin-Aldosterone System thereby reducing level of subsequent products such as aldosterone. Hypertensive effects become limited.
Side effects
- Bronchospasm
- Orthostatic hypotension
- Sexual dysfunction in males(impotence). These drugs should not be prescribed to males of reproductive age
- Reynaud’s disease
- Nausea
- Headache
ACE inhibitors
Examples are;
- Captopril
- Lisinopril
- Ramipril
Mechanism of Action
These group of drugs functions by inhibiting angiotensin-converting enzyme which is located on the surfaces of renal and pulmonary epithelia. Therefore, aldosterone release from adrenal cortex is prevented leading to renal elimination of sodium ions alongside water. Eventually, blood volume and blood pressure decrease.
Side effects
- Hypotension
- Dry cough
- Nausea
- Headache
- Hyperkalemia
- Fatigue
We are going to learn the remaining drug classes in Hypertension Treatment and Management guide II and guide III.