LISINOPRIL AND HYDROCHLOROTHIAZIDE
Clinical safety rating: avoid
NSAIDs may diminish the antihypertensive effect Lithium levels may be increased Risk of angioedema can occur at any time discontinue immediately.
Lisinopril is an ACE inhibitor that prevents conversion of angiotensin I to angiotensin II, reducing vasoconstriction and aldosterone secretion. Hydrochlorothiazide is a thiazide diuretic that inhibits sodium reabsorption in the distal convoluted tubule, increasing diuresis and lowering blood pressure.
| Metabolism | Lisinopril is not metabolized. Hydrochlorothiazide is minimally metabolized. |
| Excretion | Lisinopril: primarily renal (100% unchanged in urine). Hydrochlorothiazide: renal (≥95% unchanged via tubular secretion). |
| Half-life | Lisinopril: terminal half-life 12 hours, effective half-life ~30 hours due to prolonged ACE inhibition. Hydrochlorothiazide: terminal half-life 5.6-14.8 hours (mean 9.6 hours) in patients with normal renal function. |
| Protein binding | Lisinopril: negligible (<10%, no specific binding proteins identified). Hydrochlorothiazide: 40-68%, primarily to albumin. |
| Volume of Distribution | Lisinopril: Vd ~1.3 L/kg (0.9-1.7 L/kg), indicating extensive tissue binding. Hydrochlorothiazide: Vd ~0.8 L/kg (0.5-1.2 L/kg), distributed primarily in extracellular fluid. |
| Bioavailability | Lisinopril: oral bioavailability 25% (range 6-60%), unaffected by food. Hydrochlorothiazide: oral bioavailability 65-75% (mean 70% absolute). |
| Onset of Action | Lisinopril: 1 hour for peak effect, with antihypertensive effect seen within 1-2 hours. Hydrochlorothiazide: diuresis begins within 2 hours, maximal effect at 4-6 hours, antihypertensive effect takes days to weeks. |
| Duration of Action | Lisinopril: antihypertensive effect persists for 24 hours with once-daily dosing. Hydrochlorothiazide: diuretic effect lasts 6-12 hours; antihypertensive effect persists for 24 hours with chronic dosing. |
| Molecular Weight | Lisinopril: 441.52 Da; Hydrochlorothiazide: 297.74 Da |
Initial dose: 10 mg/12.5 mg orally once daily. Titrate based on blood pressure response; maximum 40 mg/25 mg per day.
| Dosage form | TABLET |
| Renal impairment | eGFR ≥30 mL/min: No adjustment. eGFR <30 mL/min: Not recommended. Avoid in severe renal impairment. |
| Liver impairment | Mild to moderate impairment (Child-Pugh A or B): No adjustment. Severe impairment (Child-Pugh C): Not recommended. |
| Pediatric use | Safety and efficacy not established; use not recommended under 18 years. |
| Geriatric use | Start at lower end of dosing (e.g., 10 mg/12.5 mg) due to increased risk of hypotension and electrolyte disturbances. Monitor renal function and electrolytes closely. |
| 1st trimester | Contraindicated due to risk of fetal renal dysfunction, oligohydramnios, and skull ossification defects associated with ACE inhibitors; thiazide diuretics may cause fetal electrolyte disturbances. Avoid use. |
| 2nd trimester | Contraindicated. ACE inhibitors and thiazides can cause fetal harm including oligohydramnios, fetal hypotension, and growth restriction. Discontinue if pregnancy is detected. |
| 3rd trimester | Contraindicated. Risk of neonatal hypotension, renal failure, and hyperkalemia from ACE inhibitors; thiazides may cause neonatal thrombocytopenia and electrolyte imbalance. |
Clinical note
NSAIDs may diminish the antihypertensive effect Lithium levels may be increased Risk of angioedema can occur at any time discontinue immediately.
| FDA category | Contraindicated |
| Placental transfer | Lisinopril crosses the placenta and has been detected in fetal tissue. Hydrochlorothiazide also crosses the placenta. Both are known to affect the fetus. |
■ FDA Black Box Warning
WARNING: ACE inhibitors cause fetal harm when used in pregnancy. Discontinue as soon as pregnancy is detected.
| Common Effects | heart failure |
| Serious Effects |
Hypersensitivity to lisinopril, hydrochlorothiazide, or sulfonamide-derived drugsHistory of angioedema related to previous ACE inhibitor therapyAnuriaHereditary or idiopathic angioedemaPregnancy
| Precautions | Angioedema, Hypotension, Renal impairment, Hyperkalemia, Hepatic impairment (thiazides), Electrolyte imbalance, Acute angle closure glaucoma (thiazides) |
| Food/Dietary | Avoid high-potassium foods (bananas, oranges, tomatoes, spinach, salt substitutes) due to lisinopril; limit sodium intake to enhance antihypertensive effect; reduce alcohol as it can potentiate hypotension; avoid grapefruit juice if taking with other medications that may interact. |
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| Breastfeeding | Hydrochlorothiazide is excreted in breast milk in low amounts; it may suppress lactation. Lisinopril is excreted at very low levels and is considered compatible with breastfeeding. However, due to potential for adverse effects in the infant (hypotension, electrolyte disturbances), caution is advised. Monitor infant for signs of dehydration or hypotension. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | First trimester: Exposure associated with increased risk of congenital malformations (cardiac, CNS) per ACE inhibitor class; limited data specific to combination. Second/third trimester: Oligohydramnios, fetal renal dysfunction, skull ossification defects, hypotension, hyperkalemia, and anuria due to fetal renin-angiotensin system depression. Hydrochlorothiazide crosses placenta; may cause fetal/neonatal electrolyte abnormalities and thrombocytopenia. |
| Fetal Monitoring | Baseline and serial renal function, serum electrolytes (potassium, sodium, chloride), blood pressure, urine output. Fetal ultrasound assessment for oligohydramnios, renal anomalies, and growth restriction after second trimester exposure. Neonatal monitoring for hypotension, electrolyte disturbances, and renal function. |
| Fertility Effects | No specific data; ACE inhibitors and thiazides are not known to impair fertility in humans. Animal studies show no significant reproductive toxicity. |
| Clinical Pearls | Monitor serum creatinine and potassium within 1-2 weeks of initiation or dose adjustment. Cough incidence is lower with lisinopril compared to other ACE inhibitors but still possible. Avoid use in pregnancy (ACE inhibitors are teratogenic). Use with caution in renal artery stenosis. Hydrochlorothiazide may exacerbate gout; check uric acid if symptoms occur. Onset of antihypertensive effect for lisinopril is 1 hour, peak at 6 hours; hydrochlorothiazide effect peaks at 4-6 hours. Consider dose timing to minimize nocturia from diuretic effect. |
| Patient Advice | Take this medication exactly as prescribed, usually once daily. It controls but does not cure high blood pressure. · Avoid salt substitutes containing potassium while on lisinopril; they can cause dangerously high potassium levels. · Report any persistent dry cough, swelling of face/lips/tongue, difficulty breathing, or signs of infection (fever, sore throat). · If you experience lightheadedness or dizziness, especially when standing up quickly, sit or lie down and avoid sudden position changes. · Do not become pregnant while taking this medication; discuss effective contraception with your doctor. · This combination may increase sun sensitivity; use sunscreen and protective clothing. · Do not discontinue this medication abruptly without consulting your healthcare provider. |