CsA Vehicle Research Articles

Efficacy and safety of 0.1% ciclosporin A cationic emulsion in dry eye disease: a pooled analysis of two double-masked, randomised, vehicle-controlled phase III clinical studies

Background/aimTo assess the treatment effect of 0.1% ciclosporin A cationic emulsion (CsA CE) versus vehicle on signs/symptoms of dry eye disease (DED) in various subgroups (moderate-to-severe DED/severe DED/Sjögren’s syndrome (SS)/SS...

Clinical utility of cyclosporine (CsA) ophthalmic emulsion 0.05% for symptomatic relief in people with chronic dry eye: a review of the literature.

To review the literature on the efficacy of cyclosporine (CsA) ophthalmic emulsion 0.05% on symptomatic relief in chronic dry eye disease. There is consistent evidence of objective improvements in chronic dry eye disease (Schirmer score, corneal and interpalpebral dye staining, and tear breakup time) with CsA, but variable results with symptomatic improvement, possibly due to patient tolerance of CsA, similar comforting effect with artificial tears and CsA vehicle, and the inherent subjective nature of symptom monitoring and analysis. This review explores the literature on CsA with special attention to symptomatic relief.

A randomized study of the efficacy and safety of 0.1% cyclosporine A cationic emulsion in treatment of moderate to severe dry eye.

PurposeThe SICCANOVE study aimed to compare the efficacy and safety of 0.1% cyclosporine A cationic emulsion (CsA CE) versus vehicle in patients with moderate to severe dry eye disease (DED).MethodsIn this multicenter, double-masked, parallel-group, controlled study, patients were randomized (1:1) to receive CsA CE (Ikervis®) or vehicle for 6 months. The co-primary efficacy endpoints at month 6 were mean change from baseline in corneal fluorescein staining (CFS; modified Oxford scale) and in global ocular discomfort (visual analogue scale [VAS]).ResultsThe mean change in CFS from baseline to month 6 (CsA CE: n = 241; vehicle: n = 248) was significantly greater with CsA CE than with vehicle (-1.05 ± 0.98 and -0.82 ± 0.94, respectively; p = 0.009). Ocular discomfort improved similarly in both groups; however, the percentage of patients with ≥25% improvement in VAS was significantly higher with CsA CE (50.2%) than with vehicle (41.9%; p = 0.048). In a post hoc analysis of patients with severe ocular surface damage (CFS score 4) at baseline (CsA CE: n = 43; vehicle: n = 42), the percentage of patients with improvements of ≥2 grades in CFS score and ≥30% in Ocular Surface Disease Index score was significantly greater with CsA CE (p = 0.003). Treatment compliance and ocular tolerability were satisfactory and as expected for CsA use.ConclusionCyclosporine A CE was well-tolerated and effectively improved signs and symptoms in patients with moderate to severe DED over 6 months, especially in patients with severe disease, who are at risk of irreversible corneal damage.

Immunotoxicologic effects of cyclosporine on tumor progression in models of squamous cell carcinoma and B-cell lymphoma in C3H mice

Many immunosuppressive drugs are associated with an increased risk of neoplasia, principally non-melanoma skin cancers and B-cell lymphomas. However, only 6 of the 13 immunosuppressive drugs tested in 2 year bioassays increased the incidence of neoplasia. For example, the 2-year bioassays conducted with cyclosporine (CSA), an International Agency for Research on Cancer (IARC) Group 1 human carcinogen, were negative. The purpose of these investigations was to use transplanted tumor models in immunocompetent, syngeneic mice to gain insight into the failure of the 2-year bioassay to show an increased incidence of neoplasia with CSA. C3H HeN mice were used in a battery of assays with a transplanted squamous cell carcinoma (SCC VII cells) or a B-cell, lymphoma (38C13 cells) cells to study effects of CSA on local growth and metastases, experimental metastases, and progression of established metastases. Mice received CSA twice weekly by subcutaneous (SC) injection at doses of 0.5, 5, or 50 mg/kg; controls received the CSA vehicle. CSA had a modest inhibitory effect on SC tumors initiated by 38C13 cells and on intramuscular tumors initiated by SCC VII cells. CSA also decreased the number of lung colonies and decreased the size, growth fraction and vascularity of established lung metastases initiated by SCC VII cells. In contrast, CSA increased progressive growth of metastases to the sentinel lymph node from an intramuscular SCC VII tumor, but had no effect cellular traffic to the node. In conclusion, CSA at doses up to 50 mg/kg did not facilitate tumor progression and it partially inhibited tumor growth, suggesting that suppression of tumor progression may partially explain the failure of CSA to act as a carcinogen in 2 year bioassays.

