Cyclophosphamide-induced acute liver failure requiring transplantation in a patient with genetically deficient debrisoquine metabolism: a causal relationship?

Severe and prolonged cyclophosphamide-induced hepatotoxicity in a breast cancer patient carrying a CYP2B6*7 variant

As a widely used alkylating agent, cyclophosphamide often leads to various toxicities. Severe hepatotoxicity has been rarely reported in breast cancer patients receiving chemotherapy containing cyclophosphamide. Differences in cyclophosphamide metabolism may contribute to variability in adverse events of patients. Here, we report on a case of a 68-year-old Chinese female with breast cancer who experienced severe and prolonged hepatotoxicity induced by cyclophosphamide. Pharmacogenetic tests showed that she was a carrier of CYP2B6*7 allele and this is the first case of a CYP2B6*7 variant in the Han Chinese population so far reported. In addition, the patient was also a carrier of an ALDH3A1*2 variant potentially contributing to the occurrence of hepatotoxicity. CYP2B6 and ALDH3A1 genotyping may play a role in guiding cyclophosphamide therapy.

Role of venlafaxine in prevention of cyclophosphamide-induced lung toxicity and airway hyperactivity in rats

Cyclophosphamide (CP) is a drug used in chemotherapy and management of neoplastic diseases. This study aimed to investigate the prophylactic impacts of venlafaxine against CP-induced lung toxicity in rats. Rats were assigned randomly into 3 groups; control, CP (150 mg/kg) and CP/venlafaxine (50 mg/kg). On the end day, rats were sacrificed then bronchoalveolar fluid (BALF) and lungs were harvested. CP produced significant decrease in animal body weights and significant increase in lung/body weight ratio; levels of LDH, total protein, total and differential cell counts in BALF in comparison with control group. Moreover, significant elevation incontents of MDA, NOx, TNF-α and IL-1β and significant decline in GSH, SOD activities were observed in lung tissues. CP increased the response of tracheal zigzag to ACh. Histopathological results showed that CP increased inflammation and fibrosis in lung tissues. Venlafaxine restored most parameters to the normal levels. This protective effect of venlafaxine could be linked to its ability to reduce oxidative stress and inflammation.

Tranilast ameliorates cyclophosphamide-induced lung injury and nephrotoxicity

The world-wide increase in cancer incidence imposes a corresponding significant increase in the use of chemotherapeutic agents. Nephrotoxicity is a side effect frequently encountered with cyclophosphamide (CP), which is also well-known to cause acute and chronic lung toxicities. The current study focuses on the evaluation of the potential protective efficacy of tranilast against acute and subacute CP-induced lung and kidney injuries in male Swiss Albino mice. Intraperitoneal CP significantly impaired oxidant/anti-oxidant balance and increased inflammatory cell count in bronchoalveolar lavage fluid, serum creatinine, blood urea nitrogen (BUN), tumor necrosis factor-α (TNF-α) and lactate dehydrogenase (LDH) levels, with significant impairment of lung and kidney architectures. Tranilast taken orally for 8 and 14 days significantly enhanced mice anti-oxidant defense mechanisms; it increased lung and kidney SOD activity, GSH content and reduced lipid peroxidation. Tranilast significantly reduced serum creatinine and BUN. Furthermore, it decreased accumulation of inflammatory cells in the lungs. Serum TNF-α, LDH, total lung and kidney protein contents significantly declined as well. Histopathological examination revealed concomitant significant tissue recovery. Such results show a significant protective potential of tranilast against deleterious lung and kidney damage induced by CP, probably by enhancing host antioxidant defense mechanism, decreasing cytotoxicity, and decreasing expression of inflammatory cytokines.

Seleno L-methionine acts on cyclophosphamide-induced kidney toxicity

The anticancer drug cyclophosphamide (CP) has nephrotoxic effects besides its urotoxicity, which both in turn limit its clinical utility. The nephrotoxicity of CP is less common compared to its urotoxicity, and not much importance has been given for the study of mechanism of CP-induced nephrotoxicity so far. Overproduction of reactive oxygen species (ROS) during inflammation is one of the reasons of the kidney injury. Selenoproteins play crucial roles in regulating ROS and redox status in nearly all tissues; therefore, in this study, the nephrotoxicity of CP and the possible protective effects of seleno L-methionine (SLM) on rat kidneys were investigated. Forty-two Sprague-Dawley rats were equally divided into six groups of seven rats each. The control group received saline, and other rats were injected with CP (100 mg/kg), SLM (0.5 or 1 mg/kg), or CP + SLM intraperitoneally. Malondialdehyde (MDA) and glutathione (GSH) levels in kidney homogenates of rats were measured, and kidney tissues were examined under the microscope. CP-treated rats showed a depletion of renal GSH levels (28% of control), while CP + SLM-injected rats had GSH values close to the control group. MDA levels increased 36% of control following CP administration, which were significantly decreased after SLM treatment. Furthermore, these biochemical results were supported by microscopical observations. In conclusion, the present study not only points to the therapeutic potential of SLM in CP-induced kidney toxicity but also indicates a significant role for ROS and their relation to kidney dysfunction.

