CANDESARTAN CILEXETIL AND HYDROCHLOROTHIAZIDE
Clinical safety rating: safe
Other antihypertensive drugs can have additive effects Lithium levels may be increased Can cause hypokalemia and hyponatremia.
Candesartan cilexetil is a prodrug that is hydrolyzed to candesartan, an angiotensin II receptor blocker (ARB) that selectively antagonizes AT1 receptors, leading to vasodilation, reduced aldosterone secretion, and decreased blood pressure. Hydrochlorothiazide is a thiazide diuretic that inhibits sodium and chloride reabsorption in the distal convoluted tubule, promoting diuresis and further lowering blood pressure.
| Metabolism | Candesartan cilexetil is rapidly hydrolyzed to candesartan by esterases in the intestinal wall and liver. Candesartan is further metabolized by CYP2C9 to an inactive metabolite. Hydrochlorothiazide is not metabolized significantly and is excreted unchanged in urine. |
| Excretion | Candesartan: ~33% renal, ~67% biliary/fecal as unchanged drug and inactive metabolites. Hydrochlorothiazide: ≥95% renal as unchanged drug. |
| Half-life | Candesartan: Terminal t1/2 ~9 hours (linear); clinically, once-daily dosing provides 24-hour antihypertensive effect. Hydrochlorothiazide: Terminal t1/2 ~6-15 hours (averaging 10 hours), prolonged in renal impairment. |
| Protein binding | Candesartan: >99% bound to albumin. Hydrochlorothiazide: ~40-70% bound to albumin. |
| Volume of Distribution | Candesartan: Vd ~0.13 L/kg (approximate; distribution is limited, primarily in extracellular fluid). Hydrochlorothiazide: Vd ~0.8-1.0 L/kg (distributes extensively into tissues). |
| Bioavailability | Candesartan: Absolute bioavailability is ~14% (candesartan cilexetil is a prodrug, rapidly and completely converted to candesartan; absorption is unaffected by food). Hydrochlorothiazide: Oral bioavailability is ~65-70% of an orally administered dose, with modest variation. |
| Onset of Action | Candesartan: Onset within 2-4 hours after oral administration; peak effect at 6-8 hours. Hydrochlorothiazide: Onset occurs within 2 hours of oral dosing. |
| Duration of Action | Candesartan: Duration of action exceeds 24 hours, supporting once-daily dosing. Hydrochlorothiazide: Duration is 6-12 hours, but antihypertensive effect persists for 24 hours with long-term therapy due to vascular effects. |
1 tablet (candesartan cilexetil 16 mg/hydrochlorothiazide 12.5 mg) orally once daily. Maximum dose: 1 tablet (32 mg/25 mg) once daily.
| Dosage form | TABLET |
| Renal impairment | Contraindicated if GFR <30 mL/min/1.73 m². For GFR 30-60 mL/min/1.73 m²: maximum dose of candesartan 16 mg and hydrochlorothiazide 12.5 mg once daily. Monitor renal function and electrolytes. |
| Liver impairment | Child-Pugh Class A: No adjustment necessary. Child-Pugh Class B: Initiate at 1 tablet (8 mg/12.5 mg) once daily; maximum dose 16 mg/12.5 mg once daily. Child-Pugh Class C: Contraindicated. |
| Pediatric use | Not approved in pediatric patients. Safety and efficacy not established. |
| Geriatric use | Initiate at 1 tablet (8 mg/12.5 mg) once daily; titrate slowly. Monitor renal function and serum potassium. Lower starting dose recommended due to increased risk of hypotension and electrolyte imbalance. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other antihypertensive drugs can have additive effects Lithium levels may be increased Can cause hypokalemia and hyponatremia.
| FDA category | Animal |
| Breastfeeding | Candesartan is excreted into human milk in small amounts; hydrochlorothiazide is also excreted. M/P ratio for candesartan is approximately 0.1. Theoretical risk of neonatal hypotension and renal effects. Use with caution, especially in preterm or low birth weight infants. |
| Teratogenic Risk |
■ FDA Black Box Warning
Fetal toxicity: Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus. Discontinue as soon as possible once pregnancy is detected.
| Common Effects | edema |
| Serious Effects |
["Hypersensitivity to candesartan, hydrochlorothiazide, or any component","Anuria","Pregnancy","Severe renal impairment (CrCl <30 mL/min)","History of angioedema with ARBs or ACE inhibitors"]
| Precautions | ["Fetal/neonatal morbidity and mortality","Hypotension in volume-depleted patients","Impaired renal function","Electrolyte imbalances (hyponatremia, hypokalemia, hypercalcemia)","Acute angle-closure glaucoma (with hydrochlorothiazide)","Sulfonamide allergy (hydrochlorothiazide is a sulfonamide derivative)","Exacerbation of systemic lupus erythematosus"] |
| Food/Dietary |
Loading safety data…
| First trimester: Exposure associated with potential risk of renal malformations and oligohydramnios due to angiotensin II receptor antagonist effects. Second and third trimesters: Known to cause fetal renal dysfunction, oligohydramnios, skull ossification defects, hypotension, and anuria. Risk is dose-related and increases with later exposure. Avoid use in pregnancy. |
| Fetal Monitoring | Maternal: Blood pressure, renal function (serum creatinine, BUN), electrolytes, uric acid. Fetal: Ultrasound monitoring for amniotic fluid volume and fetal growth if exposed in second/third trimester. Neonatal: Monitor for hypotension, oliguria, and hyperkalemia. |
| Fertility Effects | No specific human studies; animal studies show no adverse effects on fertility. Theoretical concerns due to angiotensin II receptor blockade on reproductive tissues, but clinical significance unknown. |
| Avoid consuming high-potassium foods (e.g., bananas, oranges, potatoes, spinach, avocados) in large amounts unless directed by a doctor. Limit alcohol intake. Maintain adequate fluid intake to prevent dehydration but avoid excessive fluid intake. Grapefruit juice has no significant interaction with candesartan or hydrochlorothiazide. |
| Clinical Pearls | Monitor serum potassium and creatinine within 2 weeks of initiation or dose change; candesartan increases potassium while HCTZ decreases it, but net effect may be hyperkalemia in CKD. HCTZ efficacy decreases when eGFR <30 mL/min/1.73m2; avoid use in severe renal impairment. Combination may cause symptomatic hypotension, especially in volume-depleted patients. Use with caution in patients with history of angioedema or bilateral renal artery stenosis. |
| Patient Advice | Take this medication exactly as prescribed, usually once daily. Do not skip doses or take double doses. · If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your regular schedule. · This medication may cause dizziness or lightheadedness, especially during the first few days. Avoid driving or operating machinery until you know how it affects you. · Avoid alcohol, as it can increase dizziness and lower blood pressure further. · Do not use potassium supplements or salt substitutes containing potassium without consulting your doctor. · Wear sunscreen and protective clothing, as hydrochlorothiazide may increase sensitivity to sunlight (photosensitivity). · Report any signs of dehydration (e.g., excessive thirst, dry mouth, muscle cramps, weakness) or allergic reactions (e.g., swelling of face, tongue, throat, difficulty breathing) to your doctor immediately. · Regular monitoring of blood pressure, kidney function, and electrolyte levels is required. |