Wednesday, April 4, 2012

ANTIHYPERTENSIVES



CENTRAL  ALPHA2 AGONISTS

·         Stimulates alpha receptors in the CNS to inhibit vasoconstriction and reduce peripheral resistance
·         Indication:
o    Hypertension
·         Contraindication:
o    Liver disorders

Example:
clonidine (Catapres®)
guanabenz (Wytensin®)
methyldopa (Aldomet®)
guanfacine (Tenex®)

Side Effects:

·         Dry mouth
·         Drowsiness, dizziness
·         Constipation
·         Tiredness
·         Headache
·         Nervousness
·         Decreased sexual ability
·         Upset stomach
·         Vomiting
·         Rash
·         Fainting
·         Edema of the ankles or feet
·         (+) Coombs test with methyldopa (Aldomet®)

Nursing Considerations:

ü  Monitor vital signs.
ü  Monitor liver function studies.
ü  Provide patient teaching:
o    Instruct patient to avoid abrupt withdrawal (can cause rebound hypertension).
o    Use of clonidine patch (applied once every 7 days):

§  Clean a hairless area of unbroken skin on upper arm or chest with mild soap and water and dry it completely.
§  Peel the clear plastic strip from the adhesive side of a patch.
§  Attach the patch skin by placing the adhesive side against it and pressing firmly. Place an overlay patch provided with prescription over the top of the patch to secure it.
§  If the patch loosens before replacement time, place adhesive tape or an overlay patch to secure it.
§  If the skin under the patch becomes irritated, remove the patch and replace it with a new one in a different area.
§  Fold the used patch in half with the sticky sides together and dispose of it carefully. The patch still contains active medication that could be harmful to children or pets. Always be sure to remove the old patch before applying another one.

ACE INHIBITORS (Angiotensin Antagonists)

·         Inhibits the formation of angiotensin II (vasoconstrictor) and blocks the release of aldosterone.
·         Indication:
o    Used primarily to treat hypertension
o    Also effective in treating heart failure
·         Contraindication:
o    Avoid using with potassium supplements and potassium sparing diuretics
o    Avoid use during the 2nd & 3rd trimester of pregnancy

Example:
benazepril (Lotensin®)
captopril (Capoten®)
enalapril (Vasotec®)
fosinopril (Monopril®)
lisinopril (Prinivil®, Zestril®)
quinapril (Accupril®)
ramipril (Altace®)
moexipril (Univasc®)
perindopril (Aceon®)
trandolapril (Mavik®)

Side Effects:

·         Constant or irritating cough
·         Nausea and vomiting
·         Diarrhea
·         Headache, dizziness
·         Fatigue
·         Insomnia
·         Hyperkalemia
·         Tachycardia
·         First dose hypotension
Nursing Considerations:

ü  Monitor renal function (BUN, creatinine, protein).
ü  Monitor blood glucose levels. Watch for hypoglycemic reactions in patients with DM.
ü  Report bruising, petechiae, bleeding (adverse reaction to captopril)
ü  If patient has experience angioedema with use of ACE inhibitor, do not administer.
ü  Provide patient teachings:
o    Instruct patient not to abruptly discontinue use of captopril (rebound hypertension can occur).
o    Instruct patient to rise slowly after first dose
o    Inform the patient not to take OTC drugs.
o    Teach patient how to take blood pressure.
o    Provide information about side effects.

ANGIOTENSIN II RECEPTOR ANTAGONISTS (ARB)

·         Lower BP by blocking the vasoconstrictive effects of angiotensin II
·         Indication:
o    Used alone or in combination with other agents (ex. Diuretic) for treatment of hypertension.
·         Contraindication:
o    Pregnancy (2nd & 3rd trimester), breastfeeding, renal disoders, hyperkalemia, anuria, hypersensitivity to sulfa drugs


Example:
       losartan (Cozaar®)
       iosartan HCTZ (Hyzar®)
      valsartan (Diovan®)
      eprosartan (Tevetan®)
       irbesartan (Avapro®)
       olmesartan medoxomil (Benicar®)
       telmisartan (Micardis®)

