Urinary excretion is a complex and significant route for the elimination of many drugs from the body. The functional units of the kidney, the nephrons, determine the degree of renal drug elimination through the balance of filtration, secretion and reabsorption (Figure 1). An understanding of the physiological events occuring within the nephron is useful, then, in estimating drug clearance and predicting a variety of clinically significant drug interactions. buy asthma inhalers
A great deal of information concerning the mechanism of drug transport systems has been acquired over the past few years. Much like a schoolyard playground is crowded with active children, the nephron is crowded with a number of drug transport systems full of activity. Transporter protein science is a rapidly progressing field of pharmacology and new transporter proteins or subtypes are discovered regularly. Because the molecular approach in this area is relatively new and the full clinical implications are not yet known, this paper aims not to summarize the complete body of research to date, but rather to present a quick overview of several of the major transport systems responsible for the renal elimination of drugs. Furthermore an attempt has been made to provide a clinical context for the discovery of novel renal transport mechanisms using P-glycoprotein (P-gp) as an example.