1Assistant Professor Medical Lab science, Maulana Azad National Urdu University Telangana Hyderabad.
2DrNB Resident, Department of Nephrology, Government Medical College Srinagar.
3Assistant Professor, Department of Anesthesia and Operation Theatre, Lyallpur Khalsa College Technical Campus, Jalandhar, Punjab
Chronic kidney disease (CKD) is a notable long-term complication seen in individuals who have undergone cardiac surgery, especially those receiving heart valve replacements. The postoperative care of these patients frequently necessitates the extended use of several medications, including antibiotics that can harm the kidneys, to avert and manage infections. Prolonged contact with such drugs may lead to a gradual decline in kidney function. This review article examines the occurrence and advancement of chronic kidney disease in patients who have been treated with nephrotoxic antibiotics following cardiac operations. Observations from clinical cases reveal that numerous patients maintain stable conditions shortly after surgery; however, they often experience renal impairment two to three years later. There is typically a gradual increase in serum creatinine levels, frequently surpassing 2.0 mg/dL after three years, alongside an increase in blood urea and serum uric acid levels, which indicates a decline in renal clearance. These biochemical changes generally worsen annually, with serum creatinine rising about 1 mg/dL each year. Eventually, creatinine levels may escalate to between 4.5 and 5.5 mg/dL, signifying severe kidney damage. The combined nephrotoxic impact of antibiotics, along with other postoperative treatments, existing health issues, and prolonged changes in hemodynamics, significantly contribute to the onset of CKD. In advanced cases, patients often progress to end-stage renal disease (ESRD), marked by consistently high levels of serum creatinine, urea, and uric acid, ultimately necessitating renal replacement options such as dialysis or kidney transplantation. This review underscores the critical need for early identification of renal dysfunction, prudent and judicious use of nephrotoxic antibiotics, consistent monitoring of renal function indicators, and prompt referral to nephrology for patients post-cardiac surgery. Employing preventive measures and tailored medication management may help alleviate the long-term impact of CKD and enhance patient outcomes.
The idea of nephrotoxicity first appeared in scientific writings in the early 1900s, primarily through research that explored the impact of nephrotoxic serum on kidney tissue. One of the earliest recognized instances of drug-related nephrotoxicity was documented by Bell M.E. in 1933, highlighting kidney damage from cystine. Over the following decades, a variety of scientists studied the detrimental effects that different medications can have on kidney structure and function. However, the recognition of kidney damage can be traced back even further to Hippocrates, who noted that kidney performance and urine production fluctuated with the consumption of external substances such as food and beverages.
In contemporary medicine, nephrotoxicity has emerged as a vital area of research and plays a crucial role in assessing the safety and effectiveness of both existing and newly introduced pharmaceuticals. Nephrotoxicity refers to the impairment of kidney function or structure due to exposure to medications, toxins, or diagnostic substances. Renal injury induced by drugs may negatively impact glomerular and tubular functions, interfere with blood pressure regulation, and modify the endocrine roles of the kidneys. The structural damage can vary from minor microscopic changes in renal tissue to significant morphological transformations like renal atrophy.
The kidneys, which are two essential organs, carry out critical tasks necessary for homeostasis, such as managing fluid and electrolyte equilibrium, osmolarity, blood pressure, acid-base balance, hormone metabolism, and the excretion of metabolic waste and xenobiotics. Each kidney houses around one million nephrons to ensure optimal filtration and metabolic processes. Despite their efficiency, the kidneys are especially susceptible to toxic damage due to several factors, including high blood flow, a large number of xenobiotic transporters, active metabolic enzymes within the kidneys, and the concentration of filtered substances in the renal tubules during urine production. Furthermore, the kidneys have limited regeneration capabilities, and nephron loss progresses due to injury, illness, or aging. After 40 years of age, the functional nephron count declines by roughly 10% every decade.
