Pharmacology Of Aminohippurate

Indication	Used to measure effective renal plasma flow (ERPF) and to determine the functional capacity of the tubular excretory mechanism.
Pharmacodynamics	Aminohippurate (p-aminohippuric acid, PAH, PAHA) is the glycine amide of p-aminobenzoic acid. It is filtered by the glomeruli and is actively secreted by the proximal tubules. At low plasma concentrations (1.0 to 2.0 mg/100 mL), an average of 90 percent of aminohippurate is cleared by the kidneys from the renal blood stream in a single circulation. It is ideally suited for measurement of ERPF since it has a high clearance, is essentially nontoxic at the plasma concentrations reached with recommended doses, and its analytical determination is relatively simple and accurate. Aminohippurate is also used to measure the functional capacity of the renal tubular secretory mechanism or transport maximum (TmPAH). This is accomplished by elevating the plasma concentration to levels (40-60 mg/100 mL) sufficient to saturate the maximal capacity of the tubular cells to secrete aminohippurate. Inulin clearance is generally measured during TmPAH determinations since glomerular filtration rate (GFR) must be known before calculations of secretory Tm measurements can be done.
Mechanism of action	Aminohippurate is filtered by the renal glomeruli and secreted into the urine by the proximal tubules. By measuring the amount of drug in the urine it is possible to determine functional capacity and effective renal plasma flow.
Absorption	Not Available
Volume of distribution	Not Available
Protein binding	Not Available
Metabolism	Not Available
Route of elimination	Not Available
Half life	Not Available
Clearance	Not Available
Toxicity	The intravenous LD50 in female mice is 7.22 g/kg.