Renal clearance intravenous bolus

Pharmacokinetics The bioavailability of a subcutaneous dose of epoetin alfa, relative to an intravenous bolus, has been estimated at 22% to 31%. The elimination half-life of epoetin alfa after an intravenous dose is 6 to 13 hours in patients with chronic renal failure. Mean clearance ranges from 0.032 to 0.055 ml/min per kg. The apparent half-life after a subcutaneous dose is 27 hours. Volume of distribution estimates range from 0.021 to 0.0631/kg. 

GFR and RPF can be measured without collection of urine by measuring the disappearance of the appropriate tracers from the blood over time (plasma clearance). In this technique, precise amounts of tracers are injected intravenously as a bolus and subsequent serial samples at precise intervals are collected. The disappearance of the tracer from the blood used to calculate the renal clearance (Bailey et al. 1970 Ronnhedh et al. 1996). 

Finally, the method used to calculate the volume of distribution may be influenced by renal insufficiency. The three most commonly used volume of distribution terms are volume of the central compartment (Ec), volume of the terminal phase (E, E jea). and volume of distribution at steady state (Eis). The central compartment volume is calculated as the intravenous bolus dose divided by the initial plasma concentration. E for many drugs approximates extracellular fluid volume and thus may be increased or decreased by shifts in this physiologic volume. Renal insufficiency, especially oliguric acute renal failure, is often accompanied by fluid overload and a resultant increased Ec due to reduced renal elimination of water and sodium. Uaiea Or E is Calculated as the total body clearance divided by the terminal elimination rate constant (k or /3). This volume term represents the proportionality constant between plasma concentrations in the terminal elimination phase and the amount of drug remaining in the body. E is affected by both distribution characteristics, as well as by the elimination rate constant. The third volume term, the steady-state volume of distribution (Ess), is calculated as (AUMC x dose)/AUC , where AUMC is the area under the first moment of the concentrationtime curve and AUC is the area under the concentration-time curve... 

Renal clearance of intravenous bolus of drug (one compartment]... 

Renal impairment has been associated with the use of intravenous aciclovir. Transient increases in serum creatinine and urea have been observed in 14% of patients treated with bolus injections (16). These are related to crystal formation in the lower renal tubules when the solubility of aciclovir in urine is exceeded. Slow (1-hour) intravenous infusion and adequate hydration are therefore mandatory. Bolus doses are to be avoided. Dosage modifications for patients with renal insufficiency are based on creatinine clearance (4). 

IL-2 has been used in the treatment of sohd tumors such as metastatic melanoma, metastatic renal cell carcinoma, and colorectal carcinoma. Interleukin-2 infusions are associated with significant dose-dependent toxicity characterized by fevers, malaise, nausea, vomiting, diarrhea, hepatic dysfunction, pulmonary edema, somnolence, confusion, dysrhythmias, myocardial infarction, hematopoietic suppression, and renal insufficiency [10]. IL-2 has a short serum half-life of 6-10 min and a clearance of 30-60 min after bolus intravenously infusion [11]. Resultant toxicity is generally transient and reversible. It is possible that IL-2 induced renal failure only occurs in the setting of profound hypotension, prior volume depletion, concurrent administration of potentially nephrotoxic drugs, or the presence of underlying renal disease. 

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