Usage
- Hydrochlorothiazide + Olmesartan Medoxomil is prescribed for the treatment of essential hypertension (high blood pressure) in adults whose blood pressure is not adequately controlled by olmesartan medoxomil alone or hydrochlorothiazide alone. It is not indicated for initial therapy.
- Pharmacological classification: Antihypertensive; a combination of an angiotensin II receptor blocker (ARB) and a thiazide diuretic.
- Mechanism of Action: Olmesartan blocks the action of angiotensin II, a hormone that causes blood vessels to constrict, leading to vasodilation. Hydrochlorothiazide increases the excretion of sodium and water by the kidneys, reducing blood volume and further lowering blood pressure.
Alternate Names
- Olmesartan medoxomil/hydrochlorothiazide
- Olmesartan medoxomil/HCTZ
- Brand Names: Benicar HCT, Olmetec Plus HCT (and various generics)
How It Works
- Pharmacodynamics: Olmesartan, an ARB, selectively blocks the angiotensin II type 1 (AT1) receptor, inhibiting the vasoconstricting and aldosterone-secreting effects of angiotensin II. Hydrochlorothiazide, a thiazide diuretic, inhibits sodium reabsorption in the distal convoluted tubule of the nephron, increasing sodium and water excretion. This leads to decreased blood volume and peripheral vascular resistance, thereby lowering blood pressure.
- Pharmacokinetics: Absorption: Olmesartan medoxomil is an oral prodrug rapidly hydrolyzed to the active metabolite olmesartan during absorption from the gastrointestinal tract. Hydrochlorothiazide is also well-absorbed orally. Metabolism: Olmesartan undergoes minimal metabolism. Hydrochlorothiazide is not extensively metabolized. Elimination: Olmesartan is eliminated primarily in bile and feces, with a small amount in urine. Hydrochlorothiazide is excreted primarily unchanged in the urine.
- Mode of Action: Olmesartan exerts its effects by competitively binding to and blocking AT1 receptors, preventing angiotensin II binding. Hydrochlorothiazide inhibits the sodium-chloride symporter in the distal tubule, reducing sodium reabsorption.
- Receptor binding: Olmesartan binds selectively to AT1 receptors.
- Elimination pathways: Olmesartan is primarily eliminated through biliary/fecal excretion, with a small portion in urine. Hydrochlorothiazide is excreted mainly unchanged in the urine.
Dosage
Standard Dosage
Adults:
- Initial dose: 20/12.5 mg (olmesartan/hydrochlorothiazide) once daily. If blood pressure remains uncontrolled with olmesartan monotherapy, increase to 40/12.5 mg once daily or titrate up to a maximum of 40/25 mg, as needed. For patients uncontrolled with hydrochlorothiazide alone, begin with 20/12.5 mg. Dosage adjustments should be made at 2-4 week intervals.
Children:
- Not recommended for use in children under 18 years of age. Safety and efficacy have not been established.
Special Cases:
- Elderly Patients: Initiate therapy at the lower end of the dosing range (20/12.5 mg) due to the potential for decreased hepatic, renal, or cardiac function.
- Patients with Renal Impairment: No dosage adjustment necessary for mild to moderate renal impairment (CrCl > 30 mL/min). Not recommended in severe renal impairment (CrCl ≤ 30 mL/min).
- Patients with Hepatic Dysfunction: Start with a lower dose of 10 mg olmesartan once daily in moderate hepatic impairment, not exceeding 20 mg daily. Close monitoring of blood pressure and renal function is advised in patients with hepatic impairment who are receiving diuretics and/or other antihypertensive agents. Not recommended in severe hepatic impairment.
- Patients with Comorbid Conditions: Close monitoring is recommended for patients with heart failure, diabetes, or other conditions. In patients with diabetes, avoid concomitant use with aliskiren.
Clinical Use Cases
- This medication is not typically used in clinical settings like intubation, surgical procedures, mechanical ventilation, ICU, or emergency situations. Its primary use is for chronic hypertension management in an outpatient setting.
Dosage Adjustments
- Adjust dosages based on patient response and tolerability, monitoring blood pressure, renal function, and electrolytes. Patients with hepatic or renal impairment may require dose reductions.
Side Effects
Common Side Effects
- Dizziness, lightheadedness, headache
- Upper respiratory tract infections (e.g., stuffy nose, sore throat)
- Back pain, fatigue
- Increased uric acid levels
- Diarrhea, nausea, vomiting
Rare but Serious Side Effects
- Angioedema (swelling of face, lips, tongue, or throat)
- Hypotension
- Renal failure
- Electrolyte imbalances (hypokalemia, hyponatremia)
- Rhabdomyolysis
- Liver dysfunction
Long-Term Effects
- Potential for electrolyte imbalances, renal dysfunction, and cardiovascular events if hypertension is not adequately controlled.
