Hyzaar (Losartan / Hydrochlorothiazide)

Hyzaar (Losartan / Hydrochlorothiazide) – Patient Information

Basic Product Information

Mechanism of Action

For Patients

Hyzaar contains two ingredients to help lower blood pressure. Losartan relaxes your blood vessels by blocking a hormone (angiotensin II) that tightens them. Hydrochlorothiazide helps your body get rid of extra salt and water through urine, which reduces the amount of fluid your heart needs to pump. Together, these effects lower your blood pressure and reduce strain on your heart.

For Specialists

Losartan is a selective AT1 receptor antagonist, decreasing angiotensin-II-mediated vasoconstriction, aldosterone secretion, and sympathetic activation. Hydrochlorothiazide, a thiazide diuretic, inhibits sodium reabsorption in the distal convoluted tubule, promoting natriuresis and reducing plasma volume.

Pharmacokinetics

• Absorption: Losartan ~33%, Hydrochlorothiazide ~65–75% oral bioavailability.
• Metabolism: Losartan is metabolised in the liver (CYP2C9, CYP3A4) to the active form E-3174. Hydrochlorothiazide is not significantly metabolised.
• Elimination: Losartan: mainly via urine and bile. Hydrochlorothiazide: unchanged in urine.
• Half-life: Losartan: 2 hours; active metabolite: 6–9 hours. Hydrochlorothiazide: 6–15 hours.
• Duration of action: Most antihypertensive effect lasts 24 hours with once-daily dosing.

Use in Everyday Life and Best Practices

Hyzaar is commonly prescribed in Australia to manage high blood pressure (hypertension), reducing the risk of stroke, heart attack, and kidney problems. It is also used when blood pressure is not controlled with a single medicine. Always take Hyzaar exactly as directed by your doctor or pharmacist.

• Tablets are taken once daily, usually at the same time each day for best results.
• Do not stop taking Hyzaar suddenly without advice — this can increase your risk of complications.
• Regular blood pressure monitoring is important to track your response.

Dosing: Morning vs Evening

• Morning dosing: Preferred, as hydrochlorothiazide may increase urination; reduces nighttime bathroom trips.
• Evening dosing: May be considered if recommended by your doctor, but could disrupt sleep due to increased urination.
• Tip: Take at a time that helps you remember, such as with breakfast.

Taking with Food or on an Empty Stomach

• Hyzaar can be taken with or without food.
• Food does not affect how well the medicine is absorbed.
• For some patients, taking it with a meal reduces stomach upset.
• Typical English dietary habits (such as a light breakfast or tea) do not impact efficacy.

Interaction Warnings

Indications

Dosing According to Clinical Indications

Safety Profile and Side Effects

Most people tolerate Hyzaar well, but like all medicines, it can cause side effects. Regular monitoring may be needed, particularly for your kidneys and electrolytes (salt balance).

Guidelines for Proper Use

1. Take Hyzaar exactly as prescribed; do not skip or double up on doses if you miss a tablet.
2. Keep hydrated but follow your doctor’s advice on how much fluid to drink.
3. Attend regular check-ups for blood pressure and blood tests.
4. Report any unusual symptoms (persistent cough, swelling, chest pain) promptly.
5. Store Hyzaar in a cool, dry place out of reach of children.

Alternative Treatment Options

• Combination therapy with perindopril/indapamide, amlodipine/valsartan: May be considered if intolerant to losartan/thiazide.
• Single-agent Angiotensin Receptor Blockers (ARBs): Good for mild hypertension, but often less effective alone.
• Calcium channel blockers (amlodipine): Well-tolerated, but can cause ankle swelling.
• ACE inhibitors (perindopril, ramipril): As effective, but risk of cough/angioedema in some patients.
• Thiazide diuretics alone (hydrochlorothiazide, indapamide): Used in specific settings or if ARB not tolerated.
• The above options are commonly reimbursed by the PBS (Pharmaceutical Benefits Scheme) in Australia for hypertension management.

Hyzaar's advantages: Fixed-dose combination improves convenience and adherence, reduces pill burden, and improves blood pressure control; however, not suitable for all patients (e.g., those with severe kidney impairment or pregnancy).

Legal, Registration, and Reimbursement Status in Australia

• Hyzaar is a Schedule 4 (S4) medication: only available with a prescription.
• Registered with the Therapeutic Goods Administration (TGA) under the ARTG (Australian Register of Therapeutic Goods).
• Reimbursed under the Pharmaceutical Benefits Scheme (PBS) for approved uses (hypertension, risk reduction post-LVH).
• Not available for purchase 'over the counter'.

Latest Research and Clinical Guidance (2022–2025)

• Recent guidelines from the National Heart Foundation of Australia (NHFA) recommend combination antihypertensive therapy (like Hyzaar) early for most Australians not achieving target BP on single therapy (NHFA Guideline 2023).
• Cochrane review (2023) confirms losartan/diuretic combination offers superior BP control with similar side effect profile compared to monotherapy or ACEi/diuretic.
• ARBs such as losartan show lower risk of cough/angioedema than ACE inhibitors (NICE, 2022).
• Continued recommendation for routine kidney function and electrolytes monitoring while on any diuretic therapy (Australian Medicine Handbook, 2024).

Availability and Delivery

Frequently Asked Questions (FAQ)

1. Do I need to take Hyzaar at the same time every day?
   Yes. Taking Hyzaar at the same time each day helps maintain steady blood levels and makes it easier to remember.
2. Can I drink alcohol while taking Hyzaar?
   Moderation is key. Alcohol can increase the risk of low blood pressure and dizziness. Discuss your usual drinking habits with your doctor or pharmacist.
3. How long will I need to be on Hyzaar?
   Hypertension is usually a long-term condition. Many patients need ongoing medication to maintain target blood pressure and reduce long-term health risks.
4. What should I do if I miss a dose?
   If you miss a dose, take it as soon as you remember. If it’s almost time for your next dose, skip the missed dose. Do not take two doses at once.
5. Is Hyzaar safe in pregnancy or breastfeeding?
   No. Hyzaar should not be used during pregnancy or breastfeeding. Inform your doctor immediately if you become pregnant.

For further information or specific advice, please consult your doctor, practice nurse or community pharmacist.