Nephrotoxicity resulting from medications is generally divided into two categories: dose-dependent toxicity and idiosyncratic toxicity. Dose-dependent nephrotoxicity can frequently be mitigated by decreasing the medication dosage and treatment duration, particularly in patients with existing risk factors like chronic renal insufficiency or simultaneous use of other nephrotoxic substances. Conversely, idiosyncratic reactions are unpredictable, vary from patient to patient, and are not related to the drug dosage or its pharmacological mechanism. In these instances, the best preventive measure is to avoid the offending medication.
Renal injury from nephrotoxic agents can present in several clinical forms, such as acute kidney injury (AKI), chronic kidney disease (CKD), acute interstitial nephritis, and proteinuria linked to glomerular damage. AKI is particularly common among hospitalized individuals, occurring in as many as 60% of admissions to intensive care units (ICUs), with nephrotoxic drugs responsible for about 25% of these cases. While AKI can be reversible, it is often associated with long-term subclinical renal damage that may progress to CKD and lead to systemic complications like hypertension, type 2 diabetes mellitus, and heart failure.
Chronic kidney disease (CKD) poses a significant and increasingly urgent challenge to public health on a global scale, with estimates suggesting a prevalence between 3% and 18% across various populations. A major barrier in managing severe infections, cancers, and other related conditions is nephrotoxicity, which limits the clinical application of numerous effective medications. Even with this concern, nephrotoxic drugs are frequently prescribed due to a lack of alternatives, cost considerations, and a general lack of awareness among healthcare providers regarding the risks to renal health compared to the therapeutic advantages these drugs offer.
Our current insights into the mechanisms that lead to drug-induced nephrotoxicity are still not fully developed. There is a need for further investigation to clarify these intricate pathways and to create sensitive and precise biomarkers that can detect kidney damage early on. Timely recognition of nephrotoxicity could help avert irreversible kidney harm and enhance patient outcomes. Consequently, this review examines commonly prescribed nephrotoxic medications, their mechanisms of inducing renal injury, and recent developments in biomarkers that facilitate the early identification of drug-related kidney damage. A thorough review of the available evidence could inform future large-scale studies intended to enhance drug safety, mitigate nephrotoxicity, and support the creation of new therapeutic and protective approaches.
Cardiac surgeries have significantly enhanced both survival rates and quality of life for individuals with cardiovascular conditions. Improvements in surgical methods, anesthesia, and post-operative care have resulted in better short-term results. However, there is a growing acknowledgment of the long-term complications that can arise following cardiac operations, with renal dysfunction and CKD being significant contributors to morbidity and mortality.
Patients recovering from cardiac surgery frequently require extensive and intricate pharmacological management, which includes the use of antibiotics, anticoagulants, diuretics, and other supportive treatments. Nephrotoxic antibiotics are often administered post-surgery to prevent or manage infections such as those at surgical sites, infective endocarditis, and sepsis. Although these medications are critical for survival, their prolonged or repeated administration can negatively impact kidney function, particularly in individuals with existing risk factors.
Chronic kidney disease is marked by a slow, irreversible decline in kidney function, indicated by persistent increases in serum creatinine, blood urea, and uric acid levels. In many patients who have undergone cardiac surgery, renal impairment may not be immediately noticeable but can develop gradually over a 2–3-year timeframe post-surgery. Initially, patients may exhibit a mild elevation in serum creatinine (>2.0 mg/dL), which tends to worsen over the following years. This gradual decline can ultimately lead to advanced CKD or end-stage renal disease (ESRD), necessitating interventions such as dialysis or kidney transplantation.
Multiple factors influence the development of CKD in these patients. Nephrotoxic antibiotics play a role through direct toxicity to kidney tubules, alterations in renal blood flow, and the cumulative effects of drug exposure over time. Furthermore, variables such as older age, extended hospital stays, recurrent infections, polypharmacy, and underlying conditions like hypertension or diabetes, alongside postoperative hemodynamic instability, significantly heighten the risk of long-term kidney damage. The interplay of these elements accelerates the progression of renal dysfunction.
