Indapamide Tablets: Types, Doses, and Differences (IR vs SR and Combos)

You clicked this because you want something simple: what types of indapamide tablets exist, how they differ, and which one might fit your situation. Here’s the short, honest answer-there are two main solo versions (immediate‑release and sustained‑release) plus popular combo tablets with an ACE inhibitor. They’re not interchangeable milligram for milligram, they behave differently in your body, and the choice affects side effects, lab checks, and day‑to‑day routines.

Set your expectations: you’ll get a clear map of the tablets available in Australia in 2025, practical rules for starting and switching, and checklists you can use before your next GP or pharmacist chat. No fluff. Just what matters.

• TL;DR: Two solo types-Immediate‑release 2.5 mg (IR) and Sustained‑release 1.5 mg (SR, often called Natrilix SR)-plus fixed‑dose combos with perindopril.
• IR and SR are not mg‑equivalent. 1.5 mg SR roughly matches the BP effect of 2.5 mg IR but don’t swap without prescriber guidance.
• SR is once daily with smoother levels; IR can cause a quicker peak. SR tablets must not be crushed or split.
• Both are PBS‑listed (2025) for essential hypertension in Australia; combo tablets may reduce pill burden.
• Check electrolytes and kidney function at baseline, at 1-2 weeks after starting or switching, then periodically.

Types at a glance: IR, SR, and combination tablets

When people say indapamide tablets, they usually mean one of three families you’ll see on a script in Australia:

• Immediate‑release (IR) indapamide 2.5 mg
• Sustained‑release (SR) indapamide 1.5 mg (often branded Natrilix SR)
• Fixed‑dose combinations, typically perindopril/indapamide in different strengths

All of them are thiazide‑like diuretics used mainly for high blood pressure. They help your kidneys let go of extra salt and water and also relax blood vessels a bit. The differences are in the release profile, dose, and how steady the drug level is in your bloodstream.

Immediate‑release (IR) 2.5 mg: As the name says, this version dissolves and absorbs relatively quickly. You get a faster peak, then it tails off. It’s usually taken once each morning. Many IR tablets are scored and can be split; check the specific brand leaflet. IR is useful when your prescriber wants a clear on/off effect or needs stepwise titration.

Sustained‑release (SR) 1.5 mg (also called controlled‑release or MR): This is designed to release the drug slowly across the day. The dose looks smaller, but the exposure is steadier, which helps blood pressure control and may reduce swings that can cause dizziness. These tablets are film‑coated and must not be crushed or split. In Australia, Natrilix SR 1.5 mg is the classic brand; there are PBS‑listed generics too.

Fixed‑dose combinations (FDCs): If you see perindopril/indapamide on your box, that’s a combo tablet-common pairs include 5 mg/1.25 mg or 10 mg/2.5 mg (perindopril arginine with indapamide). Doctors choose these when two medicines are needed and you want fewer pills. The indapamide component in combos is typically immediate‑release, and the dosing is once daily.

Here’s a quick side‑by‑side to make the practical differences obvious:

Are IR and SR “the same”? In clinic, the blood‑pressure effect of 1.5 mg SR is often similar to 2.5 mg IR, but they’re not interchangeable milligram for milligram. The release curve differs, and that changes how you feel across the day. Don’t swap without your prescriber planning the switch and checking labs.

Australian context check (2025): both IR 2.5 mg and SR 1.5 mg are PBS‑listed for essential hypertension. Fixed‑dose perindopril/indapamide combinations are also PBS‑listed in various strengths. Always confirm brand‑specific excipients-some tablets contain lactose; the Consumer Medicine Information (CMI) or pharmacist can confirm.

Evidence backbone: This summary aligns with the Australian Medicines Handbook 2025, TGA Product Information for indapamide IR 2.5 mg and Natrilix SR 1.5 mg, and guideline advice from RACGP/Australian hypertension guidance (2023 update), NICE CKS Hypertension (2023), and ESC/ESH Hypertension Guidelines (2023). Those sources consistently treat indapamide as a thiazide‑like diuretic option for first‑line or add‑on therapy, with attention to electrolytes and kidney function.

How to choose, take, and switch safely

Choosing between IR, SR, or a combo is less about brand names and more about fit. Think about steadiness of effect, your routine, other meds, and monitoring. Here’s a clean, practical way to decide and use indapamide well.

Quick decision rules (use with your prescriber):

• If you want a smoother effect with fewer peaks: consider 1.5 mg SR.
• If you need flexible dose adjustments or you’re titrating from scratch: start with 2.5 mg IR.
• If you already take perindopril and need a diuretic: a perindopril/indapamide combo can simplify things.
• If you have a history of dizziness or big BP swings: SR often suits better.
• If adherence is shaky: once‑daily SR or a single combo pill helps.

