Losartan

# Losartan ## Overview - **Classification**: Angiotensin Receptor Blocker (ARB) - **Mechanism**: Selectively blocks angiotensin II type 1 (AT1) receptors, preventing vasoconstriction and aldosterone secretion. ## Primary Indications 1. **Hypertension**: Treatment of high blood pressure. 2. **Diabetic Nephropathy**: To slow progression in type 2 diabetes and hypertension. 3. **Stroke Risk Reduction**: For patients with hypertension and left ventricular hypertrophy (LVH). ## Adult Dosing ### Standard Dosing **Hypertension** - **Dose**: Initial **25 mg** or **50 mg** - **Frequency**: Once daily - **Route**: Oral - **Maximum Dose**: **100 mg** once daily. **Diabetic Nephropathy (Type 2 Diabetes & HTN)** - **Dose**: Initial **50 mg** - **Frequency**: Once daily - **Route**: Oral - **Maximum Dose**: May be increased to **100 mg** once daily based on BP response. **Stroke Risk Reduction (HTN & LVH)** - **Dose**: Initial **50 mg** - **Frequency**: Once daily - **Route**: Oral - **Maximum Dose**: Up to **100 mg** once daily (may add HCTZ). ### Dose Adjustments - **Renal Impairment**: No initial dose adjustment for mild-moderate. - Consider lower starting dose (**25 mg** once daily) for severe impairment (CrCl <30 mL/min) or on dialysis. - **Hepatic Impairment**: Initial dose **25 mg** once daily. - Increased systemic exposure. - **Elderly Patients**: No initial dose adjustment needed. - Consider **25 mg** once daily if volume-depleted or on diuretics. ## Pediatric Dosing ### Neonates (0-28 days) - **Dose**: Not recommended. - **Special Notes**: Safety and efficacy not established. Risk of renal adverse effects. ### Infants (1-12 months) - **Dose**: Not generally recommended. - **Special Notes**: Limited data, safety and efficacy not established. Close monitoring if used off-label. ### Children (1-12 years) - **Indication**: Hypertension (off-label, but commonly used) - **Dose**: Initial **0.7 mg/kg** - **Frequency**: Once daily - **Maximum**: Do not exceed **50 mg** once daily initially. - **Special Notes**: May be increased to **1.4 mg/kg** daily (max **100 mg**). Use oral suspension for precise dosing. ### Adolescents (13-18 years) - **Indication**: Hypertension - **Dose**: Initial **25 mg** to **50 mg** - **Frequency**: Once daily - **Maximum**: **100 mg** once daily. - **Special Notes**: Dosing similar to adults, start at lower end of range. ## Safety Information ### Contraindications - **Absolute**: Pregnancy (especially 2nd and 3rd trimesters) due to fetal toxicity. - **Absolute**: Concomitant use with aliskiren in patients with diabetes or renal impairment (CrCl <60 mL/min). - **Absolute**: Hypersensitivity to losartan or any component. - **Relative**: Bilateral renal artery stenosis (risk of acute renal failure). ### Common Adverse Effects - **Common (1-10%)**: Dizziness, upper respiratory infection, nasal congestion, back pain, fatigue, diarrhea. - **Less Common (0.1-1%)**: Hyperkalemia, cough (lower incidence than ACEIs). - **Serious but Rare**: Angioedema, severe hypotension, acute renal failure, rhabdomyolysis. ### Key Drug Interactions - **Potassium-sparing diuretics/Potassium supplements**: Increased risk of **hyperkalemia**. Monitor serum potassium. - **NSAIDs (e.g., ibuprofen, naproxen)**: May reduce hypotensive effect and increase risk of **renal dysfunction**, especially in elderly/dehydrated. Monitor BP and renal function. - **Lithium**: May increase lithium levels, leading to **lithium toxicity**. Monitor lithium levels closely. - **Aliskiren**: Increased risk of **hypotension, hyperkalemia, and renal impairment**. Avoid in diabetes/renal impairment. ## Monitoring & Follow-up - **Before Treatment**: Baseline BP, renal function (SCr, BUN), serum electrolytes (potassium). - **During Treatment**: BP regularly (e.g., within 1-2 weeks of initiation/dose change). - Renal function and electrolytes periodically (e.g., 1-2 times/year or more frequently if unstable). - **Clinical Signs**: Watch for signs of angioedema, severe dizziness/fainting (hypotension), muscle weakness (hyperkalemia). ## Clinical Pearls - 💡 **Tip 1**: Losartan is a suitable alternative for patients experiencing ACE-inhibitor induced cough. - 💡 **Tip 2**: Administer once daily. Can be taken with or without food. - 💡 **Tip 3**: Counsel patients to avoid potassium supplements or salt substitutes without medical advice due to hyperkalemia risk. - 💡 **Tip 4**: Females of child-bearing potential must be counseled on the importance of contraception due to fetal harm. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.