cyclosporin-g and Kidney-Diseases

Cyclosporine G (OG 37-324) reportedly is an efficacious immunosuppressant with less nephrotoxicity than cyclosporine A. This is a prospective randomized double-blinded trial comparing cyclosporine G and cyclosporine A in cadaveric renal transplantation. Patient and graft survival, as well as major infectious complications, were not different between the two groups. Objective parameters of renal function, including serum creatinine, creatinine clearance, and inulin clearance, were routinely performed. These generally demonstrated less nephrotoxicity in those patients treated with cyclosporine G compared with cyclosporine A. Minor elevations of alanine aminotransferase were noted in the cyclosporine G-treated patients but this was not associated with acute morbidity. Overall, cyclosporine G appears to be equally as effective as cyclosporine A, but demonstrated notably less nephrotoxicity.

Topics: Adult; Aged; Cadaver; Cyclosporine; Double-Blind Method; Female; Graft Rejection; Humans; Immunosuppressive Agents; Kidney Diseases; Kidney Function Tests; Kidney Transplantation; Kidney Tubular Necrosis, Acute; Male; Middle Aged; Prospective Studies; Tissue Donors

OG 37-325 (nva-cyclosporine, cyclosporine G) is structurally similar to cyclosporine A (CsA). We hypothesized that OG 37-325 may, therefore, be metabolized by P450 3A, an enzyme recently shown to metabolize CsA. To test this hypothesis, we employed the erythromycin breath test (ERMBT) to measure P450 3A activity on multiple occasions in twenty OG 37-325-treated renal transplant recipients. When stable dosing was achieved, there was a measured 6-fold variation in the ratio of 12-hr whole-blood parent compound trough concentration (ng/ml, HPLC) to daily OG 37-325 dose (mg/kg) ([OG 37-325]/dose). In support of our hypothesis, there was an inverse correlation between the ERMBT result and the [OG 37-325]/dose ratio (r = -0.71, P < 0.001, n = 20); that is, patients with higher P450 3A activity generally required higher OG 37-325 doses to attain target blood levels. We also found that intrapatient variation in the [OG 37-325]/dose ratio observed over the course of the study correlated with changes in the ERMBT results (r = -0.67, P = 0.002). Inter- and intrapatient differences in [OG 37-325]/dose ratio were not predicted by patient age, serum cholesterol, blood hematocrit, or traditional liver chemistries. We conclude that P450 3A is generally rate limiting in the elimination of OG 37-325 in adult renal transplant recipients. Therefore, most drug interactions observed with CsA should also be expected with OG 37-325. We also conclude that intrapatient changes in OG 37-325 dosing requirements largely result from changes in P450 3A activity. The ERMBT may therefore provide useful information concerning patient compliance and may also serve as a useful guide to OG 37-325 dosing adjustments.

Topics: Adult; Breath Tests; Cyclosporine; Cyclosporins; Dose-Response Relationship, Drug; Erythromycin; Female; Humans; Immunosuppressive Agents; Kidney Diseases; Kidney Transplantation; Male; Middle Aged; Patient Compliance; Predictive Value of Tests; Regression Analysis

Cyclosporine A (CsA) nephrotoxicity has been suggested to be aggravated in the presence of ischemia, as occurs after renal transplantation. Cyclosporine G (CsG) may be less nephrotoxic than CsA. This study evaluated in the rat (1) the effect of CsA and CsG on blood flow and the function of the kidney subjected to 60 min of warm ischemia and (2) the protective effect of the calcium antagonist verapamil (VP). After left nephrectomy, ischemia was induced in the right kidney by the clamping of the kidney pedicle for 60 min, which resulted in a significant increase in serum creatinine (SCr) to 2.30 +/- 0.25 mg/dL by Day 1 with 25% mortality by Day 7. The administration of CsA or CsG (20 mg/kg i.v. daily for 7 days) after 60 min of renal ischemia significantly increased SCr and mortality compared with ischemia alone. In another set of experiments, 60 min of warm ischemia was applied to the right kidney and RBF was measured in both kidneys with a laser Doppler flowmeter. Blood flow in the ischemic kidney returned to the preischemic level by 15 min after the removal of the vascular clamp in the control animals. In contrast, in animals treated with CsA, a significant decrease in RBF was seen in both kidneys; however, blood flow in the ischemic kidney was significantly lower than that in the nonischemic kidney. CsG also decreased RBF in both kidneys, although in the left (nonischemic) kidney, RBF remained significantly higher with CsG than with CsA.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Creatinine; Cyclosporine; Cyclosporins; Ischemia; Kidney; Kidney Diseases; Male; Nephrectomy; Rats; Rats, Sprague-Dawley; Renal Circulation; Verapamil

