Nisoldipine
Pronunciation: (nye-SOLE-di-peen).
- Generic name
- nisoldipine
- Brand names
- SULAR (US, brand discontinued, generics remain)
- Drug class
- Calcium Channel Blocker (Dihydropyridine)
- Form
- Extended-release tablet (8.5 mg, 17 mg, 34 mg)
- Route
- Oral
- Legal status
- Prescription only in the United States. Confirmed NOT authorised in Canada. UK, Australia, and New Zealand status could not be independently verified in this pass (see country-brand-verification.json).
Supply Rules Vary
Trade names by country: United States
Australia: · Full directory
What nisoldipine is and how it works
Nisoldipine is a dihydropyridine calcium channel blocker FDA-approved for the treatment of hypertension, used alone or with other antihypertensive medicines. It is not FDA-approved for angina. (1)
Nisoldipine has an unusually low absolute bioavailability (about 5%) and its absorption is dramatically affected by food — it must be taken on an empty stomach. It also has a real, specific interaction with phenytoin that can make nisoldipine ineffective, and the label advises avoiding any medicine known to strongly affect the CYP3A4 liver enzyme.
Mechanism of action: how nisoldipine works
Nisoldipine is a dihydropyridine calcium channel blocker with unusually low absolute bioavailability (~5%) due to extensive first-pass metabolism, >99% protein binding, and a terminal half-life of 13.7 ± 4.3 hours. Peak concentration is reached slowly (~9.2 hours). A high-fat meal increases Cmax by up to 245% and decreases AUC by 25% — the basis for the empty-stomach administration instruction. (1)
What nisoldipine is used for
Hypertension
Nisoldipine extended-release tablets are FDA-approved to treat hypertension, alone or in combination with other antihypertensive agents. (1)
Before taking nisoldipine
Do not take / not appropriate for
- Do not use nisoldipine if you have a known hypersensitivity to nisoldipine or other dihydropyridine calcium channel blockers. (hypersensitivity) (1)
Tell your clinician about
- Every prescription medicine, nonprescription medicine, vitamin, and supplement you currently use — especially phenytoin or anything your clinician or pharmacist identifies as a strong CYP3A4 inhibitor or inducer.
- Any history of heart failure or reduced heart pumping function.
- Any liver disease — dosing needs adjustment.
- If you are pregnant, planning pregnancy, or breastfeeding.
- If you have severe narrowing of the heart's arteries (severe coronary artery disease) — increased angina has been reported.
How to take nisoldipine
- Take nisoldipine on an EMPTY STOMACH — at least 1 hour before or 2 hours after a meal. A high-fat meal can raise peak nisoldipine levels by up to 245% and lower total absorption by 25%, so consistent, empty-stomach dosing matters for how predictably it works.
- Swallow the extended-release tablet whole. Do not crush, chew, or split it.
- The FDA label describes starting at 17 mg once daily, increased by 8.5 mg at intervals of a week or longer to control blood pressure, with a usual maintenance dose of 17-34 mg once daily. Doses above 34 mg/day are not recommended.
- Do not stop taking nisoldipine suddenly without consulting your doctor.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6) (8)
Missed dose
If you miss a dose, contact your prescriber or pharmacist for guidance rather than doubling your next dose.
Overdose
No nisoldipine-specific overdose case data was found in the label reviewed. The label notes that overdose with other dihydropyridine calcium channel blockers has caused pronounced low blood pressure, and describes supportive treatment (cardiovascular/respiratory monitoring, elevating the limbs, careful use of calcium infusion, vasopressors, and fluids). Dialysis is unlikely to help because nisoldipine is highly protein-bound; plasmapheresis may have some benefit. Seek emergency care immediately for a suspected overdose. (1)
Side effects
The two most common side effects — swelling and headache — occurred in roughly 1 in 5 people taking nisoldipine in clinical trials, both more common than with placebo.
Swelling of the ankles or feet (peripheral edema)
What to notice: Occurred in 22% of people on nisoldipine vs. 10% on placebo in clinical trials; it is dose-related.
What to do: Mention it to your clinician, especially if significant or bothersome. (1)
Headache
What to notice: Occurred in 22% of people on nisoldipine vs. 15% on placebo.
What to do: Mention persistent or severe headache to your clinician. (1)
Dizziness or sore throat (pharyngitis)
What to notice: Each occurred in about 5% of people on nisoldipine vs. 4% on placebo.
What to do: Mention persistent or bothersome symptoms to your clinician. (1)
Increased angina in people with severe coronary artery disease
What to notice: New or worsening chest pain occurred in 1.5% of nisoldipine patients vs. 0.9% on placebo, particularly in those with severe underlying coronary disease.
What to do: Contact your clinician promptly for new or worsening chest pain. (1)
Rare serious events
What to notice: Atrial fibrillation, stroke, heart attack, fainting, or a systemic allergic reaction (angioedema) have been reported, though not common.
