Pharmacokinetics Of Oral Cyclosporin Research Articles

Early non-steady-state population pharmacokinetics of oral cyclosporine in renal transplant recipients.

This study aimed to evaluate the change in the pharmacokinetics (PK) of cyclosporine in the non-steady-state period in the first week after renal transplantation; the factors influencing this change, including genetic variability; and the time point concentration that correlated best with drug exposure. Data were obtained from 69 patients, and PK studies were conducted on postoperative days (PODs) 2, 3, and 7. Samples were taken pre-dose and at 1, 2, 3, 4, 6, 8, and 12 hours after drug administration. MDR1, CYP3A4, and CYP3A5 were genotyped. A population PK analysis and correlational analysis between the concentration at each time point and the area under the time–concentration curve were performed. A two-compartment model with first-order absorption was chosen. The rate and extent of drug absorption showed a significant increase on POD3, followed by a slight decrease on POD7. Until POD3, 8 hours post-dose was the single time point concentration that correlated best with drug exposure and 3 hours was the best time point on POD7. In both analyses, the MDR1 genotype showed potential as a factor influencing PK change. We conclude that oral administration of cyclosporine and dose adjustment based on a single concentration measurement might result in unexpected drug exposure during this early posttransplantation period.

Effect of Quercetin on The Pharmacokinetics of Oral Cyclosporine

Effect of Quercetin on The Pharmacokinetics of Oral Cyclosporine

Pharmacokinetics of oral cyclosporine (Neoral) in heart transplant recipients during the immediate period after surgery.

Neoral cyclosporine has better absorption characteristics than the original Sandimmun formulation. This has allowed Neoral to be administered orally in circumstances where Sandimmun had been ineffective, including the postoperative phase of liver transplantation. Sampling strategies, such as the measurement of drug concentration 2 h after oral administration, have been used in a variety of settings to estimate systemic exposure to Neoral (measured as the area under the blood concentration curve (AUC) of the drug) in blood. We conducted a pilot study to determine whether Neoral could be administered orally immediately after heart transplantation and to determine which pharmacokinetic parameters reflect systemic drug exposure in this setting. Eight male patients (mean age 50 years) undergoing a first heart transplant were studied. Neoral was administered orally before surgery and at 12-h intervals via a nasogastric tube after surgery. Twelve-hour pharmacokinetic profiles were obtained on postoperative days 1, 3 and 5. Cyclosporine concentrations were measured with the Dade Behring Emit assay, which is specific for the parent drug. Drug concentrations were dose-normalised and drug exposure was measured by the AUC. Drug exposure following administration (AUC(0-12)) was low on day 1 but increased by 99% between postoperative day 1 and day 5 ( P<0.05), indicating more complete absorption of cyclosporine; exposure in the first 4 h post-dose (AUC(0-4)) increased by 126% ( P<0.01), reflecting more rapid cyclosporine absorption, and the maximum blood concentration observed increased by 137% ( P<0.05) during the same period. The correlation between the cyclosporine trough concentration and AUC(0-12) was low on all days. Due to the changing pattern of cyclosporine absorption, concentration measurements at a single time point could not accurately predict 12-h exposure to the drug on all study days. However, the drug concentration at 2 h post-dose had a high correlation with drug exposure during the first 4 h (correlation of C(2) to AUC(0-4): r(2)>0.93 on all days). Absorption of Neoral was low immediately after heart transplantation but improved substantially during the first 5 days after surgery. No single timed measurement of drug concentration reflected cyclosporine exposure; however, the 2-h concentration did provide an accurate measure of the early phase of drug absorption (AUC(0-4)). Oral administration of Neoral may result in inadequate immunosuppression immediately after heart transplantation unless it is supplemented either by intravenous cyclosporine or by the use of an induction agent.

Pharmacokinetics of oral cyclosporine (Neoral) in heart transplant recipients during the immediate period after surgery

Abstract Neoral cyclosporine has better absorption characteristics than the original Sandimmun formulation. This has allowed Neoral to be administered orally in circumstances where Sandimmun had been ineffective, including the postoperative phase of liver transplantation. Sampling strategies, such as the measurement of drug concentration 2 h after oral administration, have been used in a variety of settings to estimate systemic exposure to Neoral (measured as the area under the blood concentration curve (AUC) of the drug) in blood. We conducted a pilot study to determine whether Neoral could be administered orally immediately after heart transplantation and to determine which pharmacokinetic parameters reflect systemic drug exposure in this setting. Eight male patients (mean age 50 years) undergoing a first heart transplant were studied. Neoral was administered orally before surgery and at 12-h intervals via a nasogastric tube after surgery. Twelve-hour pharmacokinetic profiles were obtained on postoperative days 1, 3 and 5. Cyclosporine concentrations were measured with the Dade Behring Emit assay, which is specific for the parent drug. Drug concentrations were dose-normalised and drug exposure was measured by the AUC. Drug exposure following administration (AUC0–12) was low on day 1 but increased by 99% between postoperative day 1 and day 5 (P<0.05), indicating more complete absorption of cyclosporine; exposure in the first 4 h post-dose (AUC0–4) increased by 126% (P<0.01), reflecting more rapid cyclosporine absorption, and the maximum blood concentration observed increased by 137% (P<0.05) during the same period. The correlation between the cyclosporine trough concentration and AUC0–12 was low on all days. Due to the changing pattern of cyclosporine absorption, concentration measurements at a single time point could not accurately predict 12-h exposure to the drug on all study days. However, the drug concentration at 2 h post-dose had a high correlation with drug exposure during the first 4 h (correlation of C2 to AUC0–4: r20.93 on all days). Absorption of Neoral was low immediately after heart transplantation but improved substantially during the first 5 days after surgery. No single timed measurement of drug concentration reflected cyclosporine exposure; however, the 2-h concentration did provide an accurate measure of the early phase of drug absorption (AUC0–4). Oral administration of Neoral may result in inadequate immunosuppression immediately after heart transplantation unless it

