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ACE inhibitor + thiazide diuretic Pregnancy: WARNING: FETAL TOXICITY. When pregnancy is detected, discontinue quinapril and hydrochlorothiazide tablets as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus.

Quinapril with hydrochlorothiazide

Brand names: Accuretic

This is a fixed-dose oral combination of quinapril, an ACE inhibitor, with hydrochlorothiazide, a thiazide diuretic, used for essential hypertension not adequately controlled on quinapril alone.

Adult dose

Dose: Hypertension not adequately controlled with quinapril monotherapy (the fixed combination is not for initial therapy): quinapril/hydrochlorothiazide tablets 10/12.5 mg or 20/12.5 mg (mg quinapril / mg hydrochlorothiazide)
Route: Oral (tablets)
Frequency: Dosing frequency of the combination tablet is not stated in the retrieved label text (quinapril monotherapy is described as once-daily doses); do not generally increase the hydrochlorothiazide dose until 2 to 3 weeks have elapsed
'This fixed combination is not indicated for the initial therapy of hypertension.' Label: 'Patients whose blood pressures are not adequately controlled with quinapril monotherapy may instead be given quinapril and hydrochlorothiazide tablets 10/12.5 or 20/12.5. Further increases of either or both components could depend on clinical response. The hydrochlorothiazide dose should generally not be increased until 2 to 3 weeks have elapsed.' Switch from hydrochlorothiazide: 'Patients whose blood pressures are adequately controlled with 25 mg of daily hydrochlorothiazide, but who experience significant potassium loss with this regimen, may achieve blood pressure control with less electrolyte disturbance if they are switched to quinapril and hydrochlorothiazide tablets 10/12.5 or 20/12.5.' Replacement therapy: 'patients who are adequately treated with 20 mg of quinapril and 25 mg of hydrochlorothiazide and experience no significant electrolyte disturbances may instead wish to receive quinapril and hydrochlorothiazide tablets 20/25.' Available strengths (How Supplied): 10/12.5 (10 mg quinapril + 12.5 mg hydrochlorothiazide), 20/12.5 and 20/25. As monotherapy, quinapril is effective in once-daily doses of 10 to 80 mg and hydrochlorothiazide in doses of 12.5 to 50 mg; the 2.5 to 40 mg quinapril and 6.25 to 25 mg hydrochlorothiazide ranges are CLINICAL-TRIAL doses, not recommendations. The retrieved posology section is not truncated and prints no maximum dose for the combination, so maxDose is left empty. To minimise dose-independent side effects it is usually appropriate to begin combination therapy only after a patient has failed to achieve the desired effect with monotherapy. Black patients receiving ACE inhibitor monotherapy have a higher reported incidence of angioedema and a smaller blood pressure effect than non-blacks. No UK SPC for quinapril with hydrochlorothiazide is listed on eMC — this dose is from US prescribing information (Quinapril and Hydrochlorothiazide tablets, Chartwell RX, LLC) and must be verified against UK practice.

Dose adjustments

Renal

Regimens of therapy with quinapril and hydrochlorothiazide tablets need not take account of renal function as long as the patient's creatinine clearance is >30 mL/min/1.73 m2 (serum creatinine roughly <=3 mg/dL or 265 µmol/L). In patients with more severe renal impairment, loop diuretics are preferred to thiazides; therefore the combination is not recommended for use in these patients.

Hepatic

Not stated in the product information we used — check the full SPC.

Dose independently re-sourced from US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to quinapril or hydrochlorothiazide
  • History of angioedema related to previous treatment with an ACE inhibitor
  • Combination with a neprilysin inhibitor (e.g. sacubitril); do not administer within 36 hours of switching to or from sacubitril/valsartan
  • Anuria or hypersensitivity to other sulfonamide-derived drugs (because of the hydrochlorothiazide component)
  • Do not co-administer with aliskiren in patients with diabetes

Side effects

  • Headache (6.7% vs 30.0% on placebo in controlled trials), dizziness (4.8%), coughing (3.2%), fatigue (2.9%), myalgia (2.4%)
  • Rhinitis (2.0%), viral infection (1.9%), nausea and/or vomiting (1.8%), abdominal pain (1.7%), back pain (1.5%), diarrhoea (1.4%)
  • Discontinuation required in 2.1% of patients in controlled studies; the most common reasons were cough (1.0%) and headache (0.7%)
  • Hydrochlorothiazide-associated reactions include orthostatic hypotension, pancreatitis, jaundice (intrahepatic cholestatic), sialadenitis, vertigo, paraesthesia, muscle spasm, aplastic anaemia, agranulocytosis, leukopenia, thrombocytopenia, haemolytic anaemia, renal failure, interstitial nephritis, hyperglycaemia, glycosuria and hyperuricaemia (the retrieved adverse-reactions text is truncated at source-fetch limit part-way through the hypersensitivity group)
  • Another ACE inhibitor, captopril, has caused agranulocytosis, particularly in patients with renal impairment or collagen-vascular disease; available data are insufficient to show quinapril does not have a similar risk

Interactions

  • Neprilysin inhibitors (e.g. sacubitril) - contraindicated in combination; do not administer within 36 hours of switching to or from sacubitril/valsartan
  • Aliskiren - do not co-administer in patients with diabetes
  • Alcohol, barbiturates or narcotics may potentiate orthostatic hypotension (hydrochlorothiazide component)

Monitoring

  • Blood pressure response - further increases of either or both components depend on clinical response
  • Serum potassium and electrolytes - hypokalaemia is the main dose-dependent effect of the hydrochlorothiazide component
  • Renal function - creatinine clearance (combination not recommended when creatinine clearance is 30 mL/min/1.73 m2 or less)
  • Pregnancy status - discontinue as soon as possible when pregnancy is detected

Clinical monograph

How it works

Quinapril inhibits angiotensin-converting enzyme to lower angiotensin-II-mediated vasoconstriction and aldosterone secretion, while hydrochlorothiazide increases renal sodium and water excretion; the ACE inhibitor offsets diuretic-induced renin-angiotensin activation.

Prescribing in practice

  • Avoid in pregnancy because the ACE-inhibitor component is foetotoxic; counsel women of childbearing potential and review contraception.
  • ACE inhibitors can cause angioedema requiring permanent withdrawal and a persistent dry cough, while the thiazide adds risks of hyponatraemia, hypokalaemia, hyperuricaemia and glucose intolerance.
  • First-dose hypotension, hyperkalaemia and renal impairment can occur, especially with volume depletion, renal artery stenosis or NSAIDs.

Monitoring

Monitor blood pressure, renal function and serum electrolytes including sodium and potassium at baseline and after dose changes.

Counselling the patient

  • Seek urgent help for swelling of the face, lips, tongue or throat.
  • Report a persistent dry cough so an alternative can be considered.
  • Tell your doctor immediately if you become pregnant.

Evidence & guidelines

Combining an ACE inhibitor with a thiazide diuretic is an established step in NICE hypertension management, and the fixed-dose combination supports adherence.

Reference: NICE NG136; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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