Diltiazem enhances gentamicin nephrotoxicity in rats

A systematic meta-analysis on the efficacy of pre-clinically tested nephroprotectants at preventing aminoglycoside nephrotoxicity

Nephrotoxicity limits the use of aminoglycoside antibiotics. Kidney damage is produced mainly in the renal tubule due to an inflammatory and oxidative process. At preclinical level, many drugs and natural products have been tested as prospective protectors of aminoglycoside nephrotoxicity. The main objective of this work was to make a systematic literature review of preclinical studies about aminoglycoside nephrotoxicity protection and a statistical analysis based on the meta-analysis methodology. Studies published up to January 2016 were identified. After applying inclusion criteria, 54 studies were chosen. The size of the experimental groups, means and standard deviations of data on renal function (i.e. plasma creatinine and blood urea nitrogen [BUN] concentrations) were extracted and registered in a database. The studies were grouped according to the mechanism of nephroprotection and their route of administration. The Mean Difference (95% confidence interval) was calculated for each study and group. 40 of 54 products tested produced an amelioration of aminoglycoside nephrotoxicity based on creatinine results. Also a dose dependent protective effect was observed (both in creatinine and BUN). Products orally administered were more effective than via i.p. Products with attributed antioxidant activity were the most used and those which proved statistically significant nephroprotection as a class effect. Aminoglycoside tubular reuptake inhibitors, excretion inducers and calcium channel blockers also showed a promising and rather homogeneous class tendency towards nephroprotection, although more research is necessary to obtain solid and conclusive results, based on a larger number of studies.

Protective effect of ebselen, a selenoorganic drug, against gentamicin-induced renal damage in rats

Gentamicin is an antibiotic that is widely used against serious and life-threatening gram-negative infections. However, its clinical use is limited by its nephrotoxicity. Oxidative stress and nitrosative stress are reported to play important role in gentamicin nephrotoxicity. In the present study we investigated whether ebselen, an inhibitor of oxidative stress and nitrosative stress prevents or reduces gentamicin-induced renal damage in the rat. For this purpose male Wistar rats were divided into five groups and treated as follows. Group 1 (control group): dimethyl sulphoxide, intraperitoneally, Group 2: Gentamicin 100 mg/kg b.wt. subcutaneously, Group 3: 5 mg/g b.wt. ebselen intraperitoneally, Group 4: 2.5 mg/kg b.wt. ebselen followed by 100 mg/kg b.wt. gentamicin subcutaneously one hour later, and Group 5: 5 mg/kg b.wt. of ebselen followed by 100 mg/kg b.wt. gentamicin one hour later for four consecutive days. Nephrotoxicity was evaluated histopathologically by light microscopy, and biochemically by the measurement of the plasma creatinine and urea levels. Parameters of oxidative stress such as reduced glutathione, malondialdehyde, and activities of superoxide dismutase and glutathione peroxidase were measured in the kidney. Serum nitrite and nitrate were measured as indicators of nitrosative stress. Treatment of rats with gentamicin resulted in statistically significant reduction in reduced glutathione levels (51%) and the activities of antioxidant enzymes superoxide dismutase (56%) and glutathione peroxidase (39%) as compared with the controls in the kidneys. Renal malondialdehyde level was increased significantly (43%) as compared with the controls. Plasma creatinine levels, urea levels and nitrite levels were significantly increased (4, 4.5 and 160% times respectively) as compared with the controls. Histologically, damage to the renal cortex and medulla was observed moderate to severe tubular necrosis and glomerular congestion. Pretreatment with 2.5 mg/kg b.wt. ebselen prevented gentamicin induced damage to medulla; however, renal cortex showed mild damage and biochemically indicators of oxidative stress and nitrosative stress were significantly reduced. Pretreatment with 5 mg/kg b.wt. ebselen prevented gentamicin-induced oxidative damage and nitrosative damage and renal damage almost completely in 78% of the rats, in the other 22% of the rats, ebselen pretreatment reduced gentamicin-induced renal damage. The results of the present study suggest that ebselen may be useful as a nephroprotective agent.