What to do: Seek prompt or emergency medical assessment for these symptoms. (1)
Serious warnings
Increased angina or heart attack risk in severe coronary artery disease — serious
Symptoms: New or worsening chest pain, particularly in people with severe underlying coronary artery disease.
Action: Contact your prescriber promptly for new or worsening chest pain; seek emergency care for severe or persistent chest pain. (1)
Heart failure caution — serious
Symptoms: Safety in people with heart failure or reduced heart pumping function has not been established.
Action: Your prescriber should weigh this carefully if you have heart failure; report new or worsening shortness of breath, swelling, or fatigue promptly. (1)
Severe hypotension on initiation — serious
Symptoms: Marked blood pressure drop, especially when starting therapy or increasing the dose, particularly in people already on other blood-pressure-lowering medicines.
Action: Your prescriber will monitor blood pressure at initiation and with dose changes. Contact your clinician for severe dizziness or fainting. (1)
Phenytoin interaction — serious
Symptoms: Taking phenytoin together with nisoldipine has been shown to lower nisoldipine to undetectable blood levels — meaning it may stop working.
Action: This combination should be avoided; your prescriber will consider an alternative therapy. (1)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Phenytoin | Coadministration has been shown to lower nisoldipine to undetectable blood levels. | This combination should generally be avoided; your prescriber may choose an alternative therapy. (1) |
| Any known strong CYP3A4 inhibitor or inducer | The label gives a blanket instruction to avoid coadministration with any known inducer or inhibitor of the CYP3A4 liver enzyme, not just specific named drugs. | Tell your prescriber and pharmacist about every medicine and supplement you take so they can screen for this. (1) |
| Grapefruit and grapefruit juice | Significantly increases nisoldipine levels, similar to or more pronounced than with other dihydropyridine calcium channel blockers. | Avoid grapefruit and grapefruit juice entirely during treatment. (1) |
| Cimetidine | Increases nisoldipine levels by about 30-45% (AUC and peak concentration). | Your clinician may monitor more closely or choose an alternative if these are combined. (1) |
| Ranitidine | Decreases nisoldipine total exposure by about 15-20%, not considered clinically significant. | No specific action required based on this finding alone. (1) |
| Beta-blockers, digoxin, warfarin | No clinically significant pharmacokinetic interaction found in the label reviewed. | Still disclose these to your clinician as part of a complete medicine review. (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Hepatic impairment
In people with liver cirrhosis, nisoldipine blood levels were 4 to 5 times higher than in healthy people given the same dose. A starting dose of no more than 8.5 mg daily is recommended for people with impaired liver function. (1)
Renal impairment
No dose adjustment is recommended for mild-to-moderate kidney impairment, based on the label reviewed. (1)
Older adults (over 65)
A starting dose of no more than 8.5 mg daily is recommended, the same caution as for liver impairment. (1)
Pregnancy
The FDA label states nisoldipine should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus. In animal studies, it was neither teratogenic (did not cause birth defects) nor toxic to the fetus at doses that were not toxic to the mother. This label text does not state a specific pregnancy risk category — do not assume one is documented here even though some other general sources describe nisoldipine as 'Pregnancy Category C.' (1)
Breastfeeding — a real, disclosed evidence gap
It is not known whether nisoldipine passes into human breast milk. The NIH's LactMed database states that because no information at all is available on nisoldipine's use during breastfeeding, an alternate drug — nifedipine or nitrendipine — may be preferred. This is a genuine gap in the evidence, not a reassurance either way; discuss it directly with your prescriber and your baby's healthcare provider. (1) (2)
Monitoring
Before starting
- Review liver function, since dosing needs adjustment for hepatic impairment.
- Review all current medicines and supplements — screen specifically for phenytoin and any known strong CYP3A4 inhibitor or inducer.
- Discuss pregnancy, pregnancy plans, and breastfeeding, including the real evidence gap on breastfeeding above.
- Confirm whether you have severe coronary artery disease, since increased-angina risk is specifically documented in that group.
During treatment
- Blood pressure monitoring at initiation and with any dose change.
- Watch for new or worsening chest pain, especially if you have underlying coronary artery disease.
- Watch for swelling, and discuss with your clinician before assuming it is heart failure rather than a known drug effect.
- Keep taking nisoldipine on an empty stomach consistently — inconsistent timing relative to meals can meaningfully change how much drug you absorb.
Storage
Store at 20-25°C (68-77°F), protected from light and moisture.
Study the drug class: Dihydropyridine calcium channel blockers
Professional information
Clinician-facing context only. Use the current US prescribing information and complete medication review. Non-US product, brand, and supply information is limited to what is explicitly documented in country-brand-verification.json and country-supply-classification.json.
United States
Indication: Hypertension only (not FDA-approved for angina)
Dose summary: Initial 17 mg PO once daily; titrate by 8.5 mg at intervals of ≥1 week; usual maintenance 17-34 mg once daily; max 34 mg/day. Elderly (>65) and hepatic impairment: start ≤8.5 mg/day. Must be taken on an empty stomach (1h before or 2h after a meal) — high-fat meal raises Cmax up to 245% and lowers AUC 25%.
