What is the introduction of Antihypertensive drugs
Antihypertensive are a class drug that are used to treat
hypertension.
These drugs act by reducing the cardiac output or reducing the total
peripheral resistance.
Hypertension :- A persistence elevation of blood pressure is more than 140/90 mmHg is called hypertension.
Or
Hypertension is a disorder characterized by pressure on blood vessels wall
increase more than 140mmHg systolic and more than 90mmHg diastolic.
What is the Definition of Antihypertensive drugs
The drugs use in the treatment of hypertension, are called antihypertensive
Drug.
Classification / list of hypertensive drug
(1) Diuretics :-
(A) Thiazides
- Hydrochlorothiazide
- Chlorthalidone
- Indapamide
(B)High ceiling
- Furosemide
- Bumetanide
(C) k+ Sparing
- Spironolactone
- Amiloride
Mnemonics (Trick) :- HCI - F - SA
(2) ACE Inhibitors :-
- Captopril
- Enalapril
- Lisinopril
- Perindopril
- Ramipril
- Fosinopril
Mnemonics (Trick) :- RAM KI LEP CF HE
(3) Angiotensin ( AT¹ , receptor) Blockers :-
- Losartan
- Candesartan
- Irbesartan
- Valsartan
- Telmisartan
Mnemonics (Trick) :- I LV CT
(4) Calcium channel blockers :-
- Verapamil
- Diltiazem
- Nifedipine
- Felodipine
- Amlodipine
- Nitrendipine
- Lacidipine
(5) β Adrenergic blockers :-
- Propranolol
- Metoprolol
- Atenolol
Mnemonics (Trick) :- MAP
(6) β + α Adrenergic blockers :-
- Labetalol
- Carvedilol
(7) α¹ Adrenergic blockers :-
- Prazosin
- Terazosin
- Doxazosin
- Phentolamine
- Phenoxybenzamine
(8) Central sympatholytics :-
- Clonidine
- Methyldopa
(9) Vasodilator :-
(A) Arteriolar
- Hydralazine
- Minoxidil
- Diazoxide
Mnemonics (Trick) :- HY MINOXI DI
(B) Arteriolar+venous
- Sodium nitroprusside
(1) Diuretics :-
Diuretics are the drugs which increases the rate and volume of the urine
formation.
These drugs mainly act on nephron and increase excretion of excessive
fluid.
Uses of diuretics
- Edema
- Hypertension
- Drug poisoning
- Liver cirrhosis
- Kidney disease
Advantage of diuretics
- Hyperkalemia
- Metabolic acidosis
- Hyperglycemia
- Hyperuricemia
- CNS disturbance
- Allergic reaction
- Gastrointestinal upset
- Nausea and vomiting
- Diarrhoea
(A) Thiazides :-
The thiazides is a type of molecule and class of diuretics often used to treat
hypertension and edema.
They act as decrease the rate of glomerular filtration by producing nagetive
sodium balance.
Mechanism of action of Thiazides
Thiazides act on the early distal tube of nephron and is a first line drug
that use to treat hypertension.
This group of drugs block sodium (Na+) and chloride (Cl) symporter systems in
early distal tubule.
They also inhibit carbonic hydrase activity and increase bicarbonate
loss.
Thiazides also enhance excretion of magnesium (mg+) and potassium (k+) but
they inhibit urinary excretion of calcium and uric acid resulting in
hypercalcemia and hyperuricemia.
Uses of Thiazides
- Hypertension
- Congestive heart failure
- Edema
- Renal stone (By calcium excretion)
- Diabetes insipidus (By reduce plasma volume and GFR)
Adverse effects of Thiazides
- Hypokalemia ( Hypokalemia is the most important side effect of thiazides)
- Metabolic alkalosis
- Hypovolemia ( Due to excessive fluid loss)
- Hypotension
- Dehydration (Due to increase urine out put)
- Hyponatremia (Due to decrease Na+ level)
- Hyperglycemia
- Weakness
- Fatigue
(B) High Celling (loop) Diuretics :-
Loop diuretics act on the ascending lymph of the loop of henle.
