Ciclosporin A Research Articles

Cytoprotective and Dose-Dependent Inhibitory Effects of Prostaglandin E<sub>1</sub> on Rat Pancreas Treated with Ciclosporin A

The prostaglandin E1 analogue rioprostil protects the pancreas from the noxious effect of ciclosporin A (CsA). To determine whether this cytoprotective action of rioprostil is dependent on or independent of inhibitory effects on pancreatic exocrine and endocrine secretion we studied the effect of different doses of rioprostil on pancreatic exocrine and endocrine secretions in the presence or absence of CsA. Rats received either CsA at a dose of 10 mg/kg body weight by tube feeding once in the morning, rioprostil at linearly increasing doses from 1.8 to 120 micrograms/kg body weight subcutaneously twice daily, a combination of both substances or NaCl. After 8 treatment days, the animals were operated on, and the pancreas isolated and arterially perfused. Insulin secretion was determined after stimulation with glucose, and amylase secretion after stimulation with CCK-8. Insulin and amylase secretion were significantly impaired by CsA. Rioprostil at doses of 1.8, 3.6 and 7.5 micrograms/kg body weight had no significant effect on insulin secretion in the absence of CsA but significantly improved insulin secretion in the presence of CsA. Higher doses of rioprostil significantly inhibited insulin secretion both in the presence or absence of CsA. Amylase secretion was not influenced by rioprostil at doses up to 15 micrograms/kg body weight but improved significantly amylase secretion in the presence of CsA. CsA blood and pancreatic tissue levels were not influenced by rioprostil at doses up to 120 micrograms/kb body weight. We conclude that the cytoprotective effect of the prostaglandin E1 analogue rioprostil against the noxious effect of CsA is dose dependent and is not related to its inhibitory action on endocrine and exocrine pancreatic secretion.

Functional and Morphological Changes of the Exocrine Pancreas in Ciclosporin-Treated Rats

We have examined whether or not ciclosporin A (CsA) affects structure and function of the exocrine pancreas. Male Wistar rats were treated once a day for 7 days with intraperitoneal injections of vehicle or 5, 15, 30, or 50 mg/kg of CsA. Following the CsA treatment, incorporations of [3H]thymidine into DNA and [3H]orotic acid into RNA were found to be significantly reduced in a dose-dependent manner up to 30 and 15 mg/kg, respectively, at which doses the incorporations reached a plateau. The incorporation of [3H]-L-leucine into protein also decreased by 36% at the dose of 5 and by 53% at the dose of 50 mg/kg of CsA. The activities of amylase and lipase in the pancreas also decreased in the CsA-treated rats. Furthermore, a significant reduction in the specific binding of [3H]N-methylscopolamine to muscarinic receptor was observed following the administration of CsA. The Scatchard analysis for the [3H]N-methylscopolamine binding to the pancreatic membrane revealed a significant decrease in Bmax, but not in Kd values in the CsA-treated animals. In addition, it was found histologically that administration of CsA induced cellular atrophy, cytoplasmic vacuolization, and cellular necrosis in the exocrine pancreas. These results strongly suggest that prolonged treatment with CsA may induce the suppression of pancreatic exocrine functions by decreasing the contents of amylase and lipase as well as the number of muscarinic receptors, possibly by the inhibition of the syntheses of protein and DNA in the exocrine pancreas.

Enteric solid dispersion of ciclosporin A (CiA) having potential to deliver CiA into lymphatics.

Solid dispersions composed of three components, ciclosporin A (CiA), surfactant (HCO-60) and a pharmaceutical additive, were prepared. As an additive, cellulose acetate phthalate (CAP), methacrylic acid and methacrylic acid methylester copolymer (Eudragit L-100) and hydroxypropylmethylcellulose phthalate (HP-55), which are generally used as enteric coating materials, were employed. The dissolution behavior of CiA from these enteric solid-dispersion system was studied according to the paddle method of JP XI in comparison with that of Sandimmun, an olive oily CiA solution as a reference. Solid dispersion of CiA preparation did not dissolve in the 1st test fluid (pH 1.2) in 2 h. In the 2nd fluid (pH 6.8), about 80% of CiA was dissolved within 12 min, though the dissolution rate was dependent on both the quality and quantity of the additives. An in vivo systemic and lymphatic availability study was performed with rats whose carotid artery and thoracic lymph duct were cannulated. After intrastomach administration of each CiA preparation to rats at a dose of 7 mg/kg, blood and lymph samples were collected for 6 h. One of the HP-55 preparations gave the highest plasma CiA level, Cmax = 0.99 +/- 0.20 (S.E., n = 4) micrograms/ml, and also showed the highest lymphatic availability, the percentage of dose delivered to the lymphatics in 6 h was 1.98 +/- 0.10% and the maximum lymph CiA level was 76.8 +/- 12.86 micrograms/ml. Lymphatic availability of CiA from Sandimmun was 0.78 +/- 0.11% and the peak plasma CiA level was 0.46 +/- 0.10 microgram/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of Histamine and Prostaglandin D<sub>2</sub> Release from Human Lung Mast Cells by Ciclosporin A