Renal context: No dose adjustment needed for mild-to-moderate renal impairment. (1)
United Kingdom
Indication: Unable to verify — no MHRA substance-file listing found in this pass (contrast: nifedipine and nicardipine both indexed cleanly). Do not present a UK dosing regimen.
Dose summary: Not available.
Renal context: Not available. (4)
Australia
Indication: Unable to verify — no Healthdirect listing found, ARTG not directly queryable by this pass's tooling.
Dose summary: Not available.
Renal context: Not available. (5)
Canada
Indication: Never authorised — confirmed absent from the Health Canada Drug Product Database via a direct, cross-checked API query.
Dose summary: Not applicable — do not present a Canadian dosing regimen.
Renal context: Not available. (3)
New Zealand
Indication: Unable to verify — no Medsafe data sheet found in this pass.
Dose summary: Not available.
Renal context: Not available. (6)
Hepatic guidance
Cirrhosis produces 4-5x higher plasma levels than in healthy subjects at the same dose; start at no more than 8.5 mg/day.
Overdose note
No nisoldipine-specific overdose experience documented in the label reviewed; treat per general dihydropyridine overdose principles (supportive care, limb elevation, careful calcium infusion, vasopressors, fluids). Dialysis unlikely to help due to high protein binding. (1)
Frequently asked questions
Why do I need to take nisoldipine on an empty stomach?
Food — especially a high-fat meal — dramatically changes how nisoldipine is absorbed: it can raise the peak level in your blood by up to 245% and lower total absorption by 25%. Taking it consistently on an empty stomach (1 hour before or 2 hours after a meal) keeps its effect predictable. (1)
Is nisoldipine used for angina?
No. Nisoldipine is FDA-approved for hypertension only, not angina. (1)
Can I take nisoldipine with phenytoin?
This combination should generally be avoided — taking phenytoin together with nisoldipine has been shown to lower nisoldipine to undetectable blood levels, meaning it may stop working. Tell your prescriber if you take phenytoin. (1)
Is nisoldipine safe while breastfeeding?
This is a genuine evidence gap, not a reassurance: no information at all is available on nisoldipine's use during breastfeeding. The NIH's LactMed database suggests nifedipine or nitrendipine may be preferred alternatives during lactation. Discuss this directly with your prescriber and your baby's healthcare provider. (2)
Is nisoldipine available outside the United States?
It is confirmed NOT authorised in Canada (absent from Health Canada's own Drug Product Database). Its status in the UK, Australia, and New Zealand could not be independently confirmed in this research pass — do not assume it is available in those countries. (3) (4) (5) (6)
What is the mechanism of action of nisoldipine?
Nisoldipine is a dihydropyridine calcium channel blocker with unusually low absolute bioavailability (~5%) due to extensive first-pass metabolism, >99% protein binding, and a terminal half-life of 13.7 ± 4.3 hours. Peak concentration is reached slowly (~9.2 hours). A high-fat meal increases Cmax by up to 245% and decreases AUC by 25% — the basis for the empty-stomach administration instruction. (1)
What is the generic name of Nisoldipine?
The generic name is nisoldipine. It is sold under brand names including SULAR (US, brand discontinued, generics remain). (1)
What class of drug is nisoldipine?
Nisoldipine is classed as: Calcium Channel Blocker (Dihydropyridine). (1)
References
- SULAR (nisoldipine) Extended-Release Tablets — prescribing informationDailyMed / FDA · United States · accessed 2026-07-27 · source 1
- Nisoldipine (LactMed entry LM200)LactMed, NICHD / NCBI Bookshelf · United States · accessed 2026-07-27 · source 2
- DPD active-ingredient API query for 'nisoldipine'Health Canada Drug Product Database, public API · Canada · accessed 2026-07-27 · source 3
- Absence of a NISOLDIPINE substance page in MHRA Products' indexed titlesMHRA Products (search-engine index of products.mhra.gov.uk) · United Kingdom · accessed 2026-07-27 · source 4
- No Healthdirect brand page or ARTG entry found for nisoldipineHealthdirect Australia / TGA ARTG (absence check) · Australia · accessed 2026-07-27 · source 5
- No Medsafe data sheet found for nisoldipineMedsafe (New Zealand) · New Zealand · accessed 2026-07-27 · source 6
- Nisoldipine XR Shortage: What Providers and Prescribers Need to Know (2026)MedFinder · United States · accessed 2026-07-27 · source 7
- Calcium Channel BlockersStatPearls, NCBI Bookshelf · class_level_not_country_specific · accessed 2026-07-27 · source 8
Brand names by country
Single-ingredient nisoldipine names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Sular17 mg, 8.5 mg, 34 mg · covis pharma us, inc