Pharmaceutical Calculations: Drug Calculation pdf download

 Spironolactone (Aldactone)

Uses of Spironolactone (Aldactone)

Management of edema associated with excessive aldosterone excretion or with HF that is unresponsive to other therapies; hypertension; hypokalemia, nephrotic syndrome, severe HF; primary hyperaldosteronism. Cirrhosis of liver accompanied by edema or ascites. OFF-LABEL: Treatment of edema, hypertension in children, female acne, female hirsutism. Ascites due to cirrhosis

PHARMACOTHERAPEUTIC: Aldosterone antagonist.

CLINICAL: Potassium-sparing diuretic, antihypertensive, antihypokalemic.

Precautions of Spironolactone (Aldactone)

Contraindications: Hypersensitivity to spironolactone. Acute renal insufficiency, significant impairment of renal excretory function, anuria, hyperkalemia, Addison’s disease, concomitant use with eplerenone. Cautions: Dehydration, hyponatremia, concurrent use of supplemental potassium, elderly pts, mild renal impairment, declining renal function, ACE inhibitors or angiotensin receptor blockers.

Action of Spironolactone (Aldactone)

Interferes with sodium reabsorption by competitively inhibiting action of aldosterone in distal tubule, promoting sodium and water excretion, increasing potassium retention. Therapeutic Effect: Produces diuresis, lowers B/P.

 Pharmacokinetics Spironolactone (Aldactone)

Well absorbed from GI tract (absorption increased with food). Protein binding: 91%–98%. Metabolized in liver to active metabolite. Primarily excreted in urine. Unknown if removed by hemodialysis. Half-life: 78–84 min.

Most Used 8 Calcium Channel Blockers: Action Uses Dosage Side Effect 

Lifespan considerations 

Pregnancy/Lactation: Active metabolite excreted in breast milk. Breastfeeding not recommended. Children: No age-related precautions noted. Elderly: May be more susceptible to developing hyperkalemia. Age-related renal impairment may require dosage adjustment

Interactions 

DRUG: ACE inhibitors (e.g., captopril, lisinopril), angiotensin receptor blockers (e.g., valsartan), potassium-containing medications, potassium supplements may increase risk of hyperkalemia. May increase half-life of digoxin. NSAIDs (e.g., ibuprofen, ketorolac, naproxen) may decrease antihypertensive effect. HERBAL: Avoid natural licorice (possesses mineralocorticoid activity). FOOD: Food increases absorption. LAB VALUES: May increase urinary calcium excretion, serum BUN, glucose, creatinine, magnesium, potassium, uric acid. May decrease serum sodium.

Availability (Rx) of Spironolactone (Aldactone)

Suspension, Oral: 25 mg/5 ml.

 Tablets: 25 mg, 50 mg, 100 mg.

Administration/handling of Spironolactone (Aldactone)

PO

1. Take with food to reduce GI irritation and increase absorption. 
2. Suspension: Shake well.
3.  May give with or without food (give consistently with respect to food).

 Indications/routes/dosage of Spironolactone (Aldactone)

Edema

 PO: ADULTS, ELDERLY: 25–200 mg/day as single dose or in 2 divided doses. CHILDREN: 1–3.3 mg/kg/day in divided doses q12–24h. Maximum: 100 mg. NEONATES: 1–3 mg/kg/day in divided doses q12–24h.

Hypertension

 PO: ADULTS, ELDERLY: 25–50 mg/day in 1–2 doses/day. Maximum: 100 mg. CHILDREN: 1–3.3 mg/kg/day in divided doses q12–24h. Maximum: 100 mg.

Hypokalemia

PO: ADULTS, ELDERLY: 25–100 mg/day as single dose or in 2 divided doses.

Primary Aldosteronism

PO: ADULTS, ELDERLY: 400 mg/day for 4 days up to 3–4 wks, then maintenance dose of 100–400 mg/day as single dose or in 2 divided doses.

HF

PO: ADULTS, ELDERLY: 12.5–25 mg/day adjusted based on pt response, evidence of hyperkalemia. Maximum: 50 mg.

Dosage in Renal Impairment

CrCl 50 mL/min or greater: Initially, 12.5–25 mg once daily. Maintenance: 25 mg once or twice daily. CrCl 30–49 mL/min: Initially, 12.5 mg once daily or every other day. Maintenance: 12.5–25 mg once daily. CrCl less than 30 mL/min: Not recommended.

Pharmaceutical Calculations: Drug Calculation pdf download

Side effects of Spironolactone (Aldactone)

Frequent: Hyperkalemia (in pts with renal insufficiency, those taking potassium supplements), dehydration, hyponatremia, lethargy. Occasional: Nausea, vomiting, anorexia, abdominal cramps, diarrhea, headache, ataxia, drowsiness, confusion, fever. Male: Gynecomastia, impotence, decreased libido. Female: Menstrual irregularities (amenorrhea, postmenopausal bleeding), breast tenderness. Rare: Rash, urticaria, hirsutism.

 Adverse effects/toxic reactions

Severe hyperkalemia may produce arrhythmias, bradycardia, EKG changes (tented T waves, widening QRS complex, ST segment depression). May proceed to cardiac standstill, ventricular fibrillation. Cirrhosis pts at risk for hepatic decompensation if dehydration, hyponatremia occurs. Pts with primary aldosteronism may experience rapid weight loss, severe fatigue during high-dose therapy.

 

Nursing considerations of Spironolactone (Aldactone)

 Baseline assessment 

Weigh pt; initiate strict I&O. Evaluate hydration status by assessing mucous membranes, skin turgor. Obtain baseline serum electrolytes, renal/hepatic function, urinalysis. Assess for edema; note location, extent. Check baseline vital signs, note pulse rate/regularity. 

Intervention/evaluation

 Monitor serum electrolyte values, esp. for increased potassium, BUN, creatinine. Monitor B/P. Monitor for hyponatremia: mental confusion, thirst, cold/clammy skin, drowsiness, dry mouth. Monitor for hyperkalemia: colic, diarrhea, muscle twitching followed by weakness/paralysis, arrhythmias. Obtain daily weight. Note changes in edema, skin turgor.