Inhibition of mitochondrial permeability transition to prevent the post-cardiac arrest syndrome: a pre-clinical study

Resuscitated cardiac arrest (CA), leading to harmful cardiovascular dysfunction and multiple organ failure, includes a whole-body hypoxia-reoxygenation phenomenon. Opening of the mitochondrial permeability transition pore (mPTP) appears to be a pivotal event in ischaemia-reperfusion injury. We hypothesized that pharmacological inhibition of mPTP opening may prevent the post-CA syndrome. Anaesthetized New Zealand White rabbits underwent a 15 min primary asphyxial CA and 120 min of reperfusion following resuscitation. At reflow, animals received an intravenous bolus of either cyclosporine A (CsA, 5 mg/kg) or NIM 811 (2.5 mg/kg), two potent inhibitors of mPTP opening, or the CsA vehicle (control). Short-term survival, haemodynamics, regional (sonomicrometry), and global cardiac function (dP/dt and aortic flow) were assessed. We measured markers of cellular injuries and/or organ failure, including troponin Ic release, lacticodehydrogenase, lactate, creatinine, and alanine aminotransferase. Cyclosporine A and NIM 811 significantly improved short-term survival, post-resuscitation cardiac function, as well as liver and kidney failure (P < 0.05). CsA and NIM 811 both attenuated in vitro mPTP opening (calcium retention capacity by spectrofluorimetry) and restored oxidative phosphorylation when compared with controls (P < 0.05). These data suggest that pharmacological inhibition of mPTP opening, added to basic life support, attenuates the post-CA syndrome and improves short-term outcomes in the rabbit model.

Conversion of Immunosuppressive Monotherapy from Cyclosporin A to Tacrolimus Reverses Bone Loss in Rats

Tacrolimus is used for transplant patients with refractory graft rejection and those with intolerance to cyclosporin (CsA), without the disfiguring adverse effects frequently attributed to CsA therapy. Since we have shown that CsA-associated bone loss can also affect alveolar bone, the purpose of this study was to evaluate the effects of conversion of monotherapy from CsA to tacrolimus on alveolar bone loss in rats. Groups of rats were treated with either CsA (10 mg/kg/day, s.c.), tacrolimus (1 mg/kg/day, s.c.), or drug vehicle for 60 and 120 days, and an additional group received CsA for 60 days followed by conversion to tacrolimus for a further 60-day period. Bone-specific alkaline phosphatase (BALP), tartrate-resistent acid phosphatase (TRAP-5b), calcium (Ca(2+)), interleukin (IL)-1beta, IL-6, and tumor necrosis factor alpha (TNF-alpha) concentrations were evaluated in the serum. Analyses of bone volume, bone surface, number of osteblasts, and osteoclasts were performed. Treatment with CsA for either 60 or 120 days was associated with bone resorption, represented by lower bone volume and increased number of osteoclasts; serum BALP, TRAP-5b, IL-1beta, IL-6, and TNF-alpha were also higher in these animals. After conversion from CsA to tacrolimus, all the altered serum markers returned to control values in addition to a significant increase of bone volume and a lower number of osteoclasts. This study shows that conversion from CsA to tacrolimus therapy leads to a reversal of the CsA-induced bone loss, which can probably be mediated by downregulation of IL-1beta, IL-6, and TNF-alpha production.