Side Effects:

·         Headache
·         Fatigue
·         Cough, tickling in the throat
·         Angioedema
·         GI reactions
·         Increased serum potassium
·         Transient increase in BUN and creatinine levels

Nursing Considerations:

ü  Obtain baseline BP, PR and rhythm. Monitor regularly.
ü  Monitor the patient for adverse effects.
ü  Monitor patient’s weight, fluid and electrolyte levels.
ü  If given once daily, administer in the morning to prevent insomnia.
ü  Prevent or minimize orthostatic hypotension by assisting the patient to get up slowly. Inform the patient not to make sudden movements.
ü  Maintain sodium restriction, calorie reduction, stress management and exercise program.
ü  Periodic eye examinations are recommended.
  

DIURETICS

Thiazide Diuretics

·         Depress the ability of the convulated tubules to reabsorb sodium and chloride.
·         Indication:
o    Hypertension, edema (CHF)
·         Contraindication:
o    Allergy to sulfa drugs, gout, hypotension, renal failure, lithium therapy, hypokalemia
o    May worsen diabetes


Example:
       chlorothiazide (Diuril®)
       hydrochlorothiazide (HydroDiuril®)
       chlorthalidone (Hygroton®)
      indapamide (Lozol®)
       metolazone (Zaroxolyn®)


Side Effects:

·         Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypercalcemia, hyperurecemia, hypomagnesemia)
·         Decrease in glucose tolerance
·         Increase in LDL cholesterol and triglycerides
·         Hypotension
·         Anorexia
·         Epigastric distress
·         Photosensitivity
·         Sexual dysfunction

Nursing Considerations:

ü  Monitor for side effects of electrolyte imbalance: (muscle weakness, leg cramps, dizziness, abdominal distention, cardiac dysrhythmias)
ü  Provide patient teaching:
o    Thiazides should be taken in the morning to avoid interference with sleep patterns.
o    Take with food if GI distress occurs.
o    Weigh self every morning and report weight gain of more than 2 to 3 lbs.
o    Instruct to eat foods high in potassium (oranges, bananas, broccoli, tomato juice, apricots)
o    Avoid alcohol and black licorice (may precipitate hypokalemia).
o    Thiazides increase lithium toxicity due to loss of sodium.

Loop (High Ceiling) Diuretics

·         Inhibit reabsorption of sodium and chloride in the proximal and distal tubules in the loop of Henle
·         Indication:
o    Potent diuretic for significant diuresis with edema
·         Contraindication:
o    Presence of severe electrolyte imbalances, hypovolemia, anuria, hhypersensitivity to sulfonamides, hepatic coma

Example:
       bumetanide (Bumex®)
       ethacrynic acid (Edecrin®)
       furosemide (Lasix®)
      torsemide (Demadex®)


Side Effects:

·         Fluid and electrolyte imbalances (hypokalemia, hyponatremia, hypocalcemia, hypomagnesemia, hypochloremia)
·         Orthostatic hypotension
·         Thrombocytopenia
·         Skin disturbances, photosensitivity
·         Transient deafness/ ototoxicity (especially with ethacrynic acid)
·         Thiamine deficiency with prolonged use

Nursing Considerations:

ü  Explain that this type of drug is very fast acting.
ü  Monitor for side effects of electrolyte imbalance.
ü  Provide patient teaching:
o    Take loop diuretics in the morning.
o    Take with food or milk.
o    Avoid orthostasis.
o    Use sunscreen for increased photosensitivity.
o    Take potassium supplements as ordered.
o    Weigh self daily and report weight gain of more than 2 or 3 lbs.

