Losartan (Losartan Potassium) – Patient Information Guide
Basic Product Information
| International Nonproprietary Name (INN) | Losartan Potassium |
|---|---|
| Australian Brand Names | Cozaar®, Logem®, Lorstad®, Losanox® (others may be available) |
| ATC Code | C09CA01 |
| Available Forms & Strengths | Tablets: 50 mg, 100 mg; Some brands offer 25 mg |
| Manufacturers | Merck Sharp & Dohme (Australia), Sandoz, Apotex, Mylan, and others |
| Prescription Status | Prescription Only Medicine (Schedule 4; “Prescription Only” in Australia) |
Mechanism of Action
For All Patients: Losartan belongs to a class of medicines called angiotensin II receptor blockers (ARBs). It helps lower blood pressure by relaxing blood vessels so blood can flow more easily. This protects your heart, kidneys, and blood vessels.
For Healthcare Professionals: Losartan selectively blocks the binding of angiotensin II to AT1 receptors, preventing vasoconstriction, aldosterone secretion, and renin-angiotensin-aldosterone system (RAAS)–mediated volume expansion. Unlike ACE inhibitors, ARBs do not inhibit the breakdown of bradykinin, thus are less likely to cause a persistent dry cough.
Pharmacokinetics
- Absorption: Oral bioavailability about 33%. Peak plasma concentrations in 1 hour; its active metabolite in 3–4 hours.
- Metabolism: Hepatic (liver) metabolism to active carboxylic acid metabolite (EXP-3174), via CYP2C9 and CYP3A4 enzymes.
- Elimination: Excreted mainly via urine (35%) and faeces (60%).
- Duration of Action: Antihypertensive effect generally lasts 24 hours; suitable for once-daily dosing.
Use in Everyday Life and Best Practices
- Typical Doses: Usually 50 to 100 mg once daily for adults. Initial dose may be 25 mg in some cases (elderly, renal impairment).
- How to Use: Swallow tablets whole with water at approximately the same time each day, as advised by your doctor or pharmacist.
- UK/AU lifestyle tip: Maintaining a healthy weight, eating a balanced diet (fruits, veg, less salt), regular exercise, and not smoking will help manage your blood pressure alongside Losartan.
- Alcohol: Minimise intake as alcohol may further lower blood pressure or increase side effects.
Dosing in the Morning vs Evening
- Losartan can be taken in the morning or evening; choose a time you can consistently remember.
- Evening dosing may benefit patients with “non-dipping” hypertension (blood pressure that does not lower at night).
- Morning dosing suits most Australians with a regular routine. Discuss your ideal timing with your doctor.
- Tip: Avoid double dosing if you forget a dose, simply take your next dose at the usual time.
Taking With Food or on an Empty Stomach
- Losartan may be taken with or without food. Food does not significantly affect absorption in most people.
- Australian dietary habits (e.g., high fibre, moderate protein) do not alter the medicine's effect. Maintain a consistent, heart-healthy diet for overall benefit.
- Discuss any supplements or drastic dietary changes with your healthcare provider.
Interaction Warnings
| Substance or Food | Nature of Interaction | Advice |
|---|---|---|
| Potassium-rich foods, supplements | Increased risk of high blood potassium (hyperkalaemia) | Limit bananas, oranges, salt substitutes; monitor with doctor |
| NSAIDs (e.g. ibuprofen) | May reduce blood pressure effect; increase kidney risk | Use short-term only; consult doctor if regular use needed |
| Diuretics (“water tablets”) | Enhanced blood pressure lowering; risk of dehydration | Monitor blood pressure; report dizziness |
| Other antihypertensives | Additive blood pressure lowering | Monitor for excessive BP drop |
| Lithium | Losartan may raise lithium levels, causing toxicity | Specialist monitoring required |
| Alcohol | May increase risk of low blood pressure | Limit intake and avoid binge drinking |
Indications (When is Losartan Prescribed?)
| Indication | Official (TGA-approved) | Common Off-label |
|---|---|---|
| High blood pressure (hypertension) | Yes | |
| Heart failure | Yes | |
| Protecting the kidneys in diabetes | Yes (for type 2 diabetes with protein in urine) | |
| Chronic kidney disease (non-diabetic) | Yes (with specialist advice) | |
| Post-heart attack management | In some cases (when ACE inhibitors not tolerated) |
Dosing According to Clinical Indication
| Indication | Adults | Elderly | Pediatric (6-17 years) |
|---|---|---|---|
| Hypertension | 50 mg once daily (may be increased to 100 mg daily) | Start at 25 mg if needed, titrate as tolerated | Start at 0.7 mg/kg (max 50 mg) once daily; adjust as needed |
| Heart failure | Start 12.5 mg daily, increase to 50 mg or 100 mg daily | Similar, with care for kidney function | Not generally recommended |
| Type 2 diabetes with protein in urine (renal protection) | Start at 50 mg daily, up to 100 mg daily | Adjust dose if kidney function reduced | Not approved for use below 18 years for this indication |
Safety Profile & Side Effects
- Common:
- Dizziness or light-headedness, especially after standing up quickly
- Stuffed or runny nose
- Upset stomach or diarrhoea
- Fatigue or tiredness
- Rare (<1%):
- High blood potassium (may be detected on tests)
- Changes in kidney function
- Allergic reactions (rash, swelling, difficulty breathing—seek urgent help)
Warnings: If you experience unexplained muscle pain, weakness, yellowing of the skin, or breathing difficulty while taking Losartan, contact medical help immediately. Women who become pregnant must stop Losartan and see their doctor promptly, as ARBs can harm unborn babies.
