How much furosemide should be injected into a rat? - briefly
For an adult rat weighing about 250–300 g, a common intraperitoneal dose is 1–2 mg kg⁻¹ (approximately 0.25–0.6 mg per animal); when given intravenously, 0.5–1 mg kg⁻¹ is typically employed.
How much furosemide should be injected into a rat? - in detail
The recommended dose of furosemide for laboratory rats is expressed in milligrams per kilogram of body weight. The most widely cited range for a single injection is 1 – 2 mg kg⁻¹ when administered intraperitoneally (IP) or intravenously (IV). The exact amount depends on the experimental goal, the strain, age, and health status of the animal.
Typical preparation and administration steps:
- Determine animal weight. Weigh each rat individually; for example, a 250 g adult male Sprague‑Dawley weighs 0.25 kg.
- Calculate the dose.
- Low end: 1 mg kg⁻¹ × 0.25 kg = 0.25 mg.
- High end: 2 mg kg⁻¹ × 0.25 kg = 0.50 mg.
- Prepare the solution. Dissolve furosemide in sterile saline or sterile water to achieve a convenient concentration, such as 10 mg mL⁻¹. This yields 0.025 mL (low dose) or 0.050 mL (high dose) for the 250‑g rat.
- Observe maximum injection volume. For IP injections, do not exceed 2 mL kg⁻¹; for a 0.25‑kg rat, the upper limit is 0.5 mL, far above the required volume, ensuring safe administration.
- Inject using a sterile syringe with a 25‑ to 27‑gauge needle. Deliver the calculated volume slowly to avoid distress.
Additional considerations:
- Repeated dosing. If multiple administrations are planned, maintain a minimum interval of 24 hours to reduce cumulative toxicity.
- Physiological monitoring. Observe urine output, electrolyte balance, and blood pressure after injection to confirm pharmacodynamic effect.
- Ethical compliance. Follow institutional animal care guidelines and obtain appropriate approvals before dosing.
By applying the weight‑based calculation, preparing a solution at a known concentration, and respecting injection volume limits, researchers can administer furosemide to rats with reproducible dosing and minimal risk.