Renoprotective effect of Hemidesmus indicus, a herbal drug used in gentamicin-induced renal toxicity

BACKGROUND AND AIMS

Owing to the global trend towards improved 'quality of life', there is considerable evidence of an increase in demand for medicinal plants. The WHO guidelines define basic criteria for the standardization of herbal medicines. The present work is an effort in this direction to prove the safety and efficacy of Hemidesmus indicus Linn. in the management of nephrotoxicity induced by aminoglycosides such as gentamicin.

METHODS AND RESULTS

Simple, quality control methods using high performance thin layer chromatographic (HPTLC) phytochemical fingerprint, proximate analysis, and the stability of the H. indicus root powder were developed. From the toxicity study using albino Swiss mice, it was observed that the drug (H. indicus) was relatively safe up to 7 g/kg bodyweight dose. Efficacy was evaluated against gentamicin-induced nephrotoxicity in albino Wister rats. The study examined animals from the following groups: no treatment, gentamicin treated, gentamicin treated recovery, and gentamicin and plant treated. Animals from all groups were killed on day 13 of the study; those from gentamicin treated group were killed on the seventh day. Assessment of the drug efficacy drug was conducted by using haematological and histological examination.

CONCLUSION

The treatment with H. indicus helped in the management of renal impairment, which was induced by gentamicin in rats. This is evident from the results obtained for various kidney function tests for gentamicin, along with the results from the plant treated group, and is in comparison with the results found for the gentamicin recovery group. A histological examination of kidneys also supports the findings from haematological evaluations. The plant shows promise as an adjunct therapy along side aminoglycosides as it reduces nephrotoxicity caused by aminoglycosides.

Intravenous diltiazem and acute renal failure after cardiac operations

BACKGROUND

Perioperative administration of intravenous diltiazem to patients undergoing cardiac procedures has been shown to decrease the incidence of ischemia and arrhythmias. However, after adopting this practice in our cardiac surgery program, we perceived an increased incidence of postoperative renal dysfunction.

METHODS

A directed record review of postoperative renal function was conducted for consecutive patients undergoing cardiac operation for the time periods before and after adoption of prophylactic intravenous diltiazem (0.1 mg.kg-1.h-1 for 24 hours). The two groups were compared using chi 2 and two-sample t tests. The risk of development of postoperative renal failure was modeled with logistic regression.

RESULTS

Diltiazem-treated patients (n = 271) were similar to the control patients (n = 143) in terms of age (64 versus 61 years; p = 0.14), ejection fraction (0.46 versus 0.47; p = 0.61), baseline serum creatinine level (1.2 versus 1.1 mg/dL; p = 0.27), prevalence of comorbid conditions, and surgical characteristics. The prevalence of left main coronary artery disease was lower in the diltiazem group than the control group (39% versus 52%; p = 0.01). During the 7-day postoperative period, the average peak serum creatinine level was higher in the diltiazem group (1.7 +/- 0.9 mg/dL; mean +/- 1 standard deviation) than the control group (1.5 +/- 0.5 mg/dL; p = 0.003). The incidence of acute renal failure requiring dialysis was 4.4% in the diltiazem group versus 0.7% in the control group (p = 0.04). There was no difference in length of hospitalization or mortality. The risk of acute renal failure was strongly associated with intravenous diltiazem (adjusted odds ratio [AOR] 6.3; p = 0.08), age (AOR 2.5 per 10 years; p = 0.07), baseline serum creatinine (AOR 4.8 per 1 mg/dL; p = 0.02), the presence of left main coronary disease (AOR 5.3; p = 0.02), and the presence of cerebrovascular disease (AOR 4.5; p = 0.05).

CONCLUSIONS

Our retrospective analysis suggests that prophylactic use of intravenous diltiazem in patients undergoing cardiac operations was associated with increased renal dysfunction. Further studies of the risk and benefits of intravenous diltiazem in this setting should be undertaken.