They are high effications as diuretics.
Frusemide
Frusemide is the most commonly used diuretics and sulfonamide
derivative.
It can be taken by injection into vein and by mouth.
Frusemide effect is decrease with metolazone.
Dose of frusemide
- 2mg/kg body weight in children.
- 20 to 80 mg/day IV in adult.
Brand name of frusemide
The brand name of frusemide is laxis that is available in both tablet and
injection form.
Mechanism of action of frusemide
Frusemide is a loop diuretics which reduce the absorption of electrolytes in
the thick ascending limb of henle loop.
It is greatly increase the excretion of sodium and chloride in the
urine.
Frusemide is a weak carbonic an hydrase inhibitor. It increase the excretion
of bicarbonate and phosphate.
Pharmacokinetics
Frusemide is rapidly absorbed orally highly ,bound to plasma protein,
metabolize in the liver and excreted by the kidney.
Plasma half time is 2 hours and duration of action is 4 - 6 hours.
Uses of High Celling (loop) Diuretics
- Edema
- Acute renal failure (loop diuretics enhance the urine out put and potassium excretion)
- Acute pulmonary edema
- Cerebral edema
- Hypertension
- Acute hypercalcemia
Adverse effects of loop Diuretics
- Hypokalemia
- Metabolic alkalosis
- Hyponatremia
- Hypovolemia
- Hypotension
- Hypocalcemia
- Auto toxicity
- Hyperglycemia
- Hyperlipidemia
(C) k+ sparing :-
K+ sparing diuretics are medication that increase urination without the loss
of k+.
Mechanism of action of k+ sparing
K+ sparing acts from interstitial side of the distal tube and collecting duct
and combind with aldosterone receptor and inhibit the action of
aldosterone.
It has no effect on Na+ and k+ transport in the absence of aldosterone while
under circumstances, it increase Na+ excretion and decrease k+
excretion.
Uses of k+ sparing drugs
- Edema
- Hypertension
- Congestive heart failure
Adverse effect of k+ sparing drugs
- Gynecomastia (enlarge breast tissue in mene or boys)
- Drowsiness
- Hyperkalemia
- Metabolic acidosis
- Skin rashes
(2) ACE inhibitors :-
ACE inhibitors is the class of antihypertensive drugs used in the treatment of
hypertension and congestive heart failure.
This group of drugs causes relaxation of blood vessels as well as decrease
blood volume which lead to lower blood pressure.
Mechanism of action of ACE inhibitors
This class of drugs inhibit the angiotensin converting enzyme and
prevent formation of ACE - 2.
Pharmacokinetics
ACE inhibitors are generally well absorb and excrete from kidney.
The plasma half life of ACE inhibitors drugs is 2 hour.
Uses of ACE inhibitor
- Hypertension
- Congestive heart failure
- Chronic renal failure
Adverse effect of ACE inhibitor
- Hypotension
- Hyperkalemia
- Skin rashes
- Teratogenicity
(3) Angiotensin blocker :-
Angiotensin receptor blocker also known as angiotensin (AT1) receptor
antagonists or sartans are a group of antihypertensive drugs.
Angiotensin receptor blocker are use for hypertension.
Mechanism of action of angiotensin blocker
Angiotensin receptor blocker act by blocking angiotensin receptor which
control physiological effect of angiotensin on blood pressure and water.
Uses of angiotensin receptor blocker
- Diabetes
- Myocardial infraction
- Congestive heart failure
- Hypertension
Adverse effect of angiotensin receptor blocker
- Hypotension
- Hyperkalemia
(4) Calsium channel blocker :-
These are the another group of antihypertensive drugs.
It is a type of medication that people take to increase the flow of blood pressure and oxygen to the heart.
Calsium channel blocker also known as calsium antagonists.