Suppression of hepatic CYP3A1/2 and CYP2C11 by cyclosporine is not mediated by altering growth hormone levels.

Cyclosporine (CsA) suppresses drug metabolism by decreasing cytochrome P450 (P450) enzyme levels in rat liver. Growth hormone (GH) is known to pretranslationally regulate P450 expression. Thus, the suppression of P450 by CsA may involve GH as an intermediate. To address this question, we examined the effects of administering exogenous GH via twice daily subcutaneous injections and in conjunction with chronic subcutaneous CsA administration for 14 days on hepatic P450 expression. CsA alone decreased CYP3A1/2 and CYP2C11 significantly, in a manner similar to that previously found. When administered in the absence of CsA, GH also suppressed CYP3A1/2 and CYP2C11 protein levels as compared with GH vehicle. In the presence of CsA, GH did not cause further suppression of either CYP3A1/2 or CYP2C11 expression when compared with CsA treatment with GH vehicle. Testosterone in vitro catalytic assays confirmed that CsA and GH separately cause significant decreases in activity levels. Also, the concomitant administration of GH and CsA caused lowered production of 16alpha-, 2alpha-, 6beta-, and 2beta-hydroxytestosterone as compared with the administration of GH with CsA vehicle and as compared with the administration of GH vehicle with CsA. This study shows that GH is a dominating factor over CsA in determining hepatic P450 expression and activity. In addition, CsA does not seem to alter GH levels as a mediating event in suppressing P450 expression and activity. Since CsA given in combination with GH further suppressed P450 activity as compared with CsA given in combination with vehicle, this suggests that changes in hormonal status are likely to be one of the many factors that is responsible for the lack of a clear association between cyclosporine dosing and markers of toxicity.

Colchicine Suppresses Osteopontin Expression and Inflammatory Cell Infiltration in Chronic Cyclosporine Nephrotoxicity

Background: Colchicine (Col) is beneficial to renal injury because of its anti-inflammatory effect, but its mechanism has yet to be elucidated. The present study was designed to evaluate the inhibitory effects of colchicine on osteopontin (OPN) expression and the macrophage accumulation in chronic cyclosporine (CsA) nephrotoxicity in rats. Methods: Male adult Sprague-Dawley rats on a low salt diet (LSD, 0.05% sodium) were treated daily with Col (30 µg/kg), CsA (15 mg/kg), and both CsA and colchicine or vehicle (olive oil 1 ml/kg) for 4 weeks. The effects of colchicine on chronic CsA nephrotoxicity were evaluated by examining renal function, histopathology, and ED-1 positive cells. The expressions of OPN mRNA and protein were estimated respectively by Northern blot and immunohistochemistry. Results: Compared with vehicle-treated rats, CsA-treated rats showed an increase in serum creatinine, a decline in creatinine clearance rate, and tubulointerstitial fibrosis (all p < 0.01). Concomitant administration of colchicine reversed all of the above parameters (all p < 0.01). Of note, the upregulated expression of osteopontin mRNA and protein seen in CsA-treated rats was significantly decreased after colchicine treatment. Furthermore, the expression of osteopontin mRNA was strongly correlated with the number of ED-1 positive cells (r = 0.712, p < 0.001) and the tubulointerstitial fibrosis score (r = 0.586, p = 0.007). Conclusion: Colchicine is capable of abrogating the upregulation of chemotactic OPN expression and macrophage influx, and this is associated with improved renal tubulointerstitial fibrosis in chronic CsA nephrotoxicity.

Xenograft rejection of porcine islet-like cell clusters in normal, interferon-gamma, and interferon-gamma receptor deficient mice.

