Losartan: Drug study and nursing interventions

GENERAL DESCRIPTION

Losartan belongs to angiotensin receptor blockers. It is very potent drug and given orally. Losartan is well tolerated in patients with heart failure than other ARBs

GENERIC NAME: Losartan

BRAND NAME: Cozaar

MECHANISM OF ACTION

Captopril is angiotensin II receptor blocker. It competitively blocks the AT₁ receptor where angiotensin II is attached and initiates its biological actions. This blockage directly causes vasodilation, reduce secretion and production of vasopressin and aldosterone. These actions reduce blood pressure.

PHARMACOKINETICS

It is given orally. The metabolite of Losartan is more potent than losartan. It is metabolized by CYP3A4 and CYP2C9 system. Peak plasma level is approximately 1 – 3 hours after oral administration. Half-life of its metabolite is 2.5 hours and losartan is 6-9 hours. Protein binding of Losartan is 98%. Plasma clearance is hepatic and kidney clearance with 90%/10% respectively

INDICATIONS

• Hypertension
• Stroke prophylaxis
• Heart failure in elderly patients

CONTRAINDICATIONS

• Hepatic failure (Plasma clearance of losartan decrease)
• Pregnancy (Teratogenic effect)

SIDE EFFECTS & ADVERSE EFFECTS

• Hypotension
• Oliguria
• Progressive azotemia
• Acute renal failure
• Hyperkalemia (patient with renal disease)
• Anaphylaxis
• Abnormal hepatic function
• Neutropenia
• Leukopenia

DRUG INTERACTION

• Losartan enhance antihypertensive effects of other antihypertensive agents
• Indometacin reduce hypotensive effects of Losartan
• Mannitol induced acute renal failure when given with Losartan
• Rifampicin increase metabolism of Losartan and its active metabolite thus reduce the antihypertensive effects of Losartan
• Potassium supplements or potassium rich diets can cause cardiac arrhythmias and hyperkalemia when given with losartan
• Losartan increase the toxicity of Lithium when given concurrently
• Losartan when given with insulins can enhance the hypoglycemic effects
• K-sparing diuretics can cause hyperkalemia when given with Losartan
• Aspirin and NSAIDS may reduce the hypotensive effects of Losartan
• Beta blockers enhance the hypotensive effects of Losartan when given concurrently

NURSING INTERVENTION

• Avoid given first dose at night due to increase hypotensive risk.
• Monitor blood pressure and pulse frequently.
• Enquire the complete health history of patient specially any renal disease
• Check patient s/s for angioedema.
• Monitor electrolytes specially sodium and potassium levels, uric acid levels and CBC

PATIENT EDUCATION

• Avoid potassium rich diet and supplements when taken losartan
• Do not breast feed when taken losartan
• Inform patients the s/s of hypotension.
• Inform HP about pregnancy if conceived.
• Take plenty of water to avoid dehydration.