Losartan

Losartan was the first approved AT1 receptor blocker (sartan) and has a special feature: it is the only sartan that also lowers uric acid levels. This makes it particularly suitable for patients with high blood pressure and concurrent gout or elevated uric acid levels.

Losartan is available as a single-ingredient product and in combination with hydrochlorothiazide (Losartan comp.).

Losartan blocks the AT1 receptor:

Mechanism of action:

• Selective blockade of the AT1 receptor
• Prevents the action of angiotensin II
• Widening of the blood vessels and lowering of blood pressure

Special feature – lowering uric acid:

• Losartan inhibits the URAT1 transporter in the kidney
• As a result, more uric acid is excreted in the urine
• The only sartan with this additional effect
• Useful in patients with gout or hyperuricemia

Duration of action: Losartan has a relatively short half-life. The active metabolite EXP3174 prolongs the effect, so taking it once a day is sufficient.

Losartan is suitable for:

• Adults with high blood pressure
• Hypertensive patients with left ventricular hypertrophy (stroke prevention)
• Kidney protection in type 2 diabetes with proteinuria

Especially recommended for:

• High blood pressure and gout/hyperuricemia
• High blood pressure with thickening of the heart
• Diabetic kidney disease

Not suitable:

• Pregnancy and breastfeeding
• Severe hepatic insufficiency
• Concomitant use with aliskiren in diabetes or impaired kidney function (GFR below 60 ml/min/1.73 m²)

High blood pressure:

• Starting dose: 50 mg once daily
• Usual dose: 50-100 mg once daily
• Maximum dose: 100 mg daily

Kidney protection in diabetes:

• Starting dose: 50 mg once daily
• Target dose: 100 mg once daily

Available strengths:

• 12.5 mg, 25 mg, 50 mg, 100 mg tablets

Combination:

• Losartan + hydrochlorothiazide (Losartan comp.)

How to take:

• Once daily, always at the same time of day
• Regardless of meals
• Take with water

Notes:

• Regular blood pressure and laboratory checks
• Adequate fluid intake
• Do not stop abruptly

Special note: If blood pressure is not lowered sufficiently with 100 mg, a combination with HCT or a calcium channel blocker may be more appropriate than increasing the dose.

Losartan must not be taken in cases of:

• Hypersensitivity to losartan
• Pregnancy in the 2nd and 3rd trimester
• Severe hepatic insufficiency
• Concomitant use with aliskiren in diabetes or impaired kidney function (GFR below 60 ml/min/1.73 m²)

Caution in:

• Renal insufficiency
• Renal artery stenosis
• Dehydration
• Aortic or mitral stenosis
• Hyperkalemia

Pregnancy and breastfeeding: Losartan is not recommended in the 1st trimester of pregnancy and is contraindicated in the 2nd and 3rd trimesters. Treatment should not be started during pregnancy. If pregnancy is detected, treatment must be stopped immediately and, if necessary, another therapy started. Losartan is not recommended during breastfeeding.

Common (1-10%):

• Dizziness
• Hyperkalemia
• Fatigue
• Hypotension

Uncommon (0.1-1%):

• Headache
• Sleep disorders
• Gastrointestinal complaints
• Kidney function disorders
• Muscle cramps

Rare:

• Angioedema
• Hepatitis
• Rhabdomyolysis
• Anemia

General: Sartans are very well tolerated. Unlike ACE inhibitors, they do not cause a dry, irritating cough.

Contraindicated:

• Aliskiren in diabetes or renal insufficiency

Caution with:

• Potassium-sparing diuretics → hyperkalemia
• NSAIDs → reduced effect
• Lithium → increased levels
• Rifampicin, fluconazole → altered breakdown of losartan

Note: Losartan is broken down via CYP2C9 and CYP3A4. Medications that inhibit or activate these enzymes can influence its effect.