Despite the increasing awareness of CKD as a delayed complication following cardiac surgery, there has been limited focus on the long-term incidence and development specifically associated with the use of nephrotoxic antibiotics. Identifying patients at risk early, judiciously choosing and dosing antibiotics, and consistently monitoring renal function are vital steps in preventing or slowing the advancement of chronic kidney disease (CKD). This review focuses on the frequency, biochemical progression, and clinical results of CKD in individuals receiving nephrotoxic antibiotics after cardiac surgery, particularly those undergoing heart valve replacement. Grasping these connections is key to enhancing postoperative care strategies and alleviating the long-term renal impact on this susceptible group of patients.
Mechanisms of Nephrotoxic Drug Injury
Nephrotoxic medications can harm the kidneys by disrupting normal renal function and structure through various pathways. The kidneys are especially prone to drug-related toxicity due to their high perfusion, ability to concentrate substances, and active transport mechanisms in renal tubules. In patients post-cardiac surgery, extended exposure to nephrotoxic antibiotics, coupled with hemodynamic stress and multiple medications, greatly raises the likelihood of developing chronic kidney disease.
1. Direct Damage to Renal Tubules
A number of nephrotoxic antibiotics adversely affect renal tubular epithelial cells directly, particularly in the proximal tubules. Agents like aminoglycosides and vancomycin accumulate in tubular cells via endocytosis, resulting in mitochondrial dysfunction, hindrance of protein synthesis, and disruption of cellular membranes. This leads to either apoptosis or necrosis of tubular cells, decreased reabsorption, and impaired elimination of metabolic waste. Ongoing tubular injury is associated with rising serum levels of creatinine, urea, and uric acid.
2. Changes in Renal Blood Flow
Some medications disrupt renal blood circulation by influencing the mechanisms of vasoconstriction and vasodilation within the kidneys. Nephrotoxic substances may inhibit prostaglandin production or trigger vasoconstrictor pathways, leading to diminished glomerular perfusion and a lower glomerular filtration rate (GFR). In patients who have undergone cardiac surgery, compromised cardiac output and unstable blood pressure worsen these hemodynamic alterations, accelerating renal injury.
3. Inflammation and Oxidative Stress
Nephrotoxic drugs promote the formation of reactive oxygen species (ROS), which leads to oxidative stress in kidney tissues. This increased oxidative damage incites inflammatory responses, resulting in the release of cytokines, infiltration of leukocytes, and additional damage to glomerular and tubular structures. Ongoing inflammation fosters interstitial fibrosis and tubular atrophy, which are significant pathological features associated with chronic kidney disease.
4. Fibrosis in the Tubulointerstitial Area
Long-term or repeated exposure to nephrotoxic agents results in ongoing injury and maladaptive repair mechanisms. The activation of fibroblasts and excessive accumulation of extracellular matrix proteins lead to tubulointerstitial fibrosis. This irreversible damage reduces nephron number and progressively impairs kidney function, ultimately culminating in advanced CKD and end-stage renal disease.
5. Crystal-Related Kidney Damage
Certain medications or their metabolites can crystallize within renal tubules, causing physical obstruction and localized inflammation. This results in tubular blockage, heightened intratubular pressure, and decreased glomerular filtration. Injury caused by crystals exacerbates renal dysfunction and leads to increasing serum levels of creatinine and urea.
6. Immune-Mediated Damage
Some nephrotoxic drugs can provoke immune-mediated reactions such as acute interstitial nephritis. These drug-induced hypersensitivity responses involve the infiltration of eosinophils, lymphocytes, and plasma cells into the renal interstitium, resulting in inflammation and swelling. If not recognized or if they occur repeatedly, immune-mediated damage may lead to chronic interstitial nephritis and lasting renal impairment.