Pharmacokinetics of oral cyclosporin A when co-administered to enhance the oral absorption of paclitaxel.

The objective of this study was to evaluate the pharmacokinetics of oral cyclosporin A (CsA) when co-administered to enhance the oral absorption of paclitaxel. Patients received oral paclitaxel in doses of 60-360 mg/m(2) in combination with a dose of oral CsA of 15 mg/kg. Dose escalation of paclitaxel from 60 to 300 mg/m(2) resulted in a significant decrease in the area under the concentration-time curve (AUC) of CsA from 24.4+/-9.9 to 17.6+/-2.8 mg/l.h (p=0.03) (n=28). In conclusion, increases in the paclitaxel dose resulted in a decrease in the AUC of CsA. This observation may be explained by the increase in the co-solvent Cremophor EL of paclitaxel causing reduced absorption of CsA.

Pharmacokinetics of oral cyclosporin A when co-administered to enhance the absorption of orally administered docetaxel.

To evaluate the pharmacokinetics of oral cyclosporin A (CsA) when co-administered to enhance the absorption of orally administered docetaxel. Patients (n = 9) with histological proof of solid cancer received oral docetaxel 75 mg/m2 in combination with oral CsA 15 mg/kg. The area under the blood concentration-time curve (AUC) of CsA when combined with docetaxel 75 mg/m2 was 31.0+/-9.3 mg/l h (mean +/- SD). Compared with literature data of the same dose of CsA, AUC values in our study appear to be substantially higher. In addition, compared with the AUC values of CsA in combination with oral paclitaxel (previously published data), AUC values in this study are approximately 1.5-fold higher. The higher AUC values of CsA obtained in this study compared with literature data may be explained by competitive inhibition of cytochrome P450 (CYP) 3A4-mediated metabolism of CsA by docetaxel. In addition, the higher levels of CsA with docetaxel than with paclitaxel co-administration may be explained by the fact that docetaxel is almost exclusively metabolised by CYP 3A4, whereas paclitaxel is predominantly metabolised by CYP 2C8 and to a lesser extent by CYP 3A4.

The pharmacokinetics of oral cyclosporin a (neoral) during the first month after bone marrow transplantation

THE USE of cyclosporin A (CyA) has been complicated by its large interand intra-patient pharmacokinetic variability, which is likely due to variability in intestinal absorption. Patients with impaired intestinal integrity may have additional problems with absorption of CsA, further complicating selection of a therapeutic dose. The pharmacokinetic variability observed for CsA has prompted monitoring of CsA in blood to ensure appropriate concentrations are attained. Sandimmune Neoral, a new preparation of CsA, is absorbed independent of a bile secretion in the gut and has increased absorption and less variable pharmacokinetic parameters compared to the older preparation (Sandimmune) in solid organ transplants. CsA is used extensively in bone marrow transplantation (BMT) both in children and adults. This population has significant differences compared to solid transplant patients in intestinal integrity, possibly affecting intestinal absorption of CsA. These differences include a mucositis secondary to the preparative regimen used in BMT resulting in diffuse inflammation of the intestinal tract. In addition, these patients develop graft-versus-host disease (GVHD) and viral infections of the intestinal tract resulting in diffuse inflammation affecting possibly absorption of CsA. In the BMT population, Sandimmune Neoral may provide improved absorption and increased blood concentrations, as well as better control of CsA pharmacokinetic variability potentially improving therapeutic efficacy of oral CsA.

