Pharmacokinetic study of cyclosporin A (Sandimmun ) in patients with primary biliary cirrhosis

Transcription

1 Br. J. clin. Pharmac. (1984), 18, Pharmacokinetic study of cyclosporin A (Sandimmun ) in patients with primary biliary cirrhosis S. ROBSON', J. NEUBERGER1, H. P. KELLER2, E. ABISCH2, W. NEIDERBERGER2, B. VON GRAFFENRIED3 & R. WILLIAMS1 'Liver Unit, King's College Hospital, London SE5 8RX, 2Biopharmaceutical Department and 3Clinical Research Department, Sandoz Ltd, Basle, Switzerland The pharmacokinetics of cyclosporin A (CS-A) were studied in 1 patients with primary biliary cirrhosis (PBC) after oral administration in steady state. Mean values for area under the blood concentration-time curve (AUC), time to maximal blood concentration (tmax), maximal blood concentration (Cmax) and elimination half-life (t½,z) were similar to results of previous studies in transplant patients. The variation between patients was large. No significant correlations of pharmacokinetic data with biochemical or histological parameters were found. Because of the high variability of pharmacokinetic parameters, patients with PBC treated with CS-A need to be regularly controlled for nephrotoxicity by estimation of serum creatinine and bioavailability (trough blood levels). Keywords cyclosporin A primary biliary cirrhosis pharmacokinetics Introduction Cyclosporin A (CS-A, Sandimmung) is the forerunner of a new generation of immunosuppressive agents which exert a specific action on the lymphoid cells and act by inhibiting the expression of helper cell function (Borel, 1982; Borel & von Graffenried, 1984). This drug is now widely used in the management of patients receiving bone marrow and solid organ grafts since it will suppress both the inductive phase of the immune response and also the effector phase in some, but not all, situations. CS-A has also been used with therapeutic benefit in both experimentally induced and human autoimmune disorders (Borel & von Graffenried, 1984; Nussenblatt et al., 1983a, b; Weetman et al., 1983). These disorders include primary biliary cirrhosis (PBC) (Routhier et al., 198), which is characterised by progressive damage to the intrahepatic bile ducts leading to cirrhosis and death. The pathogenesis of the disease is not yet established, although the many immunological abnormalities present in such patients suggest that defective suppressor T lymphocyte function may be implicated (Jones, 1983). In the preliminary study carried out by Routhier and colleagues (198) it was found that the drug exerted a beneficial effect on both the serological and histological features of the disease, but in the dose used (5-1 mg kg1 day-) there was a high incidence of side-effects, notably nephrotoxicity, and the trial was not continued. More recently, studies carried out in this Unit have shown that at a daily dose of CS- A of 4 mg/kg the functional suppressor cell defect can be corrected without the appearance of nephrotoxicity (Al-Aghbar et al., 1983). Since the drug is metabolised by the liver and excreted into the bile and subsequently undergoes enterohepatic circulation (Wood et al., 1983; Niederberger et al., 1983), abnormalities in these processes might be expected in patients with PBC. Intrahepatic shunting might influence bioavailability. In the present paper we report data on the pharmacokinetics of CS-A in patients with PBC at varying stages of the disease. 627

2 628 S. Robson et al. Methods Patients studied Ten patients attending the Liver Unit at King's College Hospital in London (UK) were studied. All had given their informed consent. Clinical, histological and biochemical data are given in Table 1. All patients had been on a constant dose of CS-A therapy (1.5-4 mg kg~1 day-) for at least 3 weeks before entering the study. On the day of study patient 1 received propranolol and patient 1 spironolactone, the remaining patients having no concurrent drug therapy. Analysis of drug records showed that during the month before study cholestyramine (patients 2, 4 and 5), pancreatic enzyme preparations (patient 4), iron (patient 7), folic acid (patient 7), vitamin K (patient 1), naproxen (patient 7), piroxicam (patient 9), paracetamol (patient 9), spironolactone (patient 1) and propranolol (patient 1) were used and in the last two patients the drugs were continued on the day of study. None of the patients have had a portocaval shunt...t Cs en I'll ll.. PI% e r.,l e4, ts -a -t Ito Ir 8 z 'I W) m oon oo b Ne N en v4- -N Nr-mo U,. Cu 11,._ CD 'Cu) CA Protocol *sc With an interval of 24 h since the last dose and after an overnight fast, each patient ingested a single oral dose of 5 mg/kg CS-A drink solution (1 mg CS-A per ml, dissolved in olive oil, Labrafil'9 and ethanol). The solution was 'injected' from a pipette directly into the mouth followed by 2 ml of cold milk. A normal breakfast was allowed 2 h later. Venous blood (5 ml) was sampled pre-dose and at 1, 2, 3, 4, 6, 8, 12 and 24 h after dosing into two separate heparinised tubes. The whole blood samples were deep-frozen within 3 min. Collection of samples was incomplete in patient 1 (samples at 8 and 24 h missing), patients 2, 3 and 4 (6 and 12 h), patient 5 (3, 6 and 12 h), patients 6, 8 and 1 (8 h), patient 7 (12 h) and patient 9 (sample taken at 1 h instead of 8 and 12 h). ".. 4- o "- CIO la C-. *.b la Q._ C5 c^ w a-, W)14 % rm oq -j ei oo o6 m vi 6 " "... i#>. -'4.... " a -o s siiro sit- I vc. eis " q -.Z a Du co Analysis of CS-A with h.p.l.c. The h.p l.c. method of Smith & Robinson (1984) wzs adapted as follows: to.5 ml whole blood,.1 ml methanol was added and vortexed for 5 s. Then 1.2 ml of internal standard solution (25 ng/ml of Cyclosporin D in acetonitrile/water 97.5/2.5 v/v) were added, the tubes vortexed again for 3 s and then centrifuged for 1 min at 1,4 rev/min. The clear supernatant. U c-'a e "t tnso O ue.3 Cu"