The aim of the present study was to evaluate the role of the T-cell cytokine interferon (IFN)-gamma in mediating macrophage activation in xenograft rejection. For this purpose, fetal porcine islet-like cell cluster (ICC) transplants were placed under the renal capsule of normal mice and mice with a homozygous targeted disruption of the IFN-gamma or the IFN-gamma receptor gene. Some of the mice were continuously infused with cyclosporine (CsA, 12.4 mg/kg body weight/day) or CsA vehicle by subcutaneously implanted osmotic pumps. Histological evaluation of the xenografts was performed 6 or 12 days after transplantation. All animals, irrespective of recipient group, readily rejected the ICC xenograft, although the rejection process was slightly delayed in mice deficient in IFN-gamma. Analysis of the infiltrating cells within the xenograft in knockout mice revealed a pattern similar to that found in control animals. Six days after transplantation, there was an abundant infiltration of macrophages (Mac-1, F4/80, and major histocompatibility complex II markers) in the ICC grafts. Quite in contrast, there was only a low to moderate number of T cells (CD3 marker) present in the ICC grafts. Treatment with CsA had no effect on the rejection process. In grafts removed from mice with a disruption of the IFN-gamma gene, occasional surviving endocrine cells, and in some cases also a few intact ICC, were found within the otherwise obliterated xenograft. Few or no surviving endocrine cells were found in the grafts obtained from the other groups of mice. Thus, the present study demonstrates that macrophage activation, and subsequent destruction of an ICC xenograft, can operate in the absence of IFN-gamma in the pig-to-mouse model.

Combined flurbiprofen and cyclosporin-A does not attenuate bone loss and exaggerates renal impairment

Cyclosporine (CsA) is a potent immunosuppressant that has revolutionized the success of organ transplantation. Flurbiprofen (FB), a propionic acid derivative NSAID, has been demonstrated in vivo to reduce osteoclast numbers in normal rats. The aim of this experiment was to determine whether addition of FB to CsA-treated rats could prevent the bone changes associated with CsA therapy. Forty-eight 10–12-week-old male Sprague-Dawley rats were randomized to receive, daily for 28 days: (1) CsA vehicle p.o. plus FB vehicle sc; (2) CsA (15 mg/kg) p.o. plus FB vehicle sc, (3) CsA vehicle p.o. plus FB (1.5 mg/kg) sc; and (4) CsA (15 mg/kg) p.o. plus FB (1.5 mg/kg) sc. Rats were weighed and venous blood sampled at baseline, 14 days, and 28 days for determination of glucose, Ca ++, BUN, creatinine, PTH, osteocalcin, and 1,25(OH) 2 vitamin D. Tibiae were removed following killing, after double labeling for histomorphometry. Body mass was significantly lower than control in all rats receiving CsA on days 14 and 28 while blood glucose was only elevated in the CsA alone group. Day 28 BUN and creatinine were significantly elevated in the CsA group and the combination of CsA and FB revealed an exacerbation of this trend. Vitamin D and osteocalcin were consistently increased in the CsA and CsA/FB groups. Bone histomorphometry showed evidence of trabecular osteopenia in CsA and CsA/FB groups. CsA alone resulted in elevated bone turnover. FB was unable to prevent the trabecular bone loss induced by CsA therapy. This experiment indicates no role for FB as a therapeutic option in CsA-induced bone disease at the given doses and duration of treatment by virtue of its lack of bone sparing ability and adverse renal effects when the two drugs are administered concurrently.

The direct effect of injectable cyclosporine and its vehicle, cremophor, on endothelial vascular cell adhesion molecule-1 expression. Ricinoleic acid inhibits coronary artery endothelial activation.