Gentamicin nephrotoxicity in rats is not modified by verapamil

To assess whether calcium could be involved in the gentamicin-induced nephrotoxicity, we have studied the effect of the calcium channel blocker verapamil on renal function in rats intoxicated by gentamicin. Male Wistar rats were divided in three groups. In group I (n = 7) they were injected with gentamicin 100 mg/kg body wt/day s.c. for 5 days. In group II (n = 6), they received gentamicin and verapamil s.c. 2 mg/rat/day. In group III rats served as control. Plasma creatinine and creatinine clearance were daily measured. Rats treated with gentamicin showed a progressive increase in plasma creatinine and a drop in creatinine clearance. No differences between rats treated with gentamicin and those with gentamicin plus verapamil were observed. The urinary flow decreased after treatment with gentamicin, this decrease being more marked in rats treated with verapamil. No differences in daily urinary sodium and potassium excretion were found between intoxicated rats treated or not with verapamil. The present results show that, in rats, verapamil has no protective effect against the nephrotoxicity of gentamicin.

Effects of diltiazem on netilmicin-induced nephrotoxicity in rabbits

Aminoglycoside nephrotoxicity remains a common clinical problem and is the major cause of acute toxic renal failure in hospitalized patients. In recent studies, calcium channel blockers gave controversial results in the prevention of acute ischemic or toxic renal failure. The aims of the study were (i) to describe a rabbit model of mild renal failure (50% reduction in glomerular filtration rate with a mean value of 1.78 +/- 0.46 ml/kg/min) induced by netilmicin given intramuscularly at 20 mg/kg of body weight every 8 h for 5 days, (ii) to investigate the protective effect of diltiazem given at a therapeutic dose (1 mg/kg given intramuscularly every 8 h for 5 days), and (iii) to investigate the mechanisms of this protection through evaluation of function tests, optic histology, and glomerular morphometry. Animals treated with netilmicin and diltiazem exhibited an unchanged glomerular filtration rate compared with controls (3.39 +/- 0.58 versus 3.68 +/- 0.78 ml/kg/min, respectively). This protective effect was not associated with any change in systemic or renal hemodynamics (i.e., no change in renal plasma flow) or changes in the pharmacokinetics of netilmicin, as assessed by fractional excretion and cortical uptake. Netilmicin-induced tubular toxicity was unchanged by diltiazem. Our results suggest that (i) netilmicin exhibits a toxic effect at both the glomerular and the tubular levels, (ii) diltiazem, a calcium channel blocker, when given at low therapeutic doses, is able to prevent the aminoglycoside-induced renal failure through a potential glomerular mechanism. The precise mechanisms of the protection remain to be elucidated. These results deserve clinical evaluation in high-risk patients.

Comparative modulating effects of captopril, diltiazem, dietary calcium and pyridoxal-5'-phosphate on gentamicin-induced nephrotoxicity in the rat

1. Nephrotoxicity was induced in rats by injecting gentamicin intramuscularly (i.m.) at a dose of 80 mg/kg/day for 6 days. Treated animals demonstrated a typical pattern of aminoglycoside nephrotoxicity characterized histopathologically by necrosis of proximal tubular epithelium, and biochemically by increased serum creatinine and urea concentrations. Reduced glutathione (GSH) concentration in renal cortex was significantly decreased by gentamicin. 2. Simultaneous treatment of rats with gentamicin and either captopril or diltiazem significantly potentiated the gentamicin-induced increases in serum creatinine and urea and did not significantly affect the gentamicin-induced decrease in cortical GSH concentration. 3. Concomitant treatment with gentamicin and either Ca2+ or pyridoxal-5'-phosphate decreased serum urea level, did not significantly affect serum creatinine concentration, and significantly increased cortical GSH concentration in comparison to the values of these parameters following gentamicin treatment. 4. Histopathologically, the severity of gentamicin-induced renal damage was exacerbated by captopril, and even more so by diltiazem. Simultaneous treatment with gentamicin and either Ca2+ or pyridoxal-5'-phosphate produced only mild focal atrophy of renal tubular epithelium. Control rats had apparently normal histology. 5. In conclusion, captopril and diltiazem, at the doses used, significantly potentiated gentamicin-induced nephrotoxicity to a broadly similar extent. Although Ca2+ and pyridoxal-5'-phosphate, at the doses used, reduced significantly the severity of some of the manifestations of nephrotoxicity, they were equally ineffective in completely preventing the development of nephrotoxicity.