Before you start (5‑minute checklist):

• Baseline labs: sodium, potassium, creatinine/eGFR, and uric acid if you have gout.
• Medication review: ACE inhibitors/ARBs, lithium, digoxin, NSAIDs, steroids, laxatives-these can interact with diuretics or worsen electrolyte shifts.
• Medical flags: dehydration risk, low‑salt diet, vomiting/diarrhoea, past hyponatraemia, severe renal impairment.
• Lifestyle: day shift vs night shift; bathroom access in the morning (diuresis is mild with indapamide compared with loop diuretics, but it’s still real).
• Allergies: indapamide is a sulfonamide derivative-true severe sulfonamide allergy is rare but worth discussing.

How to take it (simple rules):

1. Take once each morning at the same time. Food isn’t essential, but a consistent routine helps.
2. SR 1.5 mg: swallow whole-no crushing, chewing, or splitting.
3. IR 2.5 mg: can often be split if scored; confirm your brand’s CMI or ask your pharmacist.
4. Stay hydrated, especially in hot weather. If you develop vomiting, diarrhoea, or fevers, follow “sick day” rules: pause the tablet and call your GP or pharmacist for advice.
5. Sun sense: use sunscreen and cover up; photosensitivity reactions can happen, though uncommon.

Monitoring that actually catches trouble:

• Blood pressure: home BP checks in the morning and evening for the first 1-2 weeks. Keep a log.
• Labs: check sodium, potassium, and creatinine/eGFR 1-2 weeks after starting or changing dose/type, then at 3 months, then every 6-12 months (closer if older, on multiple diuretics, or on ACEi/ARB).
• Symptoms to watch: dizziness on standing, cramps, palpitations, confusion, excessive thirst, or very low urine output-call your doctor.

Switching safely (IR ↔ SR):

• IR 2.5 mg to SR 1.5 mg: most people do a simple next‑day swap without overlap. Treat it as a therapeutic equivalent switch, not mg‑for‑mg identical. Recheck electrolytes and creatinine in 1-2 weeks.
• SR 1.5 mg to IR 2.5 mg: again, next‑day switch is standard. Expect a quicker peak; take it in the morning. Monitor BP and labs.
• From solo to perindopril/indapamide FDC: only switch if you already tolerate both agents. Choose a combo strength that matches your established doses.

What about kidney function?

Thiazide‑like diuretics such as indapamide still lower blood pressure even when eGFR trends down, but diuretic “power” fades in severe renal impairment. Labels and the Australian Medicines Handbook 2025 advise caution and close monitoring in moderate‑to‑severe kidney disease. Your prescriber may prefer a different agent or add a loop diuretic if fluid retention is a big issue. Always individualise.

Common side effects-and what to do:

• Dizziness or light‑headedness, especially early on: check your home BP; if it’s very low (e.g., under 100/60 and you feel unwell), hold the dose and call your GP.
• Low potassium (cramps, weakness) or low sodium (headache, confusion): needs a blood test; it’s not guesswork.
• Gout flare: indapamide can raise uric acid. If you’ve had gout, mention it upfront.
• Rash or sun‑sensitivity: stop and seek medical advice.
• Very rare but serious: pancreatitis (severe upper abdominal pain)-urgent care.

Two real‑world scenarios (to make it concrete):

• “I get woozy by mid‑morning on 2.5 mg IR.” Solution: talk to your GP about switching to 1.5 mg SR for a flatter profile. Plan a lab check 1-2 weeks later.
• “I’m on perindopril 5 mg and my BP’s still up.” If you tolerate perindopril and your labs are fine, your GP might add indapamide IR 2.5 mg or move to a perindopril/indapamide 5/1.25 mg combo to keep it to one pill.

Interactions worth knowing (no scare‑mongering, just the hits):

• ACE inhibitors/ARBs: good partners, but watch for an early BP drop and electrolyte shifts-check labs after changes.
• Lithium: diuretics can raise lithium levels-often a no‑go unless you have tight specialist monitoring.
• Digoxin: low potassium increases digoxin toxicity risk-monitor potassium closely.
• NSAIDs (e.g., ibuprofen): can blunt BP‑lowering and strain kidneys-limit use and keep your GP in the loop.
• Steroids or laxative overuse: can worsen low potassium.

Special situations:

• Pregnancy: diuretics, including indapamide, aren’t first‑line for high BP in pregnancy-speak with your obstetric team.
• Breastfeeding: indapamide passes into milk; most references advise avoiding-confirm with your doctor or pharmacist.
• Sports anti‑doping: diuretics are prohibited by WADA; if you’re a tested athlete, you need to discuss a Therapeutic Use Exemption (TUE).

Checklists, comparisons, and quick answers

Here’s the practical toolkit-things you can act on today.

Which type is “best” for you?