As in humans, rabbit coronary artery endothelium basally expresses vascular cell adhesion molecule-1 (VCAM-1). Treatment with parenteral cyclosporine (CsA) to prevent graft rejection in rabbits receiving heterotopic heart transplantation reduced VCAM-1 expression in coronary arteries not only in transplanted, but also in native rabbit hearts. To explore the mechanism of this effect, we co-incubated cultured human saphenous vein endothelial cells for 24 hr with CsA or its vehicle (containing polyoxyethylated castor oil, or Cremophor, and ethanol), at concentrations compatible with those achievable in plasma during administration of parenteral preparations of CsA. Cells were then stimulated with TNF alpha or IL-4 to induce VCAM-1 expression, assessed by a cell-surface enzyme immunoassay. Both CsA and vehicle inhibited IL-4-stimulated VCAM-1 expression in a dose-dependent manner (from [OD mU, mean +/- SEM] 230 +/- 5 to 165 +/- 3 for CsA 50 ng/ml, and to 181 +/- 6 for the corresponding vehicle concentration; P < 0.05 for both comparisons). To investigate whether this vehicle effect also occurs in vivo, we treated 9 New Zealand White rabbits with saline (n = 3), CsA (10 mg/kg/day, n = 3), or vehicle at corresponding doses (n = 3) for 6 weeks. Profiles of coronary arteries (> or = 48 for each group) were semiquantitatively scored (0-5) for VCAM-1 in immunostained heart cross-sections. Administration of both CsA and vehicle significantly reduced VCAM-1 expression compared with saline. Two vehicle components, ethanol and ricinoleic acid, were further evaluated directly on endothelial cells in vitro. While ethanol was ineffective, the monounsaturated fatty acid ricinoleic acid inhibited IL-4-stimulated VCAM-1 expression in a dose-dependent manner (IC50 between 10 and 100 microM). Thus, a fatty acid component of CsA vehicle exerts direct endothelial effects, potentially limiting arterial leukocyte recruitment during parenteral CsA treatment. This observation reveals a novel mechanism for CsA as an inhibitor of leukocyte-endothelial interactions, and furnishes a new potential rationale for the therapeutic action of unsaturated fatty acids in graft coronary disease.

Prostanoids and cyclosporin-mediated nephrotoxicity in rats: A critical appraisal

The involvement of arachidonic acid metabolism in cyclosporin (CsA) nephrotoxicity depending on CsA vehicle has been explored in this study. For this purpose creatinine clearance, urinary excretion and renal levels of eicosanoids were measured in the following rat experimental groups: group I, control; group II, CsA was administered in olive oil by gavage at 15 mg/kg/d for 7 d; group III, same as group II but 30 mg/kg/d; group IV, CsA was administered in fish oil by gavage at 15 mg/kg/d for 7 d; group V, same as group IV but 30 mg/kg/d; group VI, CsA was administered in olive oil at 15 mg/kg/d with prednisolone (1 mg/kg/d). The results indicate that (1) CsA nephrotoxicity and prostanoid alterations seem to be greatly improved when fish oil substitutes olive oil as a vehicle for CsA administration and (2) a correlation was found between eicosanoids measured and renal function, except in group II in which creatinine clearance remains unmodified but eicosanoids were altered, thus suggesting that other factors play a role in mediating nephrotoxicity due to cyclosporin.

Cyclosporine and cremaphor modulate von Willebrand factor release from cultured human endothelial cells.

Cyclosporine has been associated with microangiopathic hemolysis (MAHA) and other thrombotic complications of bone marrow and renal transplantation. MAHA is characterized by intravascular platelet aggregation, which, in some situations, is thought to be mediated by hyperactive high molecular weight von Willebrand factor (vWF). We have hypothesized that transplant-related MAHA may be caused by CsA-mediated release of von Willebrand factor from endothelial cells. This hypothesis was tested by studying vWF release from human umbilical vein endothelial cells primed with either CsA or cremophor EL. CsA and cremophor alone did not increase vWF release until toxic concentrations were reached (50-100 micrograms/ml). However, at therapeutic concentrations (0.1-5 micrograms/ml) vWF release by cells stimulated with thrombin, histamine, PMA, and the calcium ionophore A23187 was enhanced by both CsA and cremophor in a concentration-dependent manner. In single isolated endothelial cells, the thrombin-induced increase in cytosolic free calcium was enhanced by both CsA and cremophor. Preincubation for 24 hr with CsA but not cremophor suppressed vWF release after thrombin stimulation. These observations were mirrored by a concentration-dependent suppression of [3H]thymidine uptake by CsA. We conclude that CsA vehicle, cremophor, enhances stimulated vWF release in vitro, probably by processes dependent upon increased cytosolic free calcium. This suggests a possible mechanism for thrombotic transplant complications.