Effect of calcium antagonism by nifedipine and chlorpromazine on acute N-(3,5-dichlorophenyl)succinimide-induced nephrotoxicity in Fischer 344 rats

The nephrotoxicity induced by a wide variety of chemical compounds can be attenuated by agents which modify calcium ion (Ca2+) movement across membranes or calcium-dependent processes. The purpose of this study was to examine the ability of nifedipine, a calcium channel blocking drug, and chlorpromazine (CPZ), an antagonist of many calcium-dependent processes, to attenuate the nephrotoxicity induced by the agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) or its metabolite N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS). Male Fischer 344 rats (4 rats per group) were pretreated intraperitoneally (i.p.) with nifedipine (0.25 or 0.50 mg/kg), CPZ (1.0 or 5.0 mg/kg) or vehicle 1 h before NDPS (0.4 mmol/kg), NDHS (0.1 mmol/kg) or vehicle (sesame oil, 2.5 ml/kg). In separate experiments, rats were pretreated with nifedipine (0.25 or 0.50 mg/kg/day, i.p.) starting 2 days before NDPS or NDPS vehicle and continuing throughout the experiment. Renal function was monitored at 24 and 48 h. Nifedipine (single or multiple treatments) and CPZ (1.0 mg/kg) were ineffective in substantially altering NDPS (0.4 mmol/kg)-induced nephrotoxicity. However, CPZ (5.0 mg/kg) markedly attenuated all aspects of NDPS-induced nephropathy. Also, CPZ (5.0 mg/kg) partially protected against NDHS (0.1 mmol/kg)-induced renal effects. These results demonstrate the inability of the calcium channel blocker nifedipine to attenuate NDPS nephrotoxicity. Attenuation of NDPS nephrotoxicity by CPZ could suggest that CPZ is antagonizing calcium influx into renal tissue and/or renal intracellular calcium-dependent processes to modify the renal response to NDPS. However, the inability of CPZ to markedly attenuate NDHS nephrotoxicity could indicate that CPZ protected against NDPS nephrotoxicity by inhibiting biotransformation of the parent compound to its toxic chemical species.

Pathogenic factors in aminoglycoside-induced nephrotoxicity

Aminoglycoside antibiotics play an integral role in antimicrobial chemotherapy. Unfortunately, these drugs are known to cause nephrotoxicity in man and experimental animals. In fact, the incidence of renal dysfunction during the course of clinical treatment with aminoglycoside antibiotics is approximately 10%. Over the past two decades the elucidation of the pathogenesis of aminoglycoside-induced nephrotoxicity has been the subject of numerous investigations. This review describes the recent theories postulated to play a role in the pathogenesis of antibiotic-induced renal damage. In particular, the importance of amino-glycoside levels in the renal cortex or at the membrane binding site is examined in detail. The relevance of antibiotic tissue levels is reflected in the ability of other drugs to modify nephrotoxicity through an alteration in renal aminoglycoside content. The role of factors including age and diet in drug-induced nephrotoxicity is described. In clinical practice, aminoglycoside antibiotics may often be with other agents. The influence of aminoglycoside interaction with other drugs including vancomycin, cephalosporins and cytotoxic drugs is examined in the light of reports that nephrotoxicity is potentiated in these situations. In addition, this review focuses on the role of infection (pyelonephritis and septicemia) and bacterial endotoxin as pathogenic factors involved in aminoglycoside nephrotoxicity. Both the direct influence of endotoxin and the indirect effects of vasoactive mediators and inflammatory processes will be discussed. A multiplicity of factors is involved in the pathogenesis of aminoglycoside-induced nephrotoxicity and these are further amplified in the presence of infection.