Pharmacokinetics of oral cyclosporin in children

Pharmacokinetics of oral cyclosporin in children

Effect of Terbinafine on the Pharmacokinetics of Cyclosporin in Humans

Cyclosporin is largely metabolized by hepatic cytochrome P450 enzymes, and azole drugs that inhibit cytochrome P450 may precipitate cyclosporin toxicity. The allylamine terbinafine binds to a small subfraction of hepatic cytochrome P450 in type I fashion, and has no effect upon hepatic metabolism of cyclosporin in vitro. The purpose of this study was to determine whether oral terbinafine alters the pharmacokinetics of oral cyclosporin in vivo. Twenty male volunteers (age 19-44 years), were randomly allocated to two groups. The first group received three single oral doses of cyclosporin 300 mg at intervals of 21 d. The second and third doses of cyclosporin were preceded by a 6-d course of oral terbinafine 250 mg each morning. A further 250 mg of terbinafine was taken with the second and third doses of cyclosporin. Blood levels of cyclosporin and terbinafine were monitored for 36 h after each dose. The second group received a 7-d course of terbinafine 250 mg each morning. On the seventh day a single dose of cyclosporin 300 mg was taken together with the terbinafine. Blood levels of both cyclosporin and terbinafine were monitored for 36 h. Two further single doses of cyclosporin 300 mg were given at intervals of 2 weeks and the cyclosporin levels again monitored. In both groups each cyclosporin dose was preceded by an 8-h fast. The mean peak blood concentration of cyclosporin when taken alone was 958 micrograms/l, and 822 when taken with terbinafine. The mean area under the curve for cyclosporin was 4207 micrograms/l/h when taken alone and 3665 when taken with terbinafine. The mean absorption half-life for cyclosporin when taken alone was 0.29 h, and 0.33 when taken with terbinafine. The mean time of maximum concentration and elimination half-life of cyclosporin were unaltered by terbinafine. The results suggest that terbinafine is likely to prove a safe systemic anti-fungal treatment for patients who are taking cyclosporin.

The Pharmacokinetics of Oral Cyclosporine A in Stable Kidney Transplanted Patients

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Pharmacokinetics of oral cyclosporin A in diabetic children and adolescents

Cyclosporin A (CsA) pharmacokinetics was studied in 19 diabetic children (mean age: 10.6 y). They were divided into prepubertal (I) and pubertal (II) groups according to plasma oestradiol or testosterone concentrations. The kinetic study was performed after a 72 h wash out period and a single oral dose of 7.5 mg/kg CsA. CsA in blood was measured by HPLC. The kinetic parameters: Cmax, tmax, t 1/2, AUC, CL/f, Vz/f and tss were calculated. No significant difference was found between the two groups. A significant negative correlation was found between Vz and both total cholesterol (r = -0.46), VLDL + LDL - cholesterol (r = -0.49) and VLDL + LDL - phospholipids (r = -0.58). CsA kinetics at steady-state were simulated by superimposition of single dose kinetics derived from each single dose. Measured steady-state blood concentrations were correlated (r = 0.80) with the values predicted by the simulation. The results suggest that CsA adjustment dosage of the CsA may be performed after a single oral dose using blood levels measured by HPLC. This procedure requires validation in further studies.

Pharmacokinetics of oral cyclosporin A (Sandimmun) in healthy subjects.

Extensive pharmacokinetic (PK) profiles after oral dosing of 300 mg cyclosporin A (CsA) were determined in whole blood by radioimmunoassay (RIA) in 14 healthy male volunteers, using two-compartment models with either first order (M1) or zero order (M0) absorption. According to zero order absorption the mean of the following PK parameters was determined: terminal half-life = 12.1 +/- 5.0 h, apparent volume of distribution at steady-state = 5.6 +/- 2.11 X kg-1, apparent clearance = 0.51 +/- 0.11 l X h-1 X kg-1. The time lag between drug ingestion and first blood level was short, 0.38 +/- 0.11 h. Drug absorption lasted for 2.8 +/- 1.6 h. The end of absorption was indicated in each individual by a sharp drop in blood levels. The observations support the assumption that CsA is absorbed in the upper part of the small intestine with a clear-cut termination (absorption window). This assumption may explain the high degree of variability in the bioavailability of CsA.

Evaluation of cyclosporin-phenytoin interaction with observations on cyclosporin metabolites.

We have observed that patients on concurrent cyclosporin and phenytoin therapy required increased doses of cyclosporin to maintain therapeutic concentrations of this novel immunosuppressive drug. We have, therefore, studied the influence of phenytoin on the pharmacokinetics of oral cyclosporin in six healthy male subjects. Cyclosporin concentrations in serum and whole blood were measured by high pressure liquid chromatography (h.p.l.c.) and radioimmunoassay (RIA). Concentrations of cyclosporin in whole blood were consistently higher than corresponding values in serum. Concentrations of cyclosporin determined by RIA were also consistently higher than those determined by h.p.l.c. Irrespective of the biological fluid (serum or whole blood) or the type of drug analysis (h.p.l.c. or RIA), changes in cyclosporin kinetics following phenytoin administration exhibited similar patterns. Phenytoin significantly reduced the maximum concentration and the area under the concentration-time curve and significantly increased total body clearance of cyclosporin. There was a statistically significant reduction of cyclosporin half-life (t 1/2) in whole blood using h.p.l.c. analysis. However, there was no significant change in cyclosporin t 1/2 in serum following phenytoin administration, using either form of drug analysis. Cyclosporin metabolites 17 and 18 were measured by h.p.l.c. in whole blood samples only, since these metabolites were found almost entirely in red blood cells. Phenytoin significantly reduced the Cmax and AUC of both metabolites, but no significant change was observed in the t 1/2 of either. Phenytoin enhanced the metabolism of antipyrine which was co-administered with cyclosporin to assess oxidative enzyme activity. We conclude that patients undergoing organ transplantation should be carefully monitored if they require phenytoin or other drugs known to accelerate oxidative metabolism.