CHRONIC CYCLOSPORINE-INDUCED NEPHROPATHY IN THE RAT

Cyclosporine CsA nephrotoxicity was examined in male Sprague-Dawley rats with or without prior uninephrectomy, injected daily with 12.5 mg/kg CsA, and fed a salt-depleted or normal diet for 3-10 weeks. Control rats received the CsA vehicle. CsA induced a fall in creatinine clearance in salt-depleted rats, from 1.3 +/- 0.1 to 0.8 +/- 0.1 ml/min (P less than 0.001), and in normally fed rats from 1.8 +/- 0.2 to 1.0 +/- 0.2 ml/min (P less than 0.02). Vehicle treatment had no effect. The most striking morphologic changes were those of thick ascending limb cell atrophy with concomitant fibroblastic proliferation and collagen formation; these alterations were present in the inner stripe of the outer medulla and the medullary ray. The medullary-ray findings included S2-S3 degenerative changes as well and apparently correspond to the striped fibrosis described in human CsA nephropathy. The alterations were specific to the CsA group, progressive, and most severe in the salt-depleted, CsA-injected rats (on a scale of 0-4: 1.7 +/- 0.2 for medullary rays, and 2.0 +/- 0.2 for inner stripe, P less than 0.001). Morphologic changes predicted renal failure (r = 0.3, P less than 0.01 for cortical alterations, and r = 0.5, P less than 0.001 for medullary alterations). Prior uninephrectomy did not enhance these changes. Thus, chronic CsA administration impaired kidney function and induced morphologic alterations found in regions characterized by, and in nephron segments particularly vulnerable to, limited O2 availability. Salt depletion appears to accelerate the development of chronic CsA renal injury in the rat.

Effect of cyclosporin A on rat kidney catecholamines

The immunosuppressive agent, Cyclosporin A, (CsA) has been associated with nephrotoxicity and hypertension. The mechanism for these effects are not known. We therefore determined the levels of the catecholamines; epinephrine (EPI), norepinephrine (NE) and dopamine (DA) and some of their metabolites; epinine, dihyroxyphenyl-acetic acid (DOPAC), homovanillic acid (HVA), metanephrine (ME) and 3-methoxy-4-hydroxy-phenylglycol (MHPG) in the kidneys of rats treated intraperitoneally with either CsA (120μg/kg/body wt/day) or control vehicle (1ml olive oil/kg body wt/day). Six control or CsA treated rats were sacrificed at 1 hour or 24 hours after a single treatment or after 7 days of daily treatment. Renal catecholamine levels were determined using HPLC-amperometric detector. Treatment with CsA increased renal NE and EPI levels by 59% and 70% respectively within 1 hour. In the rats sacrificed 24 hours after treatment, renal NE, EPI and DA levels were similar to or less than the control levels. Treatment with CsA for 7 days resulted in marginal increases in renal NE (22%) and EPI (30%). These changes were associated with a significant decrease in the levels of catecholamine metabolites in the CsA treated kidneys as compared to the controls. The above findings suggest that increases in renal catecholamines may be involved in the CsA-induced hypertension and nephrotoxicity, perhaps by increasing renovascular resistance.

Effect of cyclosporine on steroidogenesis in rat Leydig cells.

