Modamide (Amiloride Hydrochloride Dihydrate)

Modamide is a potassium‑sparing diuretic used in conditions where sodium retention contributes to fluid overload.

• Hypertension: helps lower blood pressure by reducing sodium reabsorption while preserving potassium.
• Congestive heart‑failure edema: decreases fluid accumulation in the lungs and peripheral tissues.
• Nephrotic syndrome: limits protein‑loss‑related edema by promoting modest diuresis without worsening potassium loss.

• Amiloride blocks epithelial sodium channels (ENaC) located in the distal convoluted tubule and collecting duct of the nephron. By inhibiting sodium entry through these channels, the drug reduces sodium reabsorption, leading to a modest increase in urinary sodium excretion while sparing potassium, thereby producing a mild diuretic effect without significant potassium loss.

Adverse reactions may occur with any medication and should be monitored by the prescriber.

Common Side Effects

• Dizziness
• Headache
• Nausea or upset stomach
• Fatigue
• Muscle cramps
• Mild hyperkalemia (elevated potassium)

Serious or Rare Side Effects

• Severe hyperkalemia leading to cardiac arrhythmia
• Acute renal impairment
• Significant hypotension
• Allergic skin reactions (rash, urticaria)
• Metabolic acidosis
• Pulmonary edema in rare cases

Before initiating therapy, clinicians should assess patient‑specific factors and monitor relevant parameters.

• Monitor serum potassium: avoid excessive accumulation, especially with other potassium‑sparing agents.
• Assess renal function: dose adjustment may be required in reduced clearance.
• Use caution in diabetic patients: potassium shifts can affect glucose control.
• Avoid in severe renal impairment unless benefits outweigh risks.
• Adjust dose in elderly patients due to altered pharmacodynamics.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Amiloride can affect the pharmacodynamics of several co‑administered drugs.

Major Interactions (Avoid)

• ACE inhibitors or ARBs: may cause dangerous hyperkalemia.
• Other potassium‑sparing diuretics (e.g., spironolactone): increase risk of severe hyperkalemia.
• Potassium supplements or salt substitutes containing potassium.
• Trimethoprim: additive effect on potassium levels.
• Lithium: may increase lithium toxicity.

Moderate Interactions (Monitor Closely)

• NSAIDs: can reduce diuretic efficacy and impair renal function.
• Thiazide diuretics: may cause additive electrolyte disturbances.
• Digoxin: altered serum potassium can affect digoxin toxicity.
• Corticosteroids: may counteract diuretic effect.
• Antidiabetic agents: potassium shifts may influence glucose control.