Cyclosporin A (CsA) is now widely used in the prevention/treatment of graft rejection and in the treatment of some human inflammatory diseases. We studied the effect of CsA on the release of chemical mediators from human lung mast cells in vitro. CsA (0.03-3 micrograms/ml) inhibited the release of histamine and prostaglandin D2 induced by anti-IgE from lung mast cells. CsA-induced inhibition of mediator release was not abolished by washing the cells before stimulation and it was not affected by the degree of purity of mast cell preparations. Our results indicate that CsA, in pharmacological concentrations, is a rapid and irreversible inhibitor of the release of preformed and de novo synthesized mediators from human lung mast cells. These findings might explain, at least in part, some of the therapeutic actions of CsA in vivo.

Effects of nitrendipine on blood pressure and blood ciclosporin A level in patients with posttransplant hypertension.

In order to evaluate the antihypertensive effectiveness and interaction with ciclosporin A (CS-A) nitrendipine, a dihydropyridine derivative calcium entry blocking agent, was used in 16 (13 men, 3 women) hypertensive renal posttransplant patients followed by the Nephrology Department of Hacettepe University Hospital. The patients did not receive any antihypertensive drug for a 7-day period. They were then given 20 mg/day nitrendipine for 3 weeks. At the end of this period, mean (+/- SE) supine blood pressure fell from 163/108 +/- 3.6/1.87 to 141/87 +/- 3.8/2.2 mm Hg (p less than 0.01), while the heart rate was unchanged. 14 of 16 patients achieved full control of blood pressure levels with 20 mg/day nitrendipine, and only 2 patients needed a higher dosage of 30 mg/day (20 + 10 mg). After 3 weeks of treatment no significant variations in blood chemistry or renal functional parameters were noticed. There was also no difference between blood CS-A levels before and after treatment with nitrendipine (218.06 +/- 33 vs. 222.68 +/- 26 ng/ml, p greater than 0.05). We conclude that short-term therapy with nitrendipine in renal post-transplant patients does not appear to be harmful and longer term studies are needed to fully evaluate safety and efficacy of this drug. Because it influences neither blood chemistry nor renal functional parameters and blood CS-A level, it may be preferable to other calcium channel blocking agents in this group of patients.

Nonimmunosuppressive ciclosporin H inhibits the growth and DNA synthesis of cultured normal human epidermal keratinocytes.

Ciclosporin H (CsH) is an epimer (11-D-N-methyl-L-valine) of ciclosporin A (CsA) devoid of immunosuppressive properties. The known antiproliferative effect of CsA on epidermal keratinocytes (EK) grown in vitro prompted us to study the effect of CsH (at the doses of 0.5, 1, 3.5 and 5 micrograms/ml) on the growth and DNA synthesis (5-bromo-2'-deoxyuridine incorporation). CsH was observed to reduce both the number and DNA synthesis of EK in a statistically significant manner at the dosage of 5 micrograms/ml after 24, 48 and 72 h in culture. These results show that the immunosuppressive properties of the ciclosporins (Cs) are dissociated from the antiproliferative ones on EK and highlight the interest of further in vivo studies that may lead to therapeutic applications of Cs in hyperproliferative epidermal diseases requiring no immunosuppression.

Correlation between low CSA plasma concentration and severity of acute GvHD in bone marrow transplantation.

Between 1982 and 1986 51 patients were treated with ciclosporin a (CSA) to prevent graft versus host disease (GvHD) after bone marrow transplantation (BMT). Major side effects of the drug were tremor, hypertension, hepatotoxicity and nephrotoxicity. Acute GvHD 0 degree to II degree occurred in 80% of our patients, and GvHD III degree and IV degree in 20% despite the use of CSA. Two to four days before the onset of GvHD, CSA serum levels were significantly lower on the average in patients who developed GvHD III degree and IV degree compared to the others. Our data indicate that plasma CSA concentrations higher than 250 ng/ml should be achieved to reduce the severity of GvHD after BMT.

Prophylactic and therapeutic effects of ciclosporin A in murine Schistosomiasis mansoni: studies on bisexual and unisexual infections and the hepatic inflammatory response.

Ciclosporin A (CsA), administered subcutaneously as 5 daily injections of 50 mg.kg-1, reduced the numbers of Schistosoma mansoni perfused from MF1 mice at 7 weeks post-infection. The timing of drug administration revealed that the antischistosomal effects were greater when CsA treatment coincided with or was within a few days of infection with the parasite. CsA exerted a clear prophylactic effect, which decreased with time and was virtually abolished by 4 months pre-infection. Adult worms treated in vivo were partially susceptible to CsA. In addition to its antiparasite action, CsA reduced hepatosplenomegaly due to schistosomiasis and diminished the granulomatous inflammatory response of mice to parasite eggs in the liver. The mode of action of CsA is not understood but evidence is presented that supports the proposition that the antiparasite effects are perhaps host-mediated.