Cyclosporine induces hypoandrogenism in adult male rats. In order to assess whether this effect of CsA may be due to a direct inhibitory effect on Leydig cell function, CsA (0, 50, 500, and 5000 ng/ml) was added to a collagenase-dispersed mixed Leydig cell preparation and incubated with and without hCG (0, 0.1, 0.3, 1.0, 3.0, and 10.0 ng/ml). Testosterone (T) production, mitochondrial cholesterol side chain cleavage (CSCC) and microsomal 17,20-desmolase enzyme activities in Leydig cells were determined after 3 hr of incubation. In the absence of CsA, stimulation of T production was maximal (about 16-fold) with 1.0 ng/ml hCG. With 50 and 500 ng/ml CsA there were no changes in either the hCG-stimulated T levels or the two enzymatic activities. However, 5000 ng/ml CsA significantly (P less than 0.05) reduced the hCG (1 ng/ml)-stimulated T levels, CSCC and 17,20-desmolase activities. The high dosage of CsA (5000 ng/ml) also caused a significant decrease in cell viability (P less than 0.05) during the incubation period. These effects of CsA were not due to cremophor EL, the CsA vehicle. This in vitro data indicate that high dosages of CsA (greater than or equal to 5000 ng/ml) appear to have a cytotoxic effect on rat Leydig cells that results in a decrease in T production. However, lower doses of CsA (less than 500 ng/ml) do not have any direct inhibitory effect on the rat Leydig cells, suggesting that the hypoandrogenic effect of in vivo CsA in rats is not due to any direct effect on the testis.

Influence of cyclosporin a on growth of an acute T‐cell leukaemia in PVG rats

Our objective was to examine the effect of cyclosporin A (CsA; 25 or 12.5 mg/kg) on growth of an acute (Roser) T-cell leukaemia in male PVG rats. The leukaemic blasts were shown (by immunocytochemical analysis) to have a mature, T-helper-cell phenotype, i.e., OX-19 (CD5) +/- , W3/25 (CD4)+, OX44+, MHC-class I+, OX-26+, corresponding to a population comprising 5% of normal rat medullary thymocytes. Animals received 20 X 10(3) viable tumour cells intramuscularly (day 0) and were given either CsA (25 or 12.5 mg/kg) or drug vehicle by gavage from day 0 or day 14, by which latter time leukaemic blasts normally appeared in the circulation. Administration of the higher dose of CsA from day 0 or day 14 significantly delayed the appearance of leukaemic cells in the peripheral circulation, whereas treatment with 12.5 mg/kg was without significant effect. CsA whole blood levels on day 17 were twice as high in leukaemic rats as in normal controls. Leukaemic infiltration of the spleen and the liver was reduced on day 17 after 25 mg/kg CsA, but no such effect was observed in lymph nodes or kidneys. A heterogeneous, host "reactive" cell population, which developed in response to the leukaemia, was inhibited by CsA, indicating that the effect of the drug was probably not mediated by host defence mechanisms. In CsA-treated leukaemic animals, there was biochemical evidence of synergistic impairment of glomerular and tubular function.

Long-term Cyclosporin Nephrotoxicity in the Rat: Effects on Renal Function and Morphology

This long-term study elucidates the development and reversibility of functional and morphological cyclosporin (CsA) nephropathy. Sprague-Dawley rats were given CsA (12.5 or 25 mg/kg per day) for 4, 8 or 16 weeks, or CsA during the first half of the 8- or 16-week period, and vehicle during the second half. Controls were given CsA vehicle throughout the study. Renal function was investigated with clearance methods (inulin, lithium, sodium and potassium). CsA-treated rats developed a focal renal interstitial fibrosis, the severity of which correlated to the accumulated CsA dose given (Kendall's tau = 0.56, P less than 0.0001). This renal lesion was not reversible. CsA reduced GFR and lithium clearance, and increased proximal fractional reabsorption. There was significant correlation (P less than 0.0001) between accumulated CsA dose and severity of functional impairment. Renal function improved following drug withdrawal, but in the compiled material, low-grade nephrotoxicity was evident 4 to 8 weeks after CsA withdrawal: GFR was decreased to 84% (P less than 0.02) of control levels. This indicates that CsA-induced renal focal interstitial fibrosis is progressive during treatment, and is not reversible, while functional CsA nephropathy is progressive but partly reversible if CsA is withdrawn.