are a class of drugs that are used to treat hypertension (high blood pressure)
- Antihypertensive therapy seeks to prevent the complications of high blood pressure, such as stroke and myocardial infarction.
- There are many classes of antihypertensives, which lower blood pressure by different means
- Among the most important and most widely used drugs are thiazide diuretics, calcium channel blockers, ACE inhibitors, angiotensin II receptor antagonists (ARBs), and beta blockers.
- Which type of medication to use initially for hypertension depends with Patient age, associated clinical conditions and end-organ damage also play a part in determining dosage and type of medication administered.[
- The best available evidence favors the thiazide diuretics as the first-line treatment of choice for high blood pressure when drugs are necessary.
- Although clinical evidence shows calcium channel blockers and thiazide-type diuretics are preferred first-line treatments for most people (from both efficacy and cost points of view)
- An ACE inhibitor is recommended for those under 55 years old.
- A diuretic is any substance that promotes the production of urine.
- There are several categories of diuretics
- All diuretics increase the excretion of water from bodies, although each class does so in a distinct way.
- THIAZIDES DIURETICS
MECHANISM OF ACTION
- Thiazide-type diuretics such as hydrochlorothiazide act on the distal convoluted tubule
- inhibit the sodium-chloride reabsorption hence leading to a retention of water in the urine.
- through that mechanism they decrease blood pressure
- Frequent urination is due to the increased loss of water that has not been retained/reabsorbed in the body
- Allergy to sulphur
- Diabetic patients
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- Treatiment of edema
- SIDE EFFECTS
DRUGS UNDER THIS GROUP
- BENDROFLUMTHAZIDE ( APRINOX)
The main use of bendroflumethiazide currently is in hypertension
- strength 2.5mg or 5mg
- Dose-2.5mg or 5mg in morning with or without food
- postural hypotension
- hyponatraemia, hypokalaemia, hypercalcaemia
- impaired glucose tolerance
- pulmonary oedema
- Bendroflumethiazide is known to have an adverse interaction with alcohol.
- It is advised that those using this diuretic should abstain from alcohol consumption during use, as it is possible to experience a sudden drop in blood pressure, especially if standing up.
- Other considerations
- Bendroflumethiazide should not be used by pregnant women, or women who have just given birth.
- Due to the nature of the medication, it is possible for it to pass into the breast milk and consequently to the child.
- It is also known that bendroflumethiazide suppresses the production of breast milk.
- is a diuretic medication often used to treat high blood pressure and swelling due to fluid build up
- For high blood pressure it is often recommended as a first line treatment
- It may be used during pregnancy but is not a first line medication in this group.
- Strength 12.5mg
- Most of the time appear in combination with other antihypertensives
- Hypokalemia, or low blood levels of potassium are an occasional side effect. It can be usually prevented by potassium supplements or by combining hydrochlorothiazide with a potassium-sparing diuretic.
- hypomagnesemia (low magnesium), hyponatremia (low sodium), and hypercalcemia (high calcium).
- Hyperuricemia, high levels of uric acid in the blood.
- Hyperglycemia, high blood sugar. Hyperlipidemia, high cholesterol and triglycerides.
- Weight gain
- Gout Pancreatitis
- Loop diuretics are diuretics that act at the ascending loop of Henle in the kidney. They are primarily used in medicine to treat hypertension and edema often due to congestive heart failure or renal insufficiency. While thiazide diuretics are more effective in patients with normal kidney function, loop diuretics are more effective in patients with impaired kidney function.
Mechanism of action
- Loop diuretics act on the Na+-K+-2Cl− symporter (cotransporter) in the thick ascending limb of the loop of Henle to inhibit sodium, chloride and potassium reabsorption
- As a result sodium and chlorine will be excreted together with water in urine to lower blood pressure
- for treatment of edema and hypertension
- Adverse effects
- hyponatremia, hypokalemia, hypomagnesemia, dehydration, hyperuricemia, gout, dizziness, postural hypotension,
- Treatment of edema and hypertension
- Adverse effects
ototoxic,gout caused by hyperuricemia. Hyperglycemia
- Thiazide diuretics are effective in patients with normal kidney function while loop diuretics are effective in patients with impared kidney functions
Potassium Sparing Diuretic
- Spironolactone, a steroid derivative, is a pharmacologic antagonist of aldosterone in the collecting tubules.
Mode of Action
- Potentiates thiazide or loop diuretics by antagonising aldosterone; it is a potassium-sparing diuretic.
- drug: Spironolactone(aldactone)
- As the name implies, vasodilator drugs relax the smooth muscle in blood vessels, which causes the vessels to dilate.
- Dilation of arterial (resistance) vessels leads to a reduction in systemic vascular resistance, which leads to a fall in arterial blood pressure. Dilation of venous (capacitance ) vessels decreases venous blood pressure.
