Nefrix (Hydrochlorothiazide)

Hydrochlorothiazide acts on the renal distal convoluted tubule to manage fluid balance and vascular resistance, making it useful in several cardiovascular and renal conditions.

• Hypertension: lowers systemic blood pressure by reducing plasma volume.
• Edema associated with heart failure: promotes fluid excretion to relieve congestion.
• Edema due to renal disease: assists in removing excess interstitial fluid.
• Edema secondary to liver cirrhosis: decreases ascites and peripheral swelling.

• Hydrochlorothiazide inhibits the Na+/Cl- symporter in the distal convoluted tubule of the kidney, leading to increased urinary excretion of sodium, chloride, and water. This diuretic effect reduces extracellular fluid volume, decreases cardiac preload, and ultimately lowers systemic vascular resistance, contributing to blood pressure reduction.

Hydrochlorothiazide may cause a range of adverse reactions, from mild to severe, depending on patient factors and concomitant therapies.

Common Side Effects

• Increased urination: more frequent or larger volume of urine.
• Electrolyte imbalance: low potassium or sodium levels.
• Dizziness or light‑headedness, especially upon standing.
• Headache.
• Fatigue.
• Elevated blood glucose levels.

Serious or Rare Side Effects

• Severe dehydration or hypotension.
• Significant electrolyte disturbances such as hyponatremia or hypokalemia.
• Gout flare due to increased uric acid.
• Pancreatitis.
• Allergic reactions including rash, angioedema, or anaphylaxis.
• Blood dyscrasias such as agranulocytosis or thrombocytopenia.

When prescribing or dispensing Hydrochlorothiazide, clinicians should consider several safety measures.

• Monitor electrolytes: check serum potassium, sodium, and magnesium regularly.
• Assess renal function: evaluate creatinine and eGFR before initiation and during therapy.
• Use cautiously in diabetes: may affect glucose control.
• Avoid abrupt discontinuation: taper to prevent rebound hypertension.
• Adjust dose in elderly patients: start low and monitor for orthostatic changes.
• Store at room temperature: keep in the original pack, protect from moisture.

Hydrochlorothiazide can alter the pharmacokinetics or pharmacodynamics of several medicines.

Major Interactions (Avoid)

• Lithium: increased risk of lithium toxicity.
• NSAIDs: may blunt diuretic efficacy and affect renal function.
• ACE inhibitors or ARBs: heightened risk of severe hypotension and renal impairment.

Moderate Interactions (Monitor Closely)

• Digoxin: low potassium can increase digoxin toxicity.
• Warfarin: may alter INR and bleeding risk.
• Antidiabetic agents: enhanced hypoglycaemic effect.
• Corticosteroids: may counteract diuretic sodium‑loss effect.