Polymyxin B in Patients With Renal Impairment: Is It Necessary to Adjust Dose?

In patients with renal impairment, drugs undergo significant changes in their pharmacokinetics, which require dosage adjustments to ensure safe and effective therapy.
Reduced renal clearance and elimination rate are common outcomes of renal impairment. These alterations lead to a prolonged elimination half-life and an altered apparent volume of distribution for drugs. As a result, dosage adjustments are typically necessary to maintain optimal drug levels in the body.
However, dosage adjustments...

Renal dysfunction significantly impairs the renal clearance of drugs, leading to potential complications in drug therapy. Renal failure, which can be caused by various factors, poses a significant challenge in the elimination of drugs from the body.
One condition associated with renal failure is uremia. Uremia is characterized by impaired glomerular filtration and fluid accumulation in the body. This condition hinders the renal clearance of drugs, resulting in drug accumulation and potential...

Active tubular secretion is a robust, energy-demanding process that utilizes carrier systems to transport drugs into renal tubules. The active renal secretion systems include the organic anion transporter (OAT) for weak acids and the organic cation transporter (OCT) for weak bases. Structurally similar drugs can compete for the same transporter, potentially leading to drug accumulation and toxicity. However, this principle can be exploited therapeutically. One example is probenecid (Probalan),...

As primary excretory organs, the kidneys maintain homeostasis by removing waste substances from the bloodstream. They comprise over a million units called nephrons, which serve as the kidney's functional units.
A nephron consists of two primary structures: the renal corpuscle and the renal tubule. The renal corpuscle contains the glomerulus, a network of capillaries where the first step of renal excretion, glomerular filtration, occurs. Blood pressure forces water, ions, and small molecules...

The elimination half-life and drug clearance of drugs following nonlinear kinetics can vary with dosage. The Michaelis-Menten parameters and drug concentration influence these factors. As the dose increases, the elimination half-life tends to lengthen, resulting in a reduction in clearance and a disproportionately larger area under the curve. The total clearance can be derived from the Michaelis-Menten equation for drugs following a one-compartment model.
A study on guinea pigs examined the...

Once the process of glomerular filtration is completed, blood carrying unfiltered drug molecules traverses through efferent arterioles and makes its way into the peritubular capillaries in the proximal tubule. A variety of carriers play a pivotal role in actively secreting drugs from these peritubular capillaries into the tubular fluid. The organic anion transporter transfers acidic drugs, against an electrochemical gradient, from the peritubular capillaries into the renal tubule cells and...