7. Combined and Cumulative Effects of Medications on Kidney Function
Patients recovering from cardiac surgery frequently receive several drugs that may harm the kidneys, such as antibiotics, diuretics, and contrast agents. The simultaneous use of these medications can create a synergistic effect, increasing the risk of renal toxicity even when administered at therapeutic levels. Additionally, long-term cumulative exposure significantly contributes to the development of chronic kidney disease (CKD) that may manifest years after the surgical procedure
Drug-wise Nephrotoxic Antibiotics Table (1.1)
|
Drug Class |
Common Drugs Used Post Cardiac Surgery |
Mechanism of Nephrotoxicity |
Type of Renal Injury |
Risk Factors |
|
Beta-lactams |
Piperacillin-Tazobactam, Cefepime |
Immune-mediated hypersensitivity reaction |
Acute interstitial nephritis |
Repeated exposure, allergy history |
|
Antifungals |
Amphotericin B |
Increased membrane permeability → electrolyte imbalance and tubular damage |
Tubular necrosis, reduced GFR |
High cumulative dose, dehydration |
|
Fluoroquinolones |
Ciprofloxacin, Levofloxacin |
Crystal precipitation, oxidative stress |
Crystal nephropathy |
Dehydration, high dose |
|
Sulfonamides |
Trimethoprim-Sulfamethoxazole |
Crystal deposition, inhibition of tubular secretion of creatinine |
Pseudo-rise in creatinine, tubular obstruction |
Dehydration, acidic urine |
|
Combination Therapy |
Vancomycin + Piperacillin-Tazobactam |
Synergistic nephrotoxicity |
Accelerated CKD progression |
Polypharmacy, long hospital stay |
Clinical Linkage to Laboratory Findings
In patients who have undergone cardiac surgery, the progression of kidney toxicity is evidenced by specific changes in renal biochemical markers. The relationship between medication exposure and lab results is summarized below:
Serum Creatinine
An early sign of declining glomerular filtration rate (GFR)
Typically exceeds 2.0 mg/dL within 2 to 3 years post-surgery
Annual increase of about 1 mg/dL, indicating chronic deterioration
Levels between 4.5 and 5.5 mg/dL suggest advanced CKD or end-stage renal disease (ESRD)
Blood Urea
Increased levels due to diminished renal clearance
Indicates impaired tubular reabsorption and filtration
Ongoing elevation correlates with worsening azotemia
Serum Uric Acid
Heightened levels due to impaired excretion
Reflects compromised tubular secretion
Related to crystal nephropathy and oxidative damage
Estimated GFR (eGFR)
Gradual decline aligns with rising creatinine levels
eGFR below 60 mL/min/1.73 m² indicates CKD
eGFR below 15 mL/min/1.73 m² points to ESRD
Urinalysis Results
Mild proteinuria
Presence of tubular casts
Crystalluria (related to medication use)
Clinical Outcome Associations
Consistent elevations in creatinine, urea, and uric acid over time are strongly linked to:
Advancement from CKD to ESRD
The need for dialysis
Requirement for kidney transplantation
Pathophysiological Mechanisms Behind Nephrotoxic Antibiotic-Induced CKD in Cardiac Surgery Patients
The following illustration depicts the process of kidney injury caused by nephrotoxic antibiotics in individuals who have undergone cardiac surgery. After surgery, patients often receive extended antibiotic treatment to prevent or manage infections. These harmful drugs enter the systemic circulation, are filtered by the kidneys, and accumulate in renal tubular epithelial cells due to significant renal blood flow and active transport mechanisms within the tubules.
The buildup of these medications causes direct injury to tubular cells through oxidative stress, dysfunction of mitochondria, and inflammatory responses. Concurrently, changes in renal blood flow lead to reduced glomerular perfusion, resulting in a lower glomerular filtration rate. Ongoing damage triggers maladaptive repair mechanisms, leading to tubulointerstitial inflammation and fibrosis.
Over time, continuous nephron loss results in sustained increases in serum creatinine, blood urea, and uric acid levels. Ongoing exposure and cumulative toxicity ultimately lead to chronic kidney disease, progressing to end-stage renal disease that requires dialysis or kidney transplantation.
Biomarkers for Early Detection and Prevention of Nephrotoxic Effects
Evaluating kidney function is crucial for the prompt detection and prevention of drug-related renal injury. A variety of biomarkers exist for tracking nephrotoxicity, with the glomerular filtration rate (GFR) being the most commonly utilized measure of kidney function overall. GFR indicates how effectively the kidneys filter blood and aids in assessing both the status of renal function and the progression of kidney disease. Typically, GFR values fall between 100 and 130 mL/min/1.73 m² under normal circumstances. While precise determination of GFR can be achieved through exogenous markers like inulin, EDTA, and iohexol, these techniques are often expensive, technically intricate, and not routinely applicable in everyday clinical settings.
