Losartan is a prescription medication used to manage high blood pressure (hypertension). It belongs to a class of drugs called Angiotensin II Receptor Blockers (ARBs). ARBs work by preventing a hormone from binding to receptors that cause blood vessels to narrow. This action allows blood vessels to relax and widen, lowering the pressure within the arteries.
Losartan’s Standard Dosing Schedule
Losartan is most commonly prescribed for once-daily administration. The typical starting dose for adults with hypertension is 50 milligrams, though a lower 25-milligram dose may be used for patients taking diuretics or who have other medical conditions. This single-dose schedule is possible because the drug is converted into a potent, long-acting form after ingestion.
The parent drug, Losartan, has a relatively short half-life of about one and a half to two and a half hours. Approximately 14% of the drug is metabolized in the liver into an active compound known as E-3174. This active metabolite is significantly more powerful, often cited as 10 to 40 times more potent than Losartan itself.
The active metabolite E-3174 has a much longer terminal half-life, ranging from six to nine hours. This extended presence provides the sustained pharmacological effect needed to regulate blood pressure for a full 24-hour period from a single dose. If a once-daily dose is not sufficient to control blood pressure, the standard procedure is to increase the total amount taken, typically up to a maximum of 100 milligrams once daily.
When Twice-Daily Dosing May Be Necessary
While once-daily dosing is the norm, a healthcare provider may split the total daily dose into two separate administrations (twice-daily or BID dosing). This strategy optimizes effectiveness when the patient is already taking the maximum daily dose of 100 milligrams. Splitting the dose means dividing the total amount, such as 50 milligrams in the morning and 50 milligrams in the evening, without exceeding 100 milligrams total per day.
One reason for this change is to counteract the “end-of-dose phenomenon,” where blood pressure begins to rise shortly before the next scheduled dose. Splitting the total daily dose aims to achieve a smoother, more even concentration of the active metabolite in the bloodstream. This provides more consistent 24-hour blood pressure control and is relevant for individuals with resistant hypertension where standard once-daily dosing is inadequate.
Twice-daily administration can also manage specific side effects. If a patient experiences transient effects, such as dizziness or a sudden drop in blood pressure (hypotension) shortly after taking the pill, splitting the dose may mitigate the peak drug concentration in the blood. This reduces the intensity of these effects. Patients should never initiate a twice-daily schedule without the explicit direction of their prescribing physician, who must assess the individual’s blood pressure response and overall health profile.
Consistency and Safety in Losartan Management
Consistency is fundamental to managing hypertension with Losartan, regardless of the dosing frequency. It is recommended to take the medication at the same time each day to maintain steady levels of the drug and its active metabolite. This adherence ensures continuous therapeutic benefit and prevents unwanted fluctuations in blood pressure.
If a dose is missed, the general procedure is to take it as soon as it is remembered. If it is close to the time for the next scheduled dose, the missed dose should be skipped entirely, and the patient should resume their normal schedule. Never take two doses at once to compensate for a missed one, as this increases the risk of side effects, including excessively low blood pressure.
Patients taking Losartan should be monitored regularly by their healthcare team, especially when a dosage or frequency change occurs. Monitoring involves checking for signs of low blood pressure and assessing kidney function and potassium levels, as the drug can affect these parameters. These checks ensure the medication is working safely and effectively.