Diuretics in Internal Medicine: HCTZ, Furosemide, and Acetazolamide
สรุปนี้เกี่ยวกับ HCTZ, furosemide, และ acetazolamide แสดงถึงกลไกและผลต่อการรักษาที่แตกต่างกันของยา diuretics แต่ละชนิด:
- Hydrochlorothiazide (HCTZ)ใช้บ่อยในการรักษา hypertension (ความดันโลหิตสูง) มีความเสี่ยงต่อ hyponatremia (โซเดียมในเลือดต่ำ) และ hypokalemia (โพแทสเซียมในเลือดต่ำ)
- Furosemide (Lasix)เป็น loop diuretic ที่มีฤทธิ์แรง ใช้ลดภาวะน้ำเกินเฉียบพลัน เช่นใน heart failure หรือ renal failure มีผลข้างเคียงหลักคือ hypokalemia และอาจเกิด hyponatremia หรือ hypernatremia ได้ในบางกรณี
- Acetazolamide ช่วยแก้ไข metabolic alkalosis โดยปรับให้เป็นภาวะ mild metabolic acidosis ใช้ได้ในภาวะ altitude sickness (โรคแพ้ความสูง) และบางกรณีอื่น ๆ
Furosemide hypoNa > hyperNa
โดยทั่วไปแล้วในการใช้ยา Furosemide (Lasix) hyponatremia มักพบได้บ่อยกว่าการเกิด hypernatremia ถึงแม้ว่าทั้งสองภาวะจะเกิดขึ้นได้ก็ตาม ทั้งนี้กลไกหลักคือ Furosemide จะเพิ่มการขับเกลือและน้ำออกจากร่างกาย ส่งผลให้ปริมาณน้ำและโซเดียมในร่างกายลดลง ในผู้ป่วยบางรายที่มีการดื่มน้ำไม่เพียงพอหรือมีปัจจัยอื่นร่วม อาจเกิด hypernatremia จากภาวะขาดน้ำรุนแรงได้ แต่ในภาพรวมแล้ว hyponatremia ถือว่าเกิดบ่อยกว่าในทางคลินิก.
Table Recap for Drug Orders (Dose Only)
| Drug | Typical Dose |
|---|---|
| Hydrochlorothiazide (HCTZ) | 12.5–25 mg orally once daily (up to 50 mg daily as needed) |
| Furosemide (Lasix) | - Oral: 20–40 mg once or twice daily - IV: 20–40 mg IV push |
| Acetazolamide | 250–500 mg orally or IV once or twice daily (adjust per acid-base status) |
Introduction
Diuretics are essential medications in internal medicine. They help manage fluid overload, correct electrolyte imbalances, and control blood pressure. This article focuses on three commonly used diuretics—hydrochlorothiazide (HCTZ), furosemide (Lasix), and acetazolamide—explaining how they work, when they are used, their main side effects, and typical dosing.
1. Hydrochlorothiazide (HCTZ)
Mechanism of Action
- Primary Site: Distal convoluted tubule of the kidney.
- How It Works: Blocks the sodium-chloride (Na⁺/Cl⁻) transporter, leading to increased sodium and water loss in the urine.
- Effect: Lowers blood pressure and helps get rid of mild excess fluid (edema).
Key Electrolyte Effects
- Hyponatremia: Can make it harder for the body to clear excess water, raising the risk of low sodium.
- Hypokalemia: Often causes low potassium, so patients may need potassium supplements or a potassium-sparing diuretic.
- Others: Can cause low magnesium and high calcium levels.
Clinical Uses
- Hypertension: Often a first-line treatment.
- Edema: Used alongside other medications for fluid overload in heart failure, liver cirrhosis, or kidney disease.
Example Doses (Oral)
- Common Range: 12.5–25 mg once daily.
- Possible Increase: Up to 50 mg daily if needed based on patient response.
Example Order
“Hydrochlorothiazide 25 mg orally once daily;monitor potassium and sodium levels weekly.”
2. Furosemide (Lasix)
Mechanism of Action
- Primary Site: Thick ascending limb of the loop of Henle.
- How It Works: Blocks the Na⁺-K⁺-2Cl⁻ co-transporter, causing a strong diuretic effect and rapid fluid removal.
Key Electrolyte Effects
- Hypokalemia: Patients often need potassium supplements.
- Sodium Balance Issues: Can lead to either low sodium (hyponatremia) or, less commonly, high sodium if the patient becomes dehydrated.
- Others: Can cause low magnesium and low calcium; high doses or rapid IV administration can lead to hearing problems (ototoxicity).
Clinical Uses
- Fluid Overload: Helps relieve edema in heart failure, kidney failure, or liver cirrhosis.
- Severe Hypertension: Sometimes used in a hypertensive emergency along with other medications.
Example Doses
- Oral: 20–40 mg once or twice daily; can adjust as needed.
- IV: 20–40 mg IV push; may repeat or adjust to achieve the desired urine output.
Example Order
“Furosemide 40 mg IV push every 12 hours;adjust based on urine output and daily electrolytes.”
3. Acetazolamide
Mechanism of Action
- Primary Site: Proximal tubule.
- How It Works: Inhibits carbonic anhydrase, reducing bicarbonate reabsorption and causing increased bicarbonate excretion.
- Effect: Mild diuretic action, but most commonly used to adjust acid-base balance.
Key Acid-Base Effects
- Correcting Metabolic Alkalosis: Helps shift the body toward mild acidosis, balancing an elevated blood pH.
- Risk of Overcorrection: Too much can cause excessive acidosis.
Clinical Uses
- Metabolic Alkalosis: Especially useful after rapid correction of high CO₂ levels (e.g., in certain lung diseases).
- Altitude Sickness: Used for prevention and treatment.
- Glaucoma: Lowers the production of aqueous humor in the eye.
- Epilepsy (Adjunct): Sometimes used alongside other anti-seizure medications.
Example Doses
- Typical Range: 250–500 mg orally or IV once or twice daily, adjusted based on acid-base status.
Example Order
“Acetazolamide 250 mg orally twice daily;monitor serum bicarbonate and potassium.”
Summary
- Hydrochlorothiazide (HCTZ):
- Mild-to-moderate diuretic, commonly used for high blood pressure and mild fluid retention.
- Watch for low sodium and potassium levels.
- Furosemide (Lasix):
- Strong “loop” diuretic for quick reduction of fluid overload in heart, kidney, or liver disease.
- Requires close monitoring of potassium, sodium, and fluid balance.
- Acetazolamide:
- Mainly used to correct metabolic alkalosis or prevent/treat altitude sickness.
- Can cause mild metabolic acidosis; watch bicarbonate levels.
Regardless of the diuretic, regular monitoring of electrolytes (especially potassium, sodium, and magnesium), acid-base balance, and kidney function is crucial. Always adjust the dose and consider additional therapies (like potassium supplementation) based on each patient’s needs.