As a result, endogenous biomarkers are preferred in practice. Serum creatinine and blood urea nitrogen are the parameters most frequently monitored; nevertheless, cystatin C is gaining recognition as a more sensitive indicator of early kidney impairment. The relationship between GFR and serum creatinine or cystatin C is non-linear, meaning that even slight elevations in these biomarkers can signal a substantial decrease in renal filtration capacity. Additionally, serum creatinine levels are affected by variables such as muscle mass, age, gender, dietary habits, and protein consumption, which can compromise its reliability as an early indicator of kidney damage.
Fig 1: Biomarkers play a crucial role in the early identification of kidney damage induced by drugs as well as in evaluating kidney function. Each biomarker corresponds to injury in a particular renal structure, and the causes of their release can vary for each marker used in detecting kidney impairment.
Cystatin C is a small protein produced by all nucleated cells, which is filtered through the glomerulus and is nearly entirely reabsorbed and broken down in the proximal tubules. Studies indicate that cystatin C may serve as a more dependable biomarker than creatinine or urea for the prompt identification of acute kidney injury, particularly drug-related nephrotoxicity.
Beyond conventional markers, a range of new urinary biomarkers has emerged for the early prediction and identification of nephrotoxic damage. These include urinary beta-2 microglobulin, total urinary protein, albumin, clusterin, kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL). Such biomarkers provide insights into tubular injury and inflammatory responses at earlier stages compared to traditional indicators.
New molecular biomarkers like microRNAs also hold potential for the early detection of nephrotoxicity. These small, naturally occurring RNA molecules regulate gene expression and maintain stability in biological fluids. Their straightforward detection via PCR methods and their stability at room temperature position them as promising non-invasive urinary biomarkers for identifying early renal injury.
Factors Increasing the Risk of Drug-Induced Nephrotoxicity
Certain groups of patients are more vulnerable to kidney damage from medications, making it crucial to identify at-risk individuals to prevent renal injury. Understanding patient characteristics, drug properties, and available diagnostic and treatment options is vital for reducing nephrotoxicity. Risk factors can be divided into three main categories: patient characteristics, baseline kidney function, and drug-related aspects.
Among patient characteristics, non-modifiable factors such as age and genetic susceptibility are significant. Older adults are particularly at risk for drug-induced nephrotoxicity due to physiological changes associated with aging and the presence of various comorbidities. As people age, their kidneys become more sensitive to medications, largely due to an imbalance in vasoconstrictor and vasodilatory responses that favors vasoconstriction. This altered vascular response, coupled with increased production of reactive oxygen species (ROS), makes the kidneys more vulnerable to damage.
At the cellular level, medications can impact the renal vascular pole, particularly affecting mesangial cells and the mesangial matrix in the glomerulus. Processes like mesangial cell proliferation, fibroblast activation, and excessive deposition of extracellular matrix can compromise the structural integrity of aging kidneys, increasing their susceptibility to drug-induced harm. Additionally, elderly patients often contend with comorbidities such as hypertension, heart failure, diabetes mellitus, and pre-existing renal or liver issues. Managing these conditions frequently involves medications like diuretics and ACE inhibitors, which primarily influence kidney function and may enhance nephrotoxicity through renal hypoperfusion and prerenal azotemia.
Genetic predispositions also play a crucial role in the likelihood of experiencing nephrotoxicity. Differences in drug-metabolizing enzymes, particularly within the cytochrome P450 (CYP450) system, can impact drug clearance and the formation of metabolites. Certain genetic polymorphisms may lead to decreased drug metabolism or the accumulation of harmful metabolites, thereby elevating the risk of kidney injury. These enzymes are expressed not only in the liver but also in the kidneys, contributing to the variability observed in drug-induced renal damage.