3 was decanted into a conical glass tube to which 1 ml N-hexane was added. After shaking for 1 min and centrifugation for 5 min, the upper N- hexane phase was pipetted off and.3 ml of water were added to the remaining layer. Traces of N-hexane were evaporated at 4 C for 2 s. Samples (5 Rd) were injected into a chromatographic system, which is described elsewhere (Nussbaumer et al., 1982). For this study, the first column 6 x 4.6 mm Spherisorb C-6/5,um (Phasesep, Queensferry, UK) was run with 3 ml/min acetonitrile/water (55/45 (v/v) at 72 C. The eluent between 2.5 and 6.5 min was cut and transferred on-line to a second column 15 x 4.6 mm Supelcosil C-18 (Supelco, Bellafonte, USA), which was run with 1.7 ml/ min acetonitrile/water 72/28 (v/v). Cyclosporin A and D were eluted after 9.5 and 11 min, respectively. In the meantime, the first column was washed with acetonitrile/water 72/28 (v/v). The total cycle time of the fully automated h.p.l.c system was 16 min. The limit of detection with UV at 21 nm was 25 ng/ml, the mean coefficient of variation was 8.1% (range %) for the within-assay precision, obtained from spiked blood samples over the whole concentration range (Nussbaumer et al., 1982). Analysis of CS-A with radioimmunoassay (RIA) Blood samples were analysed using assay procedure A (Donatsch et al., 1981). The assays were performed with cyclosporin RIA-kits. A blood sample of 2,ul was used per assay tube (CS-A RIA-kit, Sandoz Ltd, Basle, Switzerland. Instructions for use, 2nd ed., June 1983). Due to cross-reactivities with some metabolites the assay results represent the concentration of parent drug plus cross-reacting metabolites. Calculations The area under the blood level time curve (AUC) was calculated using the trapezoidal rule, the half-life of the terminal elimination phase t,½,,z was estimated from the last two blood level values. Correlations between various pharmacokinetic parameters (AUC, t½,,z, AUC RIA/h.p.l.c), histological staging ratio and biochemical data (bilirubin, alkaline phosphatase and AST) were performed using a linear model. Student's t-test was used to test the correlation coefficients for statistical significance. Results Short report 629 Calculations of AUC, Cma, Ctrough, tma, and t,/2,z are shown in Table 2 derived from measurements of CS-A assessed by both radioimmunoassay and h.p.l.c. The mean values of these parameters are similar to those obtained in transplant patients (Wood et al., 1983) with a very high variation. No significant correlations of pharmacokinetic data with biochemical or histological parameters were found. Discussion In patients with primary biliary cirrhosis (PBC) metabolism of drugs and other xenobiotics is usually impaired (Branch et al., 1973) and there are disturbances of biliary secretion (Raedsch et al., 1981). Cyclosporin A (CS-A), with a bioavailability after oral administration of 2 to 5% (Wood et al., 1983; Niederberger et al., 1983), is dependent on bile for its absorption, as shown by work in rats with bile fistulae where CS-A absorption is markedly reduced (Beveridge, 982). Thus it is surprising that a drug which is metabolised in the liver and excreted into the bile should apparently have pharmacokinetics in patients with PBC similar to those observed in patients without liver pathology. The cases selected for study were chosen to cover the entire spectrum of the disease, with two having an established cirrhosis and two having considerable cholestasis and disturbance of biliary excretion. It is of interest that in these four patients no greater abnormalities were found than in the other cases studied at an earlier stage of the disease. It would appear that in all those patients studied sufficient bile is excreted by the liver to result in adequate absorption of the drug. In addition, metabolism of the drug also seems to be unaffected in PBC since the ratio of AUC RLAJAUC h.p.l.c., an indicator of formed metabolites, is similar to what has been reported in patients with normal liver function (Follath et al., 1983) and shows no correlation with the stage of the disease, as none of the pharmacokinetic parameters investigated correlated well with any one feature of disease activity. Since at a dose of CS-A of about 4 mg kg-l day-1 the drug will correct the abnormal suppressor cell functional defect (Al Aghbar et al., 1983) with the absence of significant toxicity, this will be the dose range to be used in the prospective controlled trial which is now being carried out in this Unit in collaboration with