Biological and pharmaceutical factors affecting the absorption and lymphatic delivery of ciclosporin A from gastrointestinal tract.

Absorption site and some biological and pharmaceutical factors affecting the absorption and transport of ciclosporin A (CiA) from the gastrointestinal (GI) tract into both the thoracic lymphatics and the systemic circulation have been studied in rats. In a group of rats whose gastric emptying of orally administered CiA in HCO-60 formulation, 7.0 mg/kg, was physically prevented, both the lymphatic and the systemic availabilities of CiA were negligibly low. CiA was orally administered to another group of rats whose major intestinal lymphatics as well as thoracic lymph ducts were cannulated, and it was revealed that the amount of CiA delivered to the major intestinal lymphatics was about six times greater than that of CiA transferred into the thoracic lymphatics. In bile fistulous rats, the systemic availability of CiA was predominantly decreased but the lymphatic availability was not so decreased. In contrast, solvents such as propylene glycol and polyethylene glycol affected both the systemic and the lymphatic availabilities of CiA, which were also dependent on the absorption site. In particular, the lower small intestine does not contribute to the lymphatic availability of CiA.

M-Mode Echocardiographie Findings after Successful Orthotopic Heart Transplantation

M-mode echocardiography (echo) was used to investigate 10 male recipients (mean age 34 ± 9 years) of an orthotopic heart transplant (T) 71 ± 21 days (mean ± SD) after surgery. None of the transplant patients presented with evidence of graft rejection (GR) as determined by clinical, cytoimmunological and histological parameters. All patients were on immunosuppressive therapy with ciclosporin A (CS-A). Nine normotensive males (mean age 47 ± 4 years) with normal hemodynamic and left ventricular (LV) angiographic findings and no evidence of coronary heart disease served as an echo control group (C). Mean arterial blood pressure and heart rate of group T were significantly higher as compared to group C. Echo parameters of group T indicated mild concentric LV thickening, whereas calculated LV mass was not significantly different in both groups (T 248.4 ± 59 vs. C 228.5 ± 35 g, NS). Contraction of LV septum as expressed by excursion and systolic thickening was significantly impaired, but posterior wall showed evidence of hypercontraction. Global LV function as expressed by circumferential fiber shortening (V(CF)) did not show any significant differences between groups (T 1.3 ± 0.2 vs. C 1.3 ± 0.2 circ./s, NS) nor did isovolumetric relaxation time. Two additional patients with acute GR under CS-A therapy were studied who demonstrated changes in LV dimensions, contractility and relaxation. In conclusion, successful detection of GR under CS-A therapy might be accomplished by echo. The above mentioned deviations from normal should be kept in mind during noninvasive postoperative follow-up of cardiac function. However, intraindividual changes may be more important in predicting rejection than absolute deviations from ‘normal values’.

Ciclosporin A: Correlation of Blood Levels with Acute Graft-versus-Host Disease after Bone Marrow Transplantation

Thirty patients undergoing allogeneic bone marrow transplantation (BMT) for hematologic malignancies received ciclosporin A (CS-A) as prophylaxis of graft-versus-host disease (GVHD). CS-A trough levels were determined in whole blood by radioimmunoassay (RIA); results were not used to adjust the CS-A dosage. Neither the dose of CS-A administered nor the CS-A concentration and fluctuation of blood levels during the first 15 days after BMT correlated with acute GVHD. Conversely in the 13 patients with acute GVHD, CS-A concentrations in the 10 days prior to the onset of the disease were increasingly lower with increasing severity of GVHD. Moreover, patients without GVHD had higher CS-A concentrations in a matched period of time. Upon withdrawal of CS-A treatment, 7 patients developed GVHD. There was no possibility to predict who would do so, but the analysis of CS-A disappearance profiles indicates that effective CS-A concentrations might be lower during long-term treatment than the concentrations required early after transplant. Despite these relationships, CS-A concentration is of little predictive value in the individual patient because of the considerable overlap among patients.

Clinical pharmacokinetics of ciclosporin A in bone marrow transplantation patients

Ciclosporin A (CsA) plasma concentrations were monitored by radioimmunoassay after administration IV and PO to 15 patients before allogeneic bone marrow transplantation. The clearance (10.4 +/- 5.41 1/h), half-life (26.4 +/- 14.6 h), and bioavailability (16% +/- 10%) calculated directly from experimental data showed wide interindividual variations. The kinetics after IV infusion, monitored over 2-5 days, appeared to be triphasic. A three-compartment open mamillary model was thus used to simulate the distribution and elimination kinetics of CsA. The distributive delay between administration PO and absorption in the plasma was approximated using a series of six additional compartments connected with a single transfer rate constant. Then, for each patient, the experimental data corresponding to both IV and PO administration were fitted using a single set of rate constants. Clearance and bioavailability calculated from model parameters correlated well with direct estimations obtained from the areas under the concentration time curves. Drug monitoring and linear modeling will be used in an attempt to achieve stable predetermined plasma concentrations of CsA in bone marrow transplantation patients receiving the drug either IV or PO.