Irbesartan/Hydrochlorothiazide Macleods Pharma Uk (Hydrochlorothiazide, Irbesartan)

Irbesartan/Hydrochlorothiazide is an antihypertensive combination that targets the renin‑angiotensin system and promotes diuresis.

• Hypertension: reduces systolic and diastolic blood pressure in adults with primary hypertension.
• Hypertension with fluid retention: improves blood pressure control when excess fluid contributes to elevated pressure.
• Uncontrolled hypertension on monotherapy: provides additional blood pressure lowering when a single agent is insufficient.

• Irbesartan selectively blocks AT1 receptors, preventing angiotensin II from causing vasoconstriction and aldosterone release. Hydrochlorothiazide acts on the distal convoluted tubule to inhibit NaCl reabsorption, increasing urinary sodium and water excretion, which lowers plasma volume. The combined actions result in reduced peripheral resistance and blood volume, leading to a sustained decrease in arterial blood pressure.

The following adverse reactions have been reported with the Irbesartan/Hydrochlorothiazide combination.

Common Side Effects

• Dizziness: light‑headed sensation, especially after standing.
• Headache: mild to moderate intensity.
• Increased urination: due to the diuretic component.
• Electrolyte imbalance: low potassium or sodium levels.
• Fatigue: general feeling of tiredness.
• Mild gastrointestinal upset: nausea or abdominal discomfort.

Serious or Rare Side Effects

• Severe dehydration: marked fluid loss requiring medical attention.
• Acute kidney injury: sudden decline in renal function.
• Hyperkalemia: elevated potassium that can affect heart rhythm.
• Allergic reactions: rash, itching, or swelling.
• Blood dyscrasias: rare blood cell disorders such as agranulocytosis.

Before initiating therapy, clinicians should consider several safety measures.

• Monitor blood pressure: ensure target values are achieved and maintained.
• Assess renal function: obtain baseline creatinine and eGFR, repeat periodically.
• Check electrolytes: especially potassium and sodium levels during treatment.
• Avoid use in severe hepatic impairment: limited data on safety.
• Pregnancy and lactation: not recommended due to potential fetal risk.
• Store at room temperature: keep in the original pack, protect from moisture and direct sunlight.

Irbesartan/Hydrochlorothiazide may interact with other medicines, requiring attention to the level of risk.

Major Interactions (Avoid)

• Potassium‑sparing diuretics: increased risk of hyperkalemia.
• ACE inhibitors or ARBs combined with aliskiren in diabetic patients: heightened renal adverse events.
• Lithium: thiazide component can raise lithium concentrations, leading to toxicity.
• NSAIDs: may blunt antihypertensive effect and impair renal function.

Moderate Interactions (Monitor Closely)

• Other antihypertensives (beta‑blockers, calcium channel blockers): additive blood pressure lowering.
• CYP2C9 inhibitors (e.g., fluconazole): may increase irbesartan plasma levels.
• Antidiabetic agents: diuretic‑induced changes in glucose control may require dose adjustment.