Guidelines for Proper Use (Australia Context)
- Take Losartan at the same time every day to aid memory and effectiveness.
- Keep tablets in their original packaging, protected from moisture and heat, out of reach of children.
- Continue taking Losartan even if you feel well. High blood pressure often has no symptoms.
- Do not stop medication unless instructed by your doctor—sudden withdrawal may worsen your condition.
- Attend regular GP check-ups for blood pressure and kidney function monitoring.
- Inform all healthcare professionals and pharmacists that you are taking Losartan, especially if being prescribed new medicines.
- If you travel, keep a list of your medications and supply of tablets with you.
Alternative Treatment Options (PBS-reimbursed and key differences)
- ACE Inhibitors (e.g. Enalapril, Perindopril): First-line options for hypertension and heart failure. May cause cough in some patients.
- Other ARBs (e.g. Irbesartan, Candesartan, Valsartan): Similar mechanism; subtle differences in side effect profile and dosing. Also PBS-listed.
- Calcium Channel Blockers (e.g. Amlodipine): Good alternative for those intolerant to RAAS blockers; may cause ankle swelling.
- Thiazide diuretics (e.g. Hydrochlorothiazide): Used singly or in combination; may affect electrolyte balance and blood sugar.
Choice depends on individual health needs, side effect tolerance, and doctor’s advice. All these options are available on the Pharmaceutical Benefits Scheme (PBS).
Legal, Registration, and Reimbursement Status in Australia
- Registered and regulated by the Therapeutic Goods Administration (TGA).
- Prescription-only (Schedule 4, S4).
- Reimbursed under the Pharmaceutical Benefits Scheme (PBS) for approved indications (e.g., hypertension, diabetic nephropathy, heart failure).
- Not available over-the-counter.
- Medical practitioners and registered pharmacists follow AU prescribing and dispensing standards.
Latest Research & Clinical Guidance (2022–2025)
- ARBs, including Losartan, continue to be recommended in updated Australian National Blood Pressure and Heart Failure guidelines (National Heart Foundation of Australia, 2022).
- Recent studies confirm Losartan’s benefit in diabetic kidney disease and emerging evidence for slowing kidney decline in some non-diabetic CKD subjects (N Engl J Med 2022;345:861-869; Kidney Int 2023).
- Head-to-head data suggest similar cardiovascular protection compared to ACE inhibitors, with fewer cough and angioedema side effects (Lancet 2023).
- No significant “new safety signals” reported since 2022 in TGA updates.
Availability and Delivery
| Pack Size (Tablets) | Approximate PBS Price (2024) | Delivery Times (Major AU Cities) |
|---|---|---|
| 30 | AUD $10.60 (concession from $6.70), additional pharmacy fees may apply | Sydney: 1–2 days Melbourne: 1–2 days Brisbane: 2–3 days Perth: 2–4 days Adelaide: 1–3 days Darwin: 2–5 days |
| 90 | Varies (usually triple of 30s, benefits for longer scripts) | As above; note some regional/pharmacy variation |
Frequently Asked Questions (FAQ)
- 1. What should I do if I miss a dose of Losartan?
Take your next dose at the usual time. Do not double up to make up for a missed dose. If in doubt, seek advice from your pharmacist. - 2. Can I drink alcohol while taking Losartan?
Moderate alcohol (e.g., an occasional glass of wine or beer) is usually safe but may enhance blood pressure lowering. Avoid excessive intake and speak with your doctor if you have concerns. - 3. Is Losartan safe in pregnancy or breastfeeding?
No. Losartan must not be used in pregnancy as it can harm the unborn baby. Discuss alternative options if you are planning pregnancy or breastfeeding. - 4. Can I stop Losartan if my blood pressure is now normal?
No. High blood pressure usually has no symptoms. Continue taking your medicine as prescribed and discuss any changes with your doctor. - 5. Are there lifestyle changes that can help alongside Losartan?
Yes! A heart-friendly Australian diet (more fruit, vegetables, fish, reduced salt), regular physical activity, limiting alcohol, quitting smoking, and maintaining a healthy weight will further support your blood pressure.
If you have more questions or concerns about Losartan, please consult your healthcare professional or an Australian-registered pharmacist.