Adverse Drug Reactions (ADR)
- Angioedema, acute renal failure, severe hypotension, rhabdomyolysis.
Contraindications
- Pregnancy (especially second and third trimesters)
- Anuria
- Hypersensitivity to olmesartan, hydrochlorothiazide, or sulfonamides
- Concomitant use of aliskiren in patients with diabetes
Drug Interactions
- Other antihypertensives (additive hypotensive effect)
- Potassium-sparing diuretics, potassium supplements (risk of hyperkalemia)
- Lithium (increased lithium levels)
- NSAIDs (decreased antihypertensive effect, increased risk of renal impairment)
- Dual blockade of the renin-angiotensin system (increased risk of hypotension, hyperkalemia, and renal dysfunction)
- Colesevelam hydrochloride (reduced olmesartan absorption)
Pregnancy and Breastfeeding
- Pregnancy Safety Category: D (contraindicated in second and third trimesters)
- Fetal risks: Renal failure, growth retardation, lung hypoplasia, skeletal malformations, death
- Breastfeeding: Not recommended; olmesartan and hydrochlorothiazide are excreted in breast milk.
Drug Profile Summary
- Mechanism of Action: ARB and thiazide diuretic combination; blocks angiotensin II receptors and increases sodium and water excretion.
- Side Effects: Dizziness, headache, upper respiratory infections, hyperuricemia, electrolyte imbalances, renal impairment.
- Contraindications: Pregnancy, anuria, hypersensitivity, concomitant use of aliskiren in patients with diabetes.
- Drug Interactions: Other antihypertensives, potassium supplements, lithium, NSAIDs.
- Pregnancy & Breastfeeding: Contraindicated in pregnancy; not recommended during breastfeeding.
- Dosage: Adults: 20/12.5 mg once daily, titrated up to 40/25 mg as needed. Not recommended for children.
- Monitoring Parameters: Blood pressure, renal function, electrolytes (potassium, sodium, magnesium), uric acid, creatinine.
Popular Combinations
- Commonly used alone or in combination with other antihypertensive agents when blood pressure is not controlled with dual therapy.
Precautions
- General Precautions: Monitor renal function, electrolytes, and blood pressure closely. Evaluate patients for volume or salt depletion before initiating therapy.
- Specific Populations: See section on “Dosage - Special Cases” for details related to pregnant women, breastfeeding mothers, children, and the elderly.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Hydrochlorothiazide + Olmesartan Medoxomil?
A: The initial recommended dose is 20/12.5 mg once daily. It can be titrated up to a maximum of 40/25 mg based on the patient’s blood pressure response and tolerability.
Q2: Can this medication be used during pregnancy?
A: No, it is contraindicated during the second and third trimesters of pregnancy due to the risk of fetal harm. It should be discontinued as soon as pregnancy is detected.
Q3: What are the most common side effects?
A: Common side effects include dizziness, lightheadedness, headache, upper respiratory infections, and elevated uric acid levels.
Q4: Are there any serious side effects I should be aware of?
A: Yes, although rare, serious side effects include angioedema, hypotension, renal failure, and electrolyte imbalances.
Q5: What should I monitor in patients taking this medication?
A: Monitor blood pressure, renal function (serum creatinine), and electrolytes, especially potassium, sodium, and magnesium levels.
Q6: Can this medication interact with other drugs?
A: Yes, it can interact with other antihypertensives, potassium supplements, lithium, and NSAIDs, among others.
Q7: What should I do if a patient develops angioedema?
A: Discontinue the medication immediately and provide appropriate medical care. Angioedema is a serious allergic reaction that requires urgent attention.
Q8: Is there a specific diet patients should follow while on this medication?
A: Patients should maintain a healthy diet and may need to restrict sodium intake depending on their blood pressure response. Potassium intake should be monitored and adjusted as needed based on serum potassium levels. Patients should avoid potassium supplements unless prescribed by a physician.
Q9: Can patients drink alcohol while taking this medication?
A: Alcohol consumption can exacerbate the hypotensive effects of this medication, so patients should be advised to limit or avoid alcohol intake.
Q10: Can this medication be crushed or chewed?
A: No, the tablets should be swallowed whole with water. Do not crush or chew the tablets.
