Bradford L McDaniel, Michael L Bentley

Prior to 2002, the incidence of acute renal failure (ARF) varied as there was no standard definition. To better understand its incidence and etiology and to develop treatment and prevention strategies, while moving research forward, the Acute Dialysis Quality Initiative workgroup developed the RIFLE (risk, injury, failure, loss, end-stage kidney disease) classification. After continued data suggesting that even small increases in serum creatinine lead to worse outcomes, the Acute Kidney Injury Network (AKIN) modified the RIFLE criteria and used the term acute kidney injury (AKI) instead of ARF. These classification and staging systems provide the clinician and researcher a starting point for refining the understanding and treatment of AKI. An important initial step in evaluating AKI is determining the likely location of injury, generally classified as prerenal, renal, or postrenal. There is no single biomarker or test that definitively defines the mechanism of the injury. Identifying the insult(s) requires a thorough assessment of the patient and their medical and medication histories. Prerenal injuries arise primarily due to renal hypoperfusion. This may be the result of systemic or focal conditions or secondary to the effects of drugs such as nonsteroidal anti-inflammatory drugs, calcineurin inhibitors (CIs), and modulators of the renin-angiotensin-aldosterone system. Renal, or intrinsic, injury is an overarching term that represents complex conditions leading to considerable damage to a component of the intrinsic renal system (renal tubules, glomerulus, vascular structures, inter-stitium, or renal tubule obstruction). Acute tubular necrosis and acute interstitial nephritis are the more common types of intrinsic renal injury. Each type of injury has several drugs that are implicated as a possible cause, with antiinfectives being the most common. Postrenal injuries that result from obstruction block the flow of urine, leading to hydronephrosis and subsequent damage to the renal parenchyma. Drugs associated with tubular obstruction include acyclovir, methotrexate, and several antiretrovirals. Renal recovery from drug-induced AKI begins once the offending agent has been removed, if clinically possible, and is complete in most cases. It is uncommon that renal replacement therapy will be needed while recovery occurs. Pharmacists can play a pivotal role in identifying possible causes of drug-induced AKI and limit their toxic effect by identifying those most likely to cause or contribute to injury. Dose adjustment is critical during changes in renal function, and the pharmacist can ensure that optimal therapy is provided during this critical time.