Osmotic Diuretics:  

·         Increase osmotic pressure of the glomerular filtrate, inhibiting reabsorption of water and electrolytes
·         Indication:
o    Prevention of renal failure, to decrease ICP, to decrease IOP in narrow-angle glaucoma, used with chemotherapy, oliguria
·         Contraindication:
o    Well established anuria due to renal disease, frank pulmonary edema, cerebral edema, severe dehydration, progressive heart failure or pulmonary congestion after institution of mannitol therapy

Example:

mannitol (Osmitrol®)
Urea (Ureaphil®)
        Not used for diuretic actions.
       See ophthalmic meds.
Glycerin (Osmoglyn®)
Isosorbide (Ismotic®)

Side Effects:

·         Fluid and electrolyte imbalances
·         Pulmonary edema
·         Nausea and vomiting
·         Tachycardia
·         Dehydration

Nursing Considerations:

ü  Monitor the following:
o    Patient’s vital signs
o    Weight
o    Urine output
o    Electrolyte levels
o    Lungs and heart sounds for edema
o    Neurological status
ü  Serum osmolality may be ordered prior to administer
ü  Use filter to administer
ü  Change the patient’s position slowly to prevent orthostatic hypotension.
ü  Do not administer medication if crystallization is noted in the vial.

Carbonic Anhydrase Inhibitors

·         Inhibit the action of the enzyme carbonic anhydrase; decrease availability of hydrogen ions in the kidney, blocking sodium- hydrogen exchange mechanisms, thus increasing urinary excretion of sodium, potassium, bicarbonate and water
·         Indication:
o    Promote diuresis, treat glaucoma, epilepsy and acute mountain sickness
·         Contraindication:
o    Decreased sodium and potassium levels, hepatic and renal disease, severe pulmonary obstruction, adrenocortical insufficiency, patients with drug-induced edema or heart failure (may cause metabolic acidosis), chronic noncongestive angle-closure glaucoma, hypersensitivity to sulfonamides

Example:
 cetazolamide (Diamox®)
metazolomide (Neptazine®,GlaucTabs®)
dichlophenamide (Daranide®)

Side Effects:

·         Fatigue, malaise
·         Drowsiness
·         Headache
·         Orthostatic hypotension
·         Paresthesia
·         Urticaria
·         Pruritus
·         Stevens-Johnson syndrome
·         Photosensitivity
·         Hypokalemia, other electrolyte imbalances
·         Metabolic acidosis

Nursing Considerations:

ü  Administer drug with food if GI upset occurs.
ü  Provide patient teaching. Advise patient to avoid prolonged or unprotected exposure to sunlight during therapy.

Potassium-Sparing Diuretics

·         Act directly on the distal tubule of the kidney to increase excretion of sodium, water, chloride, calcium ions; decrease excretion of potassium and hydrogen ions
·         Indication:
o    Hypertension, edema, heart failure, cirrhosis, nephrotic syndrome, diuretic-induced hypokalemia
·         Contraindication:
o    Severe renal and hepatic disease, hyperkalemia
o    Use with caution in patients with DM

Example:
amiloride (Midamor®)
amiloride HCL and hydrochlorothiazide (Moduretic®)
spinorolactone (Aldactone®)
spinorolactone and hydrochlorothiazide (Aldactazide®)
triamterene (Dyrenium®)


Side Effects:

·         Abdominal pain or cramps
·         Anorexia
·         Diarrhea
·         Constipation
·         Acidosis
·         Nausea and vomiting
·         Agranulocytosis
·         Blood volume depletion
·         Sore throat, dry mouth
·         Dizziness
·         hyperkalemia
·         Orthostatic hypotension Megaloblastic anemia (with triamterene)
·         Impotence, gynecomastia and menstrual abnormalities (Spinorolactone)
Nursing Considerations:

ü  Monitor the patient for signs and symptoms of hyperkalemia (confusion, hyperexcitability, muscle weakness, paresthesia, flaccid paralysis, arrhythmias, abdominal distention, diarrhea, intestinal colic). Monitor for other electrolyte imbalances.
ü  Weigh the patient daily.
ü  Assess the patient for dehydration.
ü  Administer potassium-sparing diuretics with care if patient is also taking other medications that can increase potassium.
ü  Give potassium-sparing diuretic in the morning to avoid nocturia.
ü  Give amiloride with food.
ü  Avoid salt substitutes and foods rich in potassium.
ü  Store spironolactone in a light-resistant container. 

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