hydrochlorothiazide

hydrochlorothiazide

(hye droe klor oh thye' a zide)

Apo-Hydro (CAN), Esidrix, Ezide, HydroDIURIL, Microzide Capsules, Oretic

Pregnancy Category B

Drug class

Thiazide diuretic

Therapeutic actions

Inhibits reabsorption of sodium and chloride in distal renal tubule, increasing the excretion of sodium, chloride, and water by the kidney.

Indications

·        Adjunctive therapy in edema associated with CHF, cirrhosis, corticosteroid, and estrogen therapy; renal dysfunction

·        Hypertension as sole therapy or in combination with other antihypertensives

·        Unlabeled uses: Calcium nephrolithiasis alone or with amiloride or allopurinol to prevent recurrences in hypercalciuric or normal calciuric patients; diabetesinsipidus, especially nephrogenic diabetes insipidus; osteoporosis

Contraindications and cautions

·        Contraindicated with allergy to thiazides, sulfonamides; fluid or electrolyte imbalance; renal disease (can lead to azotemia); liver disease (risk of hepatic coma); anuria.

·        Use cautiously with gout (risk of attack); SLE; glucose tolerance abnormalities, diabetes mellitus; hyperparathyroidism; manic-depressive disorder (aggravated by hypercalcemia); pregnancy; lactation, elevated triglyceride levels.

Available forms

Tablets—25, 50, 100 mg; solution—50 mg/5 mL; capsules—12.5 mg

Dosages

ADULTS

·        Edema: 25–200 mg daily PO until dry weight is attained. Then, 25–100 mg daily PO or intermittently, up to 200 mg/day.

·        Hypertension: 12.5–50 mg PO.

·        Calcium nephrolithiasis: 50 mg daily or bid PO.

PEDIATRIC PATIENTS

2–12 yr: 37.5–100.0 mg/day in 2 doses.

General guidelines: 2.2 mg/kg/day PO in 2 doses.

6 mo–2 yr: 12.5–37.5 mg/day in 2 doses.

< 6 mo: Up to 3.3 mg/kg/day in 2 doses.

Pharmacokinetics

Route	Onset	Peak	Duration
Oral	2 hr	4–6 hr	6–12 hr

Metabolism: Hepatic; T_1/2: 5.6–14.8 hr

Distribution: Crosses placenta; enters breast milk

Excretion: Urine

Adverse effects

·        CNS: Dizziness, vertigo, paresthesias, weakness, headache, drowsiness, fatigue

·        CV: Orthostatic hypotension, venous thrombosis, volume depletion, cardiac arrhythmias, chest pain

·        Dermatologic: Photosensitivity, rash, purpura, exfoliative dermatitis, hives, alopecia

·        GI: Nausea, anorexia, vomiting, dry mouth, diarrhea, constipation, jaundice, hepatitis, pancreatitis

·        GU: Polyuria, nocturia, impotence, loss of libido

·        Hematologic: Leukopenia, thrombocytopenia, agranulocytosis, aplastic anemia, neutropenia

·        Other: Muscle cramps and muscle spasms, fever, gouty attacks, flushing, weight loss, rhinorrhea, electrolyte imbalances, hyperglycemia

Interactions

Drug-drug

·        Altered electrolytes with loop diueretics, amphotericin B, corticosteroids

·        Increased neuromuscular blocking effects and respiratory depression with nondepolarizing muscle relaxants

·        Decreased absorption with cholestyramine, colestipol

·        Increased risk of cardiac glycoside toxicity if hypokalemia occurs

·        Increased risk of lithium toxicity

·        Decreased effectiveness of antidiabetic drugs

Drug-lab test

·        Decreased PBI levels without clinical signs of thyroid disturbance

Nursing considerations

Assessment

·        History: Allergy to thiazides, sulfonamides; fluid or electrolyte imbalance; renal or liver disease; gout; SLE; glucose tolerance abnormalities, diabetes mellitus; hyperparathyroidism; manic-depressive disorders; lactation, pregnancy

·        Physical: Skin color, lesions, edema; orientation, reflexes, muscle strength; pulses, baseline ECG, BP, orthostatic BP, perfusion; R, pattern, adventitious sounds; liver evaluation, bowel sounds, urinary output patterns; CBC, serum electrolytes, blood glucose, LFTs, renal function tests, serum uric acid, urinalysis

Interventions

·        Give with food or milk if GI upset occurs.

·        Mark calendars or provide other reminders of drug for alternate day or 3–5 days/wk therapy.

·        Reduce dosage of other antihypertensives by at least 50% if given with thiazides; readjust dosages gradually as BP responds.

·        Administer early in the day so increased urination will not disturb sleep.

·        Measure and record weights to monitor fluid changes.

Teaching points

·        Record intermittent therapy on a calendar, or use prepared, dated envelopes. Take drug early so increased urination will not disturb sleep. Drug may be taken with food or meals if GI upset occurs.

·        Weigh yourself on a regular basis, at the same time and in the same clothing; record weight on your calendar.

·        You may experience these side effects: Increased volume and frequency of urination; dizziness, feeling faint on arising, drowsiness (avoid rapid position changes; hazardous activities, like driving; and alcohol); sensitivity to sunlight (use sunglasses, wear protective clothing, or use a sunscreen); decrease in sexual function; increased thirst (sucking on sugarless lozenges and frequent mouth care may help); gout attack (report any sudden joint pain).

·        Report weight change of more than 3 pounds in 1 day, swelling in your ankles or fingers, unusual bleeding or bruising, dizziness, trembling, numbness, fatigue, muscle weakness or cramps.

Adverse effects in Italic are most common; those in Bold are life-threatening.