How losartan works
As a representative of the so-called AT1 inhibitors (“sartans”), losartan blocks the docking sites of the messenger substance angiotensin II on the blood vessel walls. As a result, the vasoconstrictor messenger can no longer transmit its effect – the blood vessels dilate and the blood pressure slowly drops.
Sartans such as losartan also suppress the undesirable structural remodeling of the heart and kidney tissue as a result of overactivation of the renin-angiotensin-aldosterone system (RAAS). Like the so-called ACE inhibitors, they are therefore standard medication after a heart attack, in cases of cardiac insufficiency and chronic kidney dysfunction.
With the RAAS, the body has a sophisticated system for regulating blood pressure: if it needs more energy, blood pressure is automatically increased. During resting phases, on the other hand, it is regulated downwards. If this system is disrupted, this can lead to increased blood pressure. Those affected usually don’t notice it and it gradually gets worse.
The small vessels in particular, such as those found in the eye and kidneys, are damaged by the constantly increased pressure. If high blood pressure remains undetected and untreated for a long time, it can have serious consequences such as loss of vision and kidney dysfunction.
Absorption, breakdown and excretion
After absorption by mouth (orally), the active substance is only partially absorbed from the intestine into the blood. After distribution in the organism, it is then broken down in the liver. Among other things, this produces a degradation product that still has a blood pressure-lowering effect.
Approximately two hours after ingestion (seven hours for the breakdown product), half of the active ingredient has been broken down. The degradation products are excreted via the kidneys.
When is losartan used?
The areas of application (indications) for losartan include
- High blood pressure (hypertension)
- Kidney disease in patients with hypertension or type 2 diabetes
- Chronic heart failure (chronic cardiac insufficiency)
- Reduction of the risk of stroke in patients with hypertension and left ventricular hypertrophy (enlargement of the left ventricle)
How losartan is used
The active substance is usually administered in the form of tablets. Due to its rapid breakdown in the body, it may be necessary to take losartan twice a day. This ensures a consistent effect. However, once daily administration is often sufficient.
The usual dosage is between 12.5 and 100 milligrams per day and should not exceed 150 milligrams. Children, adolescents and patients with kidney dysfunction are given a reduced dose.
What are the side effects of losartan?
Occasionally (in less than one percent of those treated), gastrointestinal complaints and heart palpitations occur as a result of taking the drug.
The side effects can be very well limited by close monitoring of therapy by the doctor.
What should be considered when taking losartan?
Contraindications
Losartan must not be taken if:
- hypersensitivity to the active substance or any of the other ingredients of the medication
- severe liver dysfunction
- concomitant use of aliskiren (blood pressure medication) in patients with type 2 diabetes or impaired kidney function
- Pregnancy in the 2nd or 3rd trimester (third trimester)
Interactions
Taking losartan at the same time as other medications can lead to interactions. Certain medications can increase the blood pressure-lowering effect of losartan. These include, among others:
- other antihypertensive drugs (antihypertensives)
- tricyclic antidepressants (such as amitriptyline or imipramine)
Certain painkillers (such as ibuprofen, acetylsalicylic acid) can reduce the effect of losartan. This interaction must be taken into account, particularly in patients with renal dysfunction. If taken at the same time, it can lead to a further deterioration in kidney function.
Losartan can increase the blood level of potassium – especially if it is used in combination with certain other drugs. These include, for example, potassium-sparing diuretics (such as spironolactone, triamterene) and other medicines that can increase potassium levels (such as heparin and trimethoprim).
Ability to drive and operate machinery
As dizziness and circulatory problems may occur after taking the medicine, attention should be paid to the individual’s ability to react, especially at the start of treatment. Patients should then decide together with their doctor whether they can continue to actively participate in road traffic or operate heavy machinery.
Age restriction
The active ingredient is already approved in Germany and Austria for children from the age of six. They receive a reduced dose that is adapted to their body weight.
In Switzerland, the use of losartan in children and adolescents under the age of 18 is not recommended according to the prescribing information.
Pregnancy and breastfeeding
Like all sartans, losartan is contraindicated in the second and third trimester of pregnancy, as drugs in this group can lead to fetal disorders.
How to obtain medication with losartan
Medicines containing losartan are only available on prescription in Germany, Austria and Switzerland.
How long has losartan been known?
In 1995, the active ingredient losartan was approved in the USA as a treatment for high blood pressure. It was the first representative of the so-called AT1 inhibitors.
Losartan counteracts high blood pressure just as well as the popular ACE inhibitors (captopril, enalapril, ramipril, lisinopril). However, these often cause an irritating cough as a side effect, which is not the case with losartan and other sartans.