The distinct physiological traits of the kidneys amplify their susceptibility to nephrotoxic substances. The kidneys filter about 25% of the total blood flow, resulting in their exposure to significant levels of circulating medications. Moreover, renal tubular cells, particularly those in the loop of Henle, operate under relatively low oxygen conditions while still engaging in high metabolic activities facilitated by Na⁺/K⁺-ATPase pumps. This interplay of intense metabolic need alongside restricted oxygen availability increases the likelihood of cellular damage from toxic agents. The presence of transporters on both apical and basolateral membranes also affects drug accumulation, potentially raising the concentration of drugs within cells.
Several factors related to medications, including their dosage, treatment duration, solubility, molecular structure, and ionic charge, play a critical role in their capacity to induce nephrotoxicity. While the toxic effects are generally dependent on dosage and duration, some drugs have the potential to inflict irreparable kidney damage even with a single administration. Furthermore, nephrotoxicity is often more pronounced in individuals with pre-existing kidney issues. Poorly soluble drug metabolites, like those from ciprofloxacin and methotrexate, can crystallize in the renal tubules, resulting in crystal nephropathy. Conditions such as dehydration, low urine output, acidic urine pH, high dosages, and rapid medication administration intensify this risk. The formation of crystals can lead to tubular blockage and local inflammation, worsening kidney damage.
The prevalent use and easy access to nephrotoxic medications, including those available without a prescription, significantly contribute to both acute and chronic kidney ailments. In clinical settings, it is common for healthcare providers to overlook the concurrent use of various nephrotoxic drugs, especially when patients self-medicate with over-the-counter options. As a result, nephrotoxic events remain a significant contributor to renal insufficiency and its systemic complications.
In summary, individuals with pre-existing risk factors such as older age, genetic predisposition, and concurrent health issues like hypertension, diabetes, severe infections, and sepsis experience a higher incidence of nephrotoxicity. Medications can harm the kidneys either through their excretion pathways or by exerting direct pharmacological effects on renal tissues. Thus, it is crucial to identify which drugs are most closely linked to nephrotoxic effects and to clarify the mechanisms behind drug-induced kidney injury to enhance patient safety and clinical outcomes.
In conclusion, drug-induced nephrotoxicity poses a significant clinical issue, particularly for patients who undergo extended or repeated courses of nephrotoxic antibiotics post-cardiac surgery. The kidneys are particularly susceptible to toxic damage due to their unique physiological properties, significant blood flow, and active drug processing capabilities. Factors related to patients, including age, genetic factors, and existing health conditions, alongside drug characteristics such as dosage, treatment duration, and pharmacological properties, greatly affect the likelihood and severity of renal injury.
Nephrotoxic effects often develop gradually and may span several years, potentially resulting in chronic kidney disease or, in severe instances, end-stage renal failure necessitating dialysis or transplantation. Traditional biomarkers like serum creatinine, blood urea nitrogen, and estimated glomerular filtration rate are vital for evaluating kidney function; however, their limited sensitivity in detecting early-stage injuries highlights the necessity for enhanced diagnostic methods. New biomarkers such as cystatin C, NGAL, KIM-1, urinary proteins, and microRNAs present promising possibilities for the earlier identification of kidney damage before it becomes irreversible
Timely detection of patients at high risk, careful selection and appropriate dosing of nephrotoxic medications, along with consistent monitoring of both established and emerging renal biomarkers, are essential for preventing or mitigating drug-related kidney injury. It is also vital for healthcare providers to be informed about the additive and interactive effects of various nephrotoxic substances, including those available without a prescription. Incorporating early biomarker evaluations into standard clinical procedures could lead to better patient outcomes, lessen the long-term impact of chronic kidney disease, and improve the safety of drug treatments for at-risk populations.
REFERENCES
Fahmia Feroz, Sajad Qadir Bhat, Yamini Sharma, Incidence of Chronic Kidney Disease in Patients Receiving Nephrotoxic Antibiotics Post-Cardiac Surgery, Int. J. Med. Pharm. Sci., 2026, 2 (4), 48-57. https://doi.org/10.5281/zenodo.19773389
10.5281/zenodo.19773389