The effects of oral glutamine on cyclophosphamide-induced nephrotoxicity in rats

Nephrotoxicity is one of the adverse side effects of cyclophosphamide (CP) chemotherapy. In a recent study, we have demonstrated that oxidative stress and glutathione depletion play important roles in CP-induced renal damage. The aim of the study was to verify whether glutamine, the precursor for glutathione synthesis, prevents CP-induced oxidative stress and renal damage using a rat model. Adult male rats were administered a single dose of 150 mg/ kg body weight of CP intraperitoneally. The glutamine-pretreated rats were administered 1 gm/kg body weight of glutamine orally 2 h before the administration of CP. Vehicle/glutaminetreated rats served as controls. All the rats were killed 16 h after the dose of CP/vehicle. The kidneys were removed and used for light microscopic and biochemical studies. The markers of oxidative stress including malondialdehyde content, protein carbonyl content, protein thiol, reduced glutathione and myeloperoxidase activity, a marker of neutrophil infiltration, were measured in kidney homogenates. CP treatment-induced damage to kidney involved the glomeruli and the tubules. Pretreatment with glutamine reduced CP-induced glutathione depletion and increased myeloperoxidase activity. However, it did not prevent CP-induced lipid peroxidation, protein carbonylation and renal damage. The results of the present study suggest that glutamine pretreatment does not prevent CP-induced lipid peroxidation and renal damage, although it prevents CP-induced glutathione depletion and neutrophil infiltration significantly. It is suggested that mechanisms other than oxidative stress may also be involved and/or oxidative stress may be consequence and not the cause of CP induced renal damage.

Increased glutathione levels and activity of PON1 (phenyl acetate esterase) in the liver of rats after a single dose of cyclophosphamide: a defense mechanism?

The clinical utility of cyclophosphamide (CYP) as an anticancer drug is limited by its urotoxicity and nephrotoxicity and to a lesser extent by its hepatotoxicity. The present study was undertaken in order to find out the reason why liver is least susceptible of the three organs to CYP-induced damage although it is the major site for drug activation and metabolism. Adult female Wistar rats weighing 200-250 g were administered single intraperitoneal injection of CYP at the dose of 150 mg/kg body weight and sacrificed at various time intervals 6, 16 or 24h after the dose of CYP. The control rats were administered saline alone. Hepatotoxicity was assessed by measuring plasma alanine aminotransferase (ALT) activity and histopathology of the liver. Liver was used for the assay of reduced glutathione; activity of paraoxonase (PON1) malondialdehyde - marker of lipid peroxidation. Serum was used for the assay of ALT activity and PON1 activity. The level of reduced glutathione in the liver CYP treated rat was increased by 22% and 57% at 16 and 24h, respectively. Interestingly, a marked increase in the activity of PON1 (122%) was observed in the livers of CYP treated rats 24h after treatment. This was accompanied by significant increase in PON1 activity (23%) in the serum. No significant alteration in hepatic malondialdehyde level was observed at any time period after treatment. Serum ALT activity was increased slightly 24h after treatment with CYP. Mild liver damage was observed histologically only 24h after treatment with the drug. The present investigation shows for the first time that an increase in antioxidant levels in the liver may be a defense mechanism to prevent/minimize CYP-induced liver damage.

Dose adaptation of antineoplastic drugs in patients with liver disease

Dose adaptation for liver disease is important in patients treated with antineoplastic drugs because of the high prevalence of impaired liver function in this population and the dose-dependent, frequently serious adverse effects of these drugs. We classified the antineoplastic drugs marketed in Switzerland at the end of 2004 according to their bioavailability and/or hepatic extraction to predict their kinetic behaviour in patients with decreased liver function. This prediction was compared with kinetic studies carried out with these drugs in patients with liver disease. The studies were identified by a structured, computer-based literature search. Of the 69 drugs identified, 52 had a predominant extrarenal (in most cases hepatic) metabolism and/or excretion. For 49 drugs, hepatic extraction could be calculated and/or bioavailability data were available, allowing classification according to hepatic extraction. For 18 drugs, kinetic studies have been reported in patients with impaired liver function, with the findings generally resulting in quantitative recommendations for adaptation of the dosage. In particular, recommendations are precise for 16 drugs excreted by the bile (e.g. doxorubicin and derivatives and vinca alkaloids). Validation studies comparing such recommendations with kinetics and/or dynamics of antineoplastic drugs in patients with decreased liver function have not been published. We conclude that there are currently not enough data for safe use of cyctostatics in patients with liver disease. Pharmaceutical companies should be urged to provide kinetic data (especially hepatic extraction data) for the classification of such drugs and to conduct kinetic studies for drugs with primarily hepatic metabolism in patients with impaired liver function to allow quantitative advice to be given for dose adaptation.

In vivo prevention of cyclophosphamide-induced Ca2+ dependent damage of rat heart and liver mitochondria by cyclosporin A

The use of Cyclophosphamide, an anti-cancer and immunosuppressant drug, is accompanied by a number of side effects. Rats injected with a single dose of cyclophosphamide (200 mg kg-1 body weight) showed an increase in the levels of serum glutamate-oxaloacetate transaminase, serum glutamate-pyruvate transaminase, glucose-6-phosphate dehydrogenase and creatine phosphokinase isoenzyme by 53, 24, 55 and 135%, respectively. Also the ability of heart or liver mitochondria to retain accumulated Ca2+ and tetraphenylphosphonium ion was sharply affected in treated rats. Rats injected with the same dose of cyclophosphamide plus cyclosporin A (500 micrograms kg-1 body weight) showed reduction in the levels of those enzymes by about 44, 21, 43 and 57%, respectively compared to cyclophosphamide-treated rats. Cyclosporin A treatment also restored mitochondrial ability to retain accumulated Ca2+ and tetraphenyl phosphonium ions nearly to the level of untreated rats. We suggest that cyclophosphamide induced cardio and hepatotoxicity by increasing heart and liver inner mitochondrial membrane permeability to Ca2+. The protective effect of cyclosporin A against cyclophosphamide-induced damage also support this suggestion.