- is a direct-acting smooth muscle relaxant used to treat hypertension by acting as a vasodilator primarily in arteries and arterioles.
- By relaxing vascular smooth muscle, vasodilators act to decrease peripheral resistance, thereby lowering blood pressure
- Hydralazine is not used as a primary drug for treating hypertension because it elicits a reflex sympathetic stimulation of the heart (the baroreceptor reflex). The sympathetic stimulation may increase heart rate and cardiac output,
- Hydralazine may also increase plasma renin concentration, resulting in fluid retention
- To prevent these undesirable side effects, hydralazine is usually prescribed in combination with a beta-blocker (e.g., propranolol) and a diuretic
- Hydralazine is used to treat severe hypertension,
- hydralazine is the first-line therapy for hypertension in pregnancy, with methyldopa
- High heart rate
- Flushing Hypotension
- Anginal symptoms
- Joint ache
- In human body there are different types of beta receptors
- Three types of beta receptors are b1, b2,b3
- B1 receptros are located in heart,kidney
- B2 receptros are located in lungs,gastrointenstinal tract, liver, uterus, vascula smooth muscles, skeletal muscles,
- B3 receptors are found in fat cells
- When beta 1 receptos are stimulated by epinephrine the following effects occurs
- Increase cardiac output
- Increase heart rate(positive chronotropic effect)
- Increase atrial cardiac muscle contractility(postive inotropic effect)
- Increase renini release
- Increase lipolysis in adipose tissue
- These receptors are located in lungs
- Upon stimulation by epinephrine they cause smooth muscles relaxation and bronchodilatation
Cardiosellective beta blockers
- Beta blockers are drugs which prevents stimulation of the beta receptors and there fore decrease activity of the heart.
- They reduce stimulation of heart, reduce systolic pressure,heart rate, cardiac contractility and cardiac output
- Beta blockers are used to reduce high blood pressure however in doing so they may cause bronchial constriction
- To avoid such effect we use cardioselective beta 1 blockers which will act on heart only(beta 1 receptors)not on lungs( beta 2 receptors)
- But they are not totally selective
Examples of cardioselective beta 1 blockers are
Uses of beta blockers
- High blood pressure
- Chest pain (angina)
- Heart attack
- Anxiet disorders
- In asthmatic patients
- In diabetic patients
ANGIONTESIN CONVERTING ENZYME INHIBITORS
- These are drugs used for treatment of hypertension and congestive heart failure
- MECHANISM OF ACTION
- They inhibits the angiotensin-converting enzymes hence they cause relaxation of blood vessels as well as decrease blood volume, which leads to lower blood pressure
ANGIONTESIN CONVERTING ENZYME INHIBITORS
Frequently prescribed ACE inhibitors include
- Medical use
- ACE inhibitors were initially approved for the treatment of hypertension and can be used alone or in combination with other antihypertensive medications. Later, they were found useful for other cardiovascular and kidney diseasesincluding:
- Acute myocardial infarction (heart attack)
- Cardiac failure (left ventricular systolic dysfunction)
- In treating heart disease, ACE inhibitors are usually used with other medications. A typical treatment plan often includes an ACE inhibitor, a beta blocker, a long-acting nitrate, and a calcium channel blocker,
and renal impairment
Calcium channel blocker
- are several medications that disrupt the movement of calcium (Ca2+) through calcium channels
- Sometimes when they are used to
treat angina, the vasodilation and hypotension can lead to reflex tachycardia, which can be detrimental for patients with ischemic symptoms because of the resulting increase in myocardial oxygen demand.
- They have minimal vasodilatory effects compared with dihydropyridines and therefore cause less reflex tachycardia, making it appealing for treatment of angina,
- Dizziness, headache, redness in the face
- Fluid buildup in the legs and ankle edema
- Rapid heart rate
- Slow heart rate
- Gingival overgrowth
Angiotensin II receptor antagonist
- are a group of pharmaceuticals that modulate the renin–angiotensin system
- Angiotensin II receptor blockers are used primarily for the treatment
of hypertension where the patient is intolerant of ACE inhibitor therapy
- They do not inhibit the breakdown
of bradykinin or other kinins, and are thus only rarely associated with the persistent dry cough and/or angioedema that limit ACE inhibitor therapy.
Mechanism of action
- These substances are AT1-receptor antagonists; that is, they block the activation of angiotensin II AT1 receptors
- Blockage of AT1 receptors directly causes vasodilation, reduces secretion
of vasopressin, and reduces production and secretion of aldosterone
DRUGS WITH AT1 AFFINITY
- Losartan 1000-fold
- Telmisartan 3000-fold
- Irbesartan 8500-fold
- Candesartan greater than 10000-fold
- dizziness, headache, and/or hyperkalemia.