Losartan Potassium and Hydrochlorothiazide Tablets (Hyzaar) is a compound antihypertensive drug composed of losartan potassium (an angiotensin II receptor blocker, ARB) and hydrochlorothiazide (a diuretic). It is indicated for the treatment of hypertension and the reduction of stroke risk in patients with hypertension and left ventricular hypertrophy.
How to Use Losartan Potassium and Hydrochlorothiazide Tablets (Hyzaar)
For Hypertension Treatment
Initial Dosage: The recommended starting dose is 50/12.5 mg (50 mg losartan potassium / 12.5 mg hydrochlorothiazide), administered once daily.
If blood pressure is not well controlled, the dose can be gradually increased to the maximum dose of 100/25 mg once daily after 3 weeks.
Switching from Monotherapy
If a patient previously using 50 mg losartan potassium as monotherapy fails to achieve the target blood pressure, they can switch to Hyzaar 50/12.5 mg. If the effect is still insufficient, the dose can be adjusted to 100/25 mg or a combination of two 50/12.5 mg tablets.
If a patient develops hypokalemia while originally using 25 mg hydrochlorothiazide, they can switch to Hyzaar 50/12.5 mg to reduce the risk of electrolyte imbalance.
For Hypertension Complicated with Left Ventricular Hypertrophy
For patients with poor blood pressure control under monotherapy, it is recommended to start with Hyzaar 50/12.5 mg, and gradually adjust the dose to 100/12.5 mg or 100/25 mg. If necessary, combine with other antihypertensive drugs.
It should be noted that Black patients may not obtain the same benefit of stroke risk reduction.
Medication for Special Populations of Losartan Potassium and Hydrochlorothiazide Tablets (Hyzaar)
Pregnant Women
Contraindication: Use in the second and third trimesters of pregnancy can cause fetal renal damage, skull hypoplasia, and even fetal death. Once pregnancy is confirmed, the drug must be discontinued immediately.
Risk Warning: Hydrochlorothiazide can cross the placenta, leading to fetal jaundice or thrombocytopenia, and should be avoided during pregnancy.
Patients with Hepatic or Renal Impairment
Hepatic Impairment
Initial treatment is not recommended because a starting dose of 25 mg cannot be achieved. Patients with severe liver disease require careful dose adjustment.
Renal Impairment
Patients with mild to moderate renal impairment need regular monitoring of renal function and serum potassium to avoid volume depletion-induced acute renal failure.
The safety of this drug in patients with a creatinine clearance of < 30 mL/min has not been established, and its use is contraindicated in such cases.
Elderly Patients
The effectiveness of the drug in elderly patients (≥ 65 years old) is comparable to that in young adults, but the incidence of adverse reactions may be slightly higher. Therefore, closer monitoring of blood pressure and electrolytes is required.
Children and Lactating Women
Children: The effectiveness of this drug in children has not been established, so its use is not recommended.
Lactating Women: It is not clear whether losartan potassium is excreted into human milk, but hydrochlorothiazide can pass into breast milk. It is recommended to weigh the pros and cons and choose to discontinue the drug or stop breastfeeding.
Precautions and Potential Risks of Losartan Potassium and Hydrochlorothiazide Tablets (Hyzaar)
Effects on Electrolytes and Metabolism
Hydrochlorothiazide may cause hypokalemia, hyponatremia, hypomagnesemia, and hyperuricemia, while losartan potassium may cause hyperkalemia. Therefore, regular monitoring of electrolytes is necessary.
Drug Interactions
Potassium-Increasing Drugs: Concurrent use with potassium supplements or potassium-sparing diuretics may cause hyperkalemia.
NSAIDs: Non-steroidal anti-inflammatory drugs (NSAIDs) may reduce the antihypertensive effect and increase the risk of renal damage, so concurrent use should be avoided.
Lithium Preparations: Hydrochlorothiazide can increase the serum lithium concentration, so close monitoring of lithium levels is required when used concurrently.
Other Warnings
Allergic Reactions: Patients allergic to sulfonamide drugs may experience cross-allergic reactions.
Acute Glaucoma: A rare but serious sulfonamide-related reaction may occur, characterized by a sudden decrease in vision. In such cases, the drug must be discontinued immediately and medical attention sought.
