Medication Guide for Hydrochlorothiazide

Drug Classification

Hydrochlorothiazide is classified as a thiazide diuretic. It works by inhibiting sodium reabsorption in the distal tubules of the kidneys, leading to increased excretion of sodium and water.

Indications for Use

Hydrochlorothiazide is indicated for the treatment of hypertension. It is used as an adjunctive therapy in edema associated with congestive heart failure, hepatic cirrhosis, and corticosteroid and estrogen therapy. It is also useful in edema due to various forms of renal dysfunction, including nephrotic syndrome, acute glomerulosclerosis, and chronic renal failure.

Dosage Forms

Hydrochlorothiazide is available in tablet and capsule forms. Common dosages include 12.5 mg, 25 mg, and 50 mg tablets and capsules.

Mechanism of Action

Hydrochlorothiazide works by inhibiting the sodium-chloride symporter in the distal convoluted tubules of the kidneys. This leads to increased excretion of sodium and chloride ions, promoting diuresis and fluid loss. The resultant decrease in blood volume lowers blood pressure.

Pharmacokinetics

Hydrochlorothiazide is well absorbed from the gastrointestinal tract. It has a relatively rapid onset of action, typically within two hours. Peak plasma concentration is reached in approximately four hours. The drug is excreted primarily unchanged in the urine.

Administration Guidelines

Hydrochlorothiazide should be taken orally, usually once daily in the morning to avoid nocturia. It can be taken with or without food. Consistent daily intake time is recommended for optimal results. Patients should follow their prescribed dosage regimen strictly.

Interaction with Foods

Grapefruit and grapefruit juice may interact with hydrochlorothiazide. Patients are advised to avoid these to prevent potential adverse effects. A diet high in potassium-rich foods may be recommended to counteract hypokalemia.

Interaction with Other Drugs

Hydrochlorothiazide may interact with other antihypertensives, increasing their hypotensive effects. Nonsteroidal anti-inflammatory drugs (NSAIDs) can reduce the diuretic effect. Concurrent use with corticosteroids can elevate the risk of hypokalemia.

Special Populations

Renal impairment may necessitate dosage adjustments. Elderly patients are more susceptible to orthostatic hypotension. Pediatric use should be carefully considered with adjusted dosages based on body weight. Pregnant and lactating women should consult their healthcare provider before use.

Effect on Electrolytes

Hydrochlorothiazide can cause electrolyte imbalances like hypokalemia, hyponatremia, and hypercalcemia. Regular monitoring of serum electrolytes is recommended. Symptoms of electrolyte imbalance include muscle weakness, cramps, fatigue, and irregular heartbeats.

Storage Conditions

Hydrochlorothiazide should be stored at room temperature, away from moisture and heat. Keep the medication in its original container and out of reach of children to prevent accidental ingestion.

Overdose Management

Symptoms of overdose include severe dehydration, electrolyte imbalance, hypotension, and tachycardia. Immediate medical attention is required. Treatment involves supportive measures like fluid and electrolyte replacement and symptomatic management.

Laboratory Tests

Baseline and periodic monitoring of serum electrolytes, renal function, and complete blood count (CBC) are advised. Blood pressure should be regularly checked to gauge therapeutic efficacy and adjust dosage if needed.

Potential Side Effects

Common side effects include dizziness, headache, weakness, and gastrointestinal disturbances. Rare but serious side effects include pancreatitis, jaundice, and severe skin reactions. Patients should report any unusual symptoms to their healthcare provider promptly.

Patient Monitoring

Patients on hydrochlorothiazide therapy should be regularly monitored for signs of electrolyte imbalance, kidney function, and hydration status. Blood pressure should be routinely checked, ideally by the patient at home as well as during clinic visits.

Cost and Availability

Hydrochlorothiazide is a widely available generic medication, making it relatively affordable. It is covered by most insurance plans, including Medicare. Brand-name versions may be priced higher but offer the same therapeutic benefits.

Patient Education

Patients should be educated on the importance of adhering to their treatment regimen, potential side effects, and signs of electrolyte imbalance. They should be advised to report any adverse reactions or changes in their condition to their healthcare provider immediately.

Alternative Therapies

Alternative diuretics include loop diuretics such as furosemide and potassium-sparing diuretics like spironolactone. Each class has distinct mechanisms and side effect profiles. Consultation with a healthcare professional is essential for appropriate selection.