BENICAR HCT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BENICAR HCT (BENICAR HCT).
Combination of an angiotensin II receptor blocker (ARB) and a thiazide diuretic. Olmesartan blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively antagonizing the AT1 receptor. Hydrochlorothiazide inhibits the sodium-chloride symporter in the distal convoluted tubule, increasing excretion of sodium, chloride, and water, thereby reducing plasma volume.
| Metabolism | Olmesartan is metabolized in the liver via glucuronidation (UGT2B7, UGT1A3, UGT1A9) and oxidation (CYP2C9). Hydrochlorothiazide is not significantly metabolized and is excreted unchanged in urine. |
| Excretion | Olmesartan: Approximately 50-65% of absorbed dose excreted in urine (10-20% as unchanged drug, remainder as metabolites), 35-50% in feces via biliary excretion. Hydrochlorothiazide: ≥95% excreted renally as unchanged drug. |
| Half-life | Olmesartan: Terminal elimination half-life is 10-15 hours, supporting once-daily dosing. Hydrochlorothiazide: Terminal half-life is 5.6-14.8 hours (mean ~10 hours), prolonged in renal impairment. |
| Protein binding | Olmesartan: ≥99% bound to plasma proteins, primarily albumin. Hydrochlorothiazide: 40-68% bound to plasma proteins, predominantly albumin. |
| Volume of Distribution | Olmesartan: Vd is approximately 17 L (0.24 L/kg for a 70 kg adult), indicating limited extravascular distribution. Hydrochlorothiazide: Vd is 0.4-1.0 L/kg (mean 0.8 L/kg), indicating extensive distribution into tissues. |
| Bioavailability | Olmesartan: Absolute oral bioavailability is 26-29%, with food not affecting absorption. Hydrochlorothiazide: Oral bioavailability is 65-75%, reduced in congestive heart failure. |
| Onset of Action | Olmesartan: Onset of antihypertensive effect within 1-2 hours after oral administration, peak effect at 6-8 hours. Hydrochlorothiazide: Onset of diuresis within 2 hours, peak at 4-6 hours. |
| Duration of Action | Olmesartan: Duration of antihypertensive effect is 24 hours, consistent with once-daily dosing. Hydrochlorothiazide: Diuretic effect lasts approximately 6-12 hours; antihypertensive effect may persist for 24 hours after chronic dosing. |
One tablet orally once daily. Available strengths: 40 mg olmesartan / 12.5 mg hydrochlorothiazide, 40 mg olmesartan / 25 mg hydrochlorothiazide. Dose may be titrated after 2-4 weeks based on response.
| Dosage form | TABLET |
| Renal impairment | Contraindicated in anuria. For CrCl 30-60 mL/min: maximum hydrochlorothiazide dose 12.5 mg/day. For CrCl <30 mL/min: not recommended. |
| Liver impairment | Child-Pugh Class A: no adjustment; Class B: caution with hydrochlorothiazide; Class C: contraindicated (hydrochlorothiazide contraindicated in severe hepatic impairment). |
| Pediatric use | Not indicated in pediatric patients <18 years of age. No established dosing. |
| Geriatric use | Start at lowest available strength (40/12.5 mg) once daily with close monitoring of renal function, blood pressure, and electrolytes. Avoid volume depletion. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for BENICAR HCT (BENICAR HCT).
| Breastfeeding | Unknown if olmesartan or HCTZ are excreted in human milk. HCTZ is excreted in breast milk in small amounts; no M/P ratio available. Potential for adverse effects in nursing infant; use caution, especially in neonates. |
| Teratogenic Risk | Pregnancy Category D. First trimester: risk of congenital malformations (e.g., oligohydramnios, renal dysgenesis) with ACE inhibitors; similar risk for ARB component (olmesartan). Second and third trimesters: fetal hypotension, oligohydramnios, anuria, renal failure, skull hypoplasia, and death. Avoid in pregnancy. |
■ FDA Black Box Warning
WARNING: FETAL TOXICITY. Drugs that act directly on the renin-angiotensin system (RAS) can cause injury and death to the developing fetus. Discontinue as soon as possible once pregnancy is detected.
| Serious Effects |
["Anuria","Hypersensitivity to olmesartan, hydrochlorothiazide, or sulfonamide-derived drugs","Concomitant use with aliskiren in patients with diabetes or renal impairment (GFR < 60 mL/min/1.73 m²)","Pregnancy"]
| Precautions | ["Fetal toxicity: Discontinue if pregnancy is detected","Hypotension in volume- or salt-depleted patients","Electrolyte imbalances (especially hypokalemia, hyponatremia, hypomagnesemia) due to hydrochlorothiazide component","Renal function impairment: Monitor renal status","Acute myopia and secondary angle-closure glaucoma (with HCTZ)","Sulfonamide allergy: HCTZ is a sulfonamide derivative","Exacerbation of systemic lupus erythematosus (with HCTZ)"] |
| Food/Dietary | Avoid high-potassium foods (bananas, oranges, potatoes, tomatoes, spinach, salt substitutes) due to risk of hyperkalemia. Grapefruit juice may increase drug absorption; avoid excessive consumption. |
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| Fetal Monitoring |
| Monitor maternal blood pressure, renal function, serum electrolytes, and urine output. Fetal ultrasound for oligohydramnios and renal function. Check fetal heart rate and growth. |
| Fertility Effects | No direct studies. HCTZ may cause electrolyte imbalances affecting reproductive function. ARBs may reduce renal function in women with renal disease, potentially impacting fertility. No known major effect. |
| Clinical Pearls | Monitor serum creatinine and potassium within 2 weeks of initiation or dose changes. Avoid in patients with bilateral renal artery stenosis. Combination increases risk of hyperkalemia, hypotension, and renal impairment. Contraindicated with history of angioedema from ACEi or ARB. |
| Patient Advice | Take exactly as prescribed, usually once daily with or without food. · Avoid salt substitutes containing potassium. · Report symptoms like lightheadedness, fainting, swelling of face/lips/tongue, or difficulty breathing. · Stay hydrated, especially in hot weather or during exercise. · Avoid alcohol and NSAIDs (e.g., ibuprofen, naproxen) without consulting your doctor. |