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Antihypertensive drug (Diuretic (for chronic treatment (thiazide diuretics…

- - - - dietary restriction of Na shows decrease in BP in hypertensive patients
  - - - but after 6-8 weeks the CO becomes normal while PVR declines
  - - - indapamide
        
        non-thiazide sulfonamide diuretic with vasodilator effect
      - hydrochlorothiazide
        clopamide
      - Side effects
        
        Can cause potassium depletion, Mg depletion, impair glucose tolerance, increase uric acid conc.
    - - Na+ channel antagonists
        amiloride
        triamterene
      - aldosterone antagonists
        spirolactone
  - - - furosemide
        ethacrynic acid
- - - - over 140/90 mmHg
    - - over 160/100 mmHg
    - - over 180/110 mmHg
  - - - Idiopathi
      - Caused by combination of diseases
        
        Genetic
        
        Environment
        
        Diet
    - - Renal artery constriction
      - Coarctation of the aorta
      - Pheochromozytoma
      - Cushing disease
      - Primary hyperaldosteronism
- - - - nitrendipine
        nifedipine
        nicardipine
        amlodipine
        felodipine
        isradipine
        nimodipine
        nisoldipine
        lacidipine
      - Short acting
      - used only for chronic treatment as an sustained release preparation
      - The oral short acting is only used in emergency cases of severe hypertension
      - relative selectivity to vascular smooth muscle
      - used for mild and moderate hypertension / prinzmetal angina
      - side effects
        
        transient reflex tachycardia
        
        dizziness
        
        flushing
        
        peripheral edema
  - - - prodrug
        
        minoxidil sulphate is activated form by hepatic sulphotransferase
      - MOA
        
        minoxidil sulphate activates ATP modulated K+ channel -> opening of K+ channel in smooth muscle cell -> hyperpolarization -> relax
      - side effect
        
        Fluid and salt retention
        
        cardiovascular effects
        
        Increased CO
        
        Baroreflex
        
        Hair growth
        
        Hypertrichosis
      - Used in cases where other anti-hypertensive drugs failed in severe hypertension.
    - - exclusively arteriolar effect
      - Only I.V treatment for severe hypertension
        
        effect within 3-5 min
      - side effect
        
        Salt and water retention
        
        Hyperglycemia
  - - - it is a complex of iron with cyanide group ans a nitroso moiety
        
        rapidly metabolized with liberation of cyanide
      - cyanide
        
        less toxic thiocyanate
      - eliminated by the kidney
      - if patient is defective in cyanide metabolism -> intoxication
      - MOA
        
        result is increased IC cGMP level -> relaxes vascular smooth muscle
        
        activation of guanylyl cyclase either via release of NO or direct stimulation of the enzyme
      - sodium nitroprusside is sensitive to light -> the bottle is covered with foil
  - - - fall in sodium concentration of the fluid in the distal tubule
      - fall in renal perfusion pressure
      - β1 receptor stimulation
      - prostacyclin
    - - angiotensin2 (as feedback mechanism)
      - atrial natriuretic peptide
      - angiotensinogen & antgiotensin1 (as feedback mechanism)
- - - - α-methyl-NA also formed in noradrenergic neurons of vasomotor center
        
        anti-hypertensive effect by diminishing vasomotor center activity
        
        reduces tone of the vasomotor center in CNS
      - competitive inhibition of NE production
        
        α2 receptor agonist
        
        as false substrate, α-methyldopa is converted into α-methyl-NA
      - similar to DOPA in chemical structure
      - old fashion drug for treatment of hypertension in pregnancy (safe)
        
        peripheral effect
        
        agonist of adrenergic receptor -> not responsible for antihypertensive effects
        
        central effect
        
        stimulation of central α2 receptor agonist action -> negative feedback -> antihypertensive effects
      - Side effect
        
        Sedation
        
        Impaired mental concentration
        
        Depression
        
        Vertigo
        
        Increased prolactin secretion
    - - They are Imidazoline derivatives
      - can bind to imidazoline receptors on presynpatic membranes
      - Clonidine is lipid-soluble
        
        can enter the brain rapidly from the circulation
        
        available as tablet or transdermal
      - MOA
        
        centrally acting Alpha 2 adrenoceptor agonist
      - Its function is inhibition of NA release
      - Medical use
        
        Good for hypertension
      - Side effect
        
        dry mouth and sedetaion
    - - new imidazoline derivatives -> only bind to imidazoline receptor
      - function
        
        inhibition of noradrenaline releasing
      - Medical use
        
        good for hypertension
  - - - phentolamine
        
        short acting reversible drug
        
        action on α1-receptor
        
        it block α1 causing vasodilation
        
        BP decrease
        
        but this gives baroreflex
        
        increases heart rate (tachycardia is side effect)
        
        action on α2 receptor
        
        it inhibit α2 receptor causing stimulate high NA secretion (α2 is feedback)
        
        so, it can cause tachycardia as side effect
        
        used as anti-hypertensive drug but not used anymore because of side effects
        
        side effects
        
        tachycardia (due to baroreflex + α2 blockage)
        
        posture hypotension
        
        because α blocker cause venodilation
      - Phenoxybenzamine
        
        binds covalently to α1 and α2 receptor
        
        irreversible binding (T1/2 is 24hr)
        
        termination of effects is done by new receptor synthesis
        
        for pheochromocytoma
    - - Only in vessels
      - Prazosin
        
        remarkable first pass->Æ need high oral dose / T1/2 is 3-4hr
      - doxazosin, terazosin
        
        longer lasting effect
      - Common side effect
        
        Postural hypotension
        
        reflex tachy
    - - Decrease CO. Inhibit cathecolamine stimulated reninrelease
      - Side effects of Beta-2 antagonism
        
        Asthma
        
        hypoglacemia
      - Propanolol
        
        inhibition of β1
        
        useful to reduce work of heart
        
        inhibition of β2
        
        not useful
        
        in that it can constrict vessel / bronchus and cause hyperglycemia
      - remarkable first pass
        
        Need high dose
    - - oxprenolol
        pindolol
        acebutolol
        penbutolol
        
        partial agonist is not antagonist
        
        but it can occupy β-receptor
        
        inhibiting the binding of NA or N
        
        recommended for elderly people
        
        it just cause mild negative heart effect
    - - metoprolol (betaloc)
        atenolol
        betaxolol
        bisoprolol
        nebivolol
        celiprolo
        
        metoprolol is mother compound
        
        other drugs have longer T1/2
    - - labetalol
        
        non-selective -> acts on α+ β blockers
        
        used for
        
        pheochromocytoma
        
        hypertensive crisis