Mechanism of action of calsium channel blocker
Ca+ channel blocker block the entry of ca+ into muscle cells which lead to
muscle relaxation and cause dilation of arteries and reduce blood
pressure.
Uses of calsium channel blocker
- Case oh hypertension emergency
- Also use in pregnancy induced hypertension
- Also used in renal impairment
- Heart arrhythmia
- Cluster headache
Adverse effect of calsium channel blocker
- Headache
- Flushing
- Edema
(5) β (beta) - blocker :-
It is act on beta - 1 or beta - 2 andregenic receptor by blocking activity of
receptor.
It cause membrane stabilization which leads to smooth muscle relaxation and
muscle relaxation circulatory system.
Most appropriate type of beta blocker is beta - 2 receptor blocker because it
is a selective beta - 1 blocker may act on respiratory system and cause
complication.
Use of β (beta) - blocker
- Hypertension
- Angio pectoris
- Myocardial infraction
- Tachycardia
- Anxiety
- Portal hypertension
- Migrane
Adverse effect of β (beta) - blocker
- Bradycardia
- Congestive heart failure
- Fatigue
(6) α¹ (alpha) Adrenergic blockers :-
Alpha receptor antagonist block them adrenergic response mediated through
adrenergic receptor.
Mechanism of action of α¹ Adrenergic blockers
It act on α¹ (alpha) Adrenergic receptor and blocked , result in decrease
norepinephrine which leads to vasodilation and decrease blood pressure.
Uses of α¹ (alpha) Adrenergic blocker
- Hypertension
- Pheochromocytoma
- Benign prostatic hyperplasia
- Raynaud syndrome
Adverse effect of α¹ (alpha) Adrenergic
- Postural hypotension
- Palpitation
- Dizziness
- Drowsiness
- Fatigue
- Weakness
(7) Central sympatholytics :-
Sympatholytics drugs may be used into interfere with sympathetic overactivity
at different level including centrally at ganglia, neurons and receptor.
Mechanism of action of Central sympatholytics
Antiadrenergic agents act on the vasomotor center. It stimulates the alpha - 2
adrenergic receptor and decrease sympathetic out flow results in fall in blood pressure and bradycardia.
Uses of Central sympatholytics
- Hypertension
- Opioid with drowaly alcohol withdrawal
- Smoking cessation
- Diabetic nephropathy
Adverse effect of Central sympatholytics
- Sedation
- Distrub sleep
- Bradycardia
- Postural hypertension
(7) Vasodilator :-
Vasodilator release the vascular smooth muscle result in decrease blood
pressure due to decrease peripheral vascular resistance.
Hydralazine
It is a medication use to treat high blood pressure.
Hydralazine is called vasodilator.
It works by relaxing blood vessels so blood cam flow through the body more
easily.
Mechanism of action of hydralazine
This medication directly acting smooth muscle relaxant and act as a
vasodilator. It cause decrease in blood pressure which associated with
tachycardia.
Pharmacokinetics
It is may absorb orally and bioavalability is higher.
Uses of hydralazine
- Angina pectoris
- Myocardial infraction
- Severe hypertension
- Hypertension into pregnancy
Adverse effect of hydralazine
- Dizziness
- Drowsiness
- Edema
- Flushing
- Palpitation
- Water retention
Minoxidil
Minoxidil is a medication use for the hypertension treatment and it is also
use for the treatment of male pattern hair loss.
Mechanism of action of minoxidil
It directly act on arterioles by opening k+ channel into smooth muscle causing
hyperpolarization of the cell membranes.
Uses of minoxidil
It is very potent vasodilator which use in hypertension when other drugs
fails.
Adverse effect of minoxidil
Same as hydralazine
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What is the drug of choice for hypertension
The drug of choice and best drug for hypertension is thiazides diuretics
(reduce all morbidity and mortality rates in adults person with moderate to
severe hypertension) and ACE inhibitors, calsium channel blocker.
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