• Pick SR 1.5 mg if you’ve had dizziness with peaks or you value a smoother, once‑daily routine and you don’t need tablet splitting.
• Pick IR 2.5 mg if you need titration flexibility or you might split tablets under pharmacist advice.
• Pick a perindopril/indapamide combo if you’re already on both drugs separately and want fewer pills.

Red‑flag symptoms (don’t wait on these):

• Fainting, confusion, severe weakness, or new palpitations
• Severe tummy pain (possible pancreatitis)
• Very low BP readings with symptoms

Mini‑FAQ

Can I take indapamide at night? You can, but morning is standard to match your daily rhythm and reduce night‑time bathroom trips. If night dosing works better for shift work, discuss it with your GP and stick to the same time each day.

Is 1.5 mg SR weaker than 2.5 mg IR? On paper the mg is lower, but the SR gives a steadier exposure. In practice, many people see similar BP lowering. They’re not mg‑equivalent though, so treat a switch as a change that needs monitoring.

Can I crush or split SR tablets? No. That breaks the slow‑release design. If swallowing tablets is hard, ask about IR formulations or other options; a liquid is not routinely available in Australia.

Will I pee all day? Indapamide is milder than loop diuretics like furosemide. You may notice a slight uptick in morning urination, especially on IR, but most people find it manageable.

What about weight and cholesterol? Indapamide is considered metabolically friendlier than some older diuretics. Still, electrolytes need checking. This view is reflected in AMH 2025 and international guidelines.

Can I drink alcohol? Moderation is key. Alcohol can worsen dizziness and drop your BP. If you feel light‑headed after a drink, ease back or skip it.

Is it okay with diabetes? Usually, yes-monitor glucose as usual. Indapamide has a lighter metabolic footprint than some alternatives but always watch labs.

How soon will my BP improve? Many people see a change within a week. Full effect can take 2-4 weeks. Keep logging your readings.

Do I need salt substitutes? Not without advice. Some substitutes contain potassium; that’s not always suitable. Focus on a normal‑to‑lower salt diet, not zero‑salt, and ask your clinician before using substitutes.

Execution checklists you can use

Start‑day checklist (print this):

• I know whether my tablet is IR 2.5 mg, SR 1.5 mg, or a combo.
• I know if I can split it (IR maybe yes; SR no).
• I’ve had baseline labs or have a plan to get them this week.
• I know when to recheck labs (in 1-2 weeks).
• I have a home BP plan (morning/evening readings for 1-2 weeks).

Two‑week review checklist:

• Any dizziness, cramps, or headaches?
• BP trend improving toward target (often under 130-140 systolic depending on your plan)?
• Lab results: sodium, potassium, creatinine/eGFR stable?
• Any new meds (e.g., NSAIDs) since starting indapamide?

Ongoing (every 3-6 months):

• Repeat labs and BP log.
• Skin check for rashes; reinforce sun protection.
• Review need for a combo pill if you’re on more than one BP agent.

Pitfalls to avoid

• Crushing SR tablets-don’t.
• Swapping IR↔SR without telling your GP or arranging labs.
• Starting an NSAID daily (like ibuprofen) without a plan for monitoring-can undo BP control and stress kidneys.
• “Powering through” vomiting/diarrhoea-follow sick‑day rules and call for advice.

Pro tips from the clinic

• If mornings are chaotic, link the dose to a fixed cue (phone alarm, brushing teeth). Adherence beats perfection.
• On SR but still dizzy? Check you’re not also restricting fluids heavily; review other meds that drop BP.
• If you need perindopril plus indapamide, moving to a combo can reduce forgotten doses-but only after you tolerate both separately.

Next steps / Troubleshooting

• New to indapamide, BP high, no other meds: Start IR 2.5 mg or SR 1.5 mg with baseline labs; recheck in 1-2 weeks; adjust based on BP and electrolytes.
• On IR, feel peaks and dips: Discuss switching to SR 1.5 mg; plan a lab check in 1-2 weeks and track symptoms.
• Already on perindopril with good tolerance: Consider a perindopril/indapamide combo to simplify dosing; match established strengths.
• eGFR trending down: Stay on top of labs; consider alternative or adjunct strategies with your GP (sometimes a loop diuretic if fluid retention dominates).
• Endurance athlete under testing: Diuretics are banned. Talk to your sports doctor about TUE pathways before starting.

Credible sources used to shape this guide: Australian Medicines Handbook 2025; TGA Product Information for indapamide IR 2.5 mg and Natrilix SR 1.5 mg; RACGP and Australian hypertension guidance (2023 update); NICE CKS Hypertension (2023); ESC/ESH Hypertension Guidelines (2023). These are the yardsticks clinicians in Australia lean on for dosing, monitoring, and safety.

If you only remember three things: know your tablet type (IR, SR, or combo), don’t switch formulations casually, and book that 1-2 week lab check after any change. That’s how you keep the benefits and dodge the avoidable headaches.