Chronic tubulointerstitial nephropathy during long-term cyclosporine A (CsA) use has led to a search for equally effective but safer analogues. In this study we evaluated one of these analogues, cyclosporine G (CsG), in a rat model of chronic cyclosporine nephrotoxicity. CsG has immunosuppressive effects equivalent to CsA when dosed on a weight basis. Pair-fed Sprague-Dawley rats kept on a low-salt rice diet were given CsA 15 mg/kg, CsG 15 mg/kg, CsG 25 mg/kg, or vehicle subcutaneously. After 21 days, CsA animals had a lower glomerular filtration rate, measured by inulin clearance (0.16 +/- 0.04 ml/min/100 g) and higher serum creatinine (0.94 +/- 0.06 mg/dl) than CsG 15 mg/kg (GFR: 0.41 +/- 0.10 ml/min/100 g and serum creatinine: 0.68 +/- 0.09 mg/dl), CsG 25 mg/kg (GFR: 0.39 +/- 0.16 ml/min/100 g) or control rats (GFR: 0.62 +/- 0.06 ml/min/100 g; serum creatinine: 0.56 +/- 0.03 mg/dl), respectively (P < 0.05). The CsA group had considerable cortical and medullary injury (interstitial fibrosis and tubular atrophy), whereas both groups of CsG animals had more limited changes. Despite the same or larger doses of CsG on a weight basis, cyclosporine blood levels were significantly lower in CsG than CsA rats. We conclude that CsG, an analogue of cyclosporine with immunosuppressive activity equivalent to that of CsA, produced less nephrotoxicity in a model of chronic renal injury in rats, using both functional and structural parameters.

Topics: Animals; Cyclosporine; Cyclosporins; Immunosuppressive Agents; Kidney; Kidney Diseases; Male; Nephritis, Interstitial; Rats; Rats, Sprague-Dawley

Cyclosporine G (CsG) like cyclosporine A (CsA) is a cyclic endecapeptide where the alpha-amino butyric acid residue in position 2 is replaced by norvaline. We studied the effects of both drugs on renal function in a nontransplant rat model to avoid the additional variable of rejection. Age- and weight-matched pairs of male Sprague-Dawley rats were treated subcutaneously for 21 days with a daily dose of 25 mg/kg bw of either powdered CsA or CsG dissolved in 1 ml of olive oil. A control group (C) received olive oil only. Blood pressure (BP) and creatinine (Cr) were measured on days 0, 7, 14, and 21. On day 22, animals were weighed, anesthetized, and glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured using c14 inulin and 3H paraAminohippuric acid, respectively. Renal plasma flow and glomerular filtration rate were unaltered in CsG-treated animals compared to controls but significantly reduced in CsA-treated animals. Histologically, vacuolization and microcalcification were seen in significantly greater frequency among the CsA-treated animals. CsG with lesser nephrotoxic potential may prove to be of use in maintenance of therapy of transplants as well as selected autoimmune disorders.

Topics: Animals; Blood Pressure; Creatinine; Cyclosporine; Cyclosporins; Glomerular Filtration Rate; Kidney Cortex; Kidney Diseases; Male; Rats; Rats, Inbred Strains; Renal Circulation

We compared CsG and CsA in the DA-to-Lewis rat renal allograft model. At equivalent oral doses, plasma radioimmunoassay (RIA) CsG levels were higher than CsA (P less than 0.02). Neither drug prevented rejection at doses of 5 mg/kg/day. CsG-treated rats had a higher rejection rate at doses of 7.5 mg/kg/day (P less than 0.05). Both drugs were equally effective in preventing rejection at doses of 10 mg/kg/day. Neither drug was nephrotoxic at the doses used in this study. CsG is a potent immunosuppressant, and thus a potential clinical successor to CsA. Since CsG and CsA provide equivalent immunosuppression at therapeutic doses, CsG's clinical significance will ultimately depend on its nephrotoxicity in man.

Topics: Animals; Cyclosporine; Cyclosporins; Drug Evaluation, Preclinical; Graft Rejection; Kidney Diseases; Kidney Transplantation; Male; Rats; Rats, Inbred Lew; Transplantation, Homologous

The immunosuppressive potency, hepatotoxicity, and nephrotoxicity of Norvaline2-cyclosporine (Nva2-CsA), an analog of cyclosporine (CsA), were tested in a primate cardiac transplant model. After orthotopic cardiac transplantation in cynomolgus monkeys, immunosuppression was maintained with 16 mg/kg/day of either CsA or Nva2-CsA given intramuscularly in two divided daily doses. Immunosuppression was augmented with i.m. methyl-prednisolone, 1.0 mg/kg/day, which was tapered weekly by .1 mg/kg/day to a maintenance dose of .1 mg/kg/day. A group of 6 untransplanted monkeys were treated for a year with this dose of either CsA or Nva2-CsA and steroids. Renal biopsies were performed at one year. Among the transplanted monkeys, mean survival was 77.3 +/- 73 days for the CsA group and 16 +/- 8 days for the Nva2-CsA group. All 11 animals in the Nva2-CsA group died of cardiac rejection, but only 7 of 10 treated with CsA died of rejection. There was mild hepatic and renal dysfunction in both treatment groups, but no significant difference between groups as judged by blood urea nitrogen, creatinine, total bilirubin, serum glutamic oxaloacetic transaminate, and alkaline phosphatase. Cyclosporine levels were significantly higher in the CsA group. There were important morphological changes in both groups on histological examination of the kidneys, with proximal tubular vacuolation and enlargement of the juxtaglomerular apparatus predominating. It is concluded that Nva2-CsA is a less effective immunosuppressant than CsA when given parenterally in equal doses.

Topics: Animals; Chemical and Drug Induced Liver Injury; Cyclosporine; Cyclosporins; Heart Transplantation; Immunosuppression Therapy; Kidney Diseases; Macaca fascicularis; Myocardium; Time Factors