Drug Guide
Amiloride Hydrochloride and Hydrochlorothiazide
Classification
Therapeutic: Antihypertensive, Diuretic
Pharmacological: Potassium-sparing diuretic and Thiazide diuretic combination
FDA Approved Indications
- Hypertension
- Edema associated with heart failure, hepatic impairment, or renal disease
Mechanism of Action
Amiloride inhibits sodium channels in the distal tubules, decreasing sodium reabsorption and potassium excretion. Hydrochlorothiazide inhibits sodium reabsorption in the distal tubules, leading to diuresis. The combination balances potassium levels while providing antihypertensive effects.
Dosage and Administration
Adult: Typically, 5-10 mg of amiloride and 25-50 mg of hydrochlorothiazide once daily or in divided doses.
Pediatric: Use under medical supervision; dosing varies based on age and condition.
Geriatric: Start with lower doses due to increased sensitivity to diuretics.
Renal Impairment: Use with caution; dosage adjustments may be necessary.
Hepatic Impairment: Use cautious in hepatic impairment; monitor closely.
Pharmacokinetics
Absorption: Well absorbed from the gastrointestinal tract.
Distribution: Widely distributed; crosses the placenta, appears in breast milk.
Metabolism: Amiloride and hydrochlorothiazide undergo minimal metabolism.
Excretion: Renally excreted; active compounds in urine.
Half Life: Approximately 6-9 hours for amiloride; hydrochlorothiazide varies between 6-15 hours.
Contraindications
- Anuria
- Electrolyte imbalances (hyperkalemia, hyponatremia)
- Significant renal impairment
Precautions
- Monitor serum potassium, sodium, renal function; use with caution in hepatic disease, elderly, diabetic patients, and patients on other potassium-sparing drugs.
Adverse Reactions - Common
- Hyperkalemia (Uncommon)
- Hyponatremia (Uncommon)
- Dizziness, headache (Common)
- Gastrointestinal disturbances (Common)
Adverse Reactions - Serious
- Electrolyte imbalances (hyperkalemia, hyponatremia) (Serious, requires monitoring)
- Nephrolithiasis (Rare)
- Allergic reactions including rash, urticaria (Rare)
Drug-Drug Interactions
- ACE inhibitors, ARBs (risk of hyperkalemia), other potassium-sparing diuretics, lithium (toxicity), digoxin
Drug-Food Interactions
- Potassium-rich foods (to prevent hyperkalemia)
Drug-Herb Interactions
- Potassium-containing supplements, herbal supplements affecting potassium levels
Nursing Implications
Assessment: Monitor blood pressure, serum electrolytes, renal function
Diagnoses:
- Risk for electrolyte imbalance,
- Risk for hypotension
Implementation: Administer with food to minimize gastrointestinal upset; monitor electrolytes regularly.
Evaluation: Assess blood pressure response, electrolyte levels, and signs of adverse effects.
Patient/Family Teaching
- Advise patient to maintain adequate potassium intake unless instructed otherwise.
- Report signs of hyperkalemia (muscular weakness, irregular heartbeat) or dehydration.
- Take medication exactly as prescribed and do not double doses.
Special Considerations
Black Box Warnings:
- Potential for hyperkalemia, especially in patients with renal impairment or concurrent use of other potassium-elevating drugs.
Genetic Factors: Sensitivity to diuretics varies; ethnic differences in response observed.
Lab Test Interference: May cause false elevation of serum uric acid and calcium levels.
Overdose Management
Signs/Symptoms: Severe electrolyte disturbances, dehydration, hypotension, dizziness.
Treatment: Discontinue medication, administer supportive care, correct electrolyte imbalances, monitor cardiovascular status.
Storage and Handling
Storage: Store at room temperature, away from moisture and heat.
Stability: Stable under recommended storage conditions for the shelf life as indicated by the manufacturer.