4 63 S. Robson et al. Table 2 Pharmacokinetic parameters derived from RIA and h.p.l.c. (LC) measurements 6f CS-A blood concentrations in patients with PBC Patient A UC (-24 h) AUC Cmax Ctrough tma2 tlhz (tq m;t' h) (nglml) (nglml) (h) (hj RIA LC RIAILC RIA LC RIA LC RIA LC RAI LC (2) (1) 1 (3) (4) (1)4 8 (1) 8 (1) (1) 3 (1) (3) _3 _3 Mean s.d at time 2 value for second (lower) maximum in brackets 3 blood drug concentration increased at 24 h 4 value below detection limit other international centres. Because of the wide scatter of pharmacokinetic results, dosage needs to be adjusted individually. Regular control of renal function is required to avoid overdosage and measurement of trough blood levels is recommended to detect those patients with low bioavailability. JN is a Wellcome senior clinical lecturer. References Al-Aghbar, M. N. A., Alexander, G. J. M., Neuberger, J., Nouri-Aria, K., Eddleston, A. L. W. F. & Williams, R. (1983). Effects of cyclosporin A on suppressor cell function in vivo and in vitro in primary biliary cirrhosis. Gut, 24, A97. Beveridge, T. (1983). Pharmacokinetics and metabolism of cyclosporin A. In Cyclosporin A, ed. White, D. J. G., pp Amsterdam: Elsevier Biomedical Press. Borel, J. F. (1982). Immunological properties of cyclosporin A. Heart Transplantation, 1, Borel, J. F. & Von Graffenried, B. (1984). Sandimunn (Cyclosporin A) and autoimmunity. In Proceedings of the Workshop on Recent Avances in Systemic Lupus Erythematosus, Geneva, Switzerland. London: Academic Press, (in press). Branch, R. A., Herbert, C. M. & Read, A. E. (1973). Determinants of serum antipyrine half-life in patients with liver disease. Gut, 14, Donatsch, P., Abisch, E., Homberger, E., Traber, R., Trapp, M. & Voges, R. (1981). A radioimmunoassay to measure cyclosporin A in plasma and serum samples. J. Immunoassay, 2, Follath, S., Wenk, M., Vozeh, S., Thiel, G., Brunner, F., Loertscher, R., Lemaire, M., Nussbaumer, K., Niederberger, W. & Wood, A. (1983). Intravenous cyclosporine kinetics in renal failure. Clin. Pharmac. Ther., 34, Jones, E. A. (1983). Primary biliary cirrhosis. In Advances in Hepatology, eds Thomas, H. C. & MacSween, R. N. M., pp Edinburgh: Churchill Livingstone. Niederberger, W., Lemaire, M., Maurer, G., Nussbaumer, K. & Wagner,. (1983). Distribution and binding of cyclosporin in blood and tissues. Transpl. Proc., 15, No. 4, Suppl. 1, Nussbaumer, K., Niederberger, W. & Keller, H. P. (1982). Determination of cyclosporin A in blood and plasma by column switching HPLC after rapid sample preparation. J. High Resolut. Chromatogr. Comm., 5, Nussenblatt, R. B., Palestine, A. G., Chi-Chao, Chan & Higgins, K. E. (1983a). Cyclosporine therapy in the treatment of intraocular inflammatory disease resistant to systemic corticosteroids or cytotoxic agents. Am. J. Ophth., 96, Nussenblatt, R. B., Palestine, A. G., Rook, A. H., Scher, I., Wacker, W. B. & Gery, I. (1983b). Treatment of intraocular inflammatory disease with cyclosporin A. Lancet, H, Raedsch, R., Lauterburg, B. H. & Hofmann, A. F. (1981). Altered bile acid metabolism in primary biliary cirrhosis. Dig. Dis. Sci., 26, Routhier, G., Epstein, O., Janossy, G., Thomas, H. C. & Sherlock, S. (198). Effects of cyclo-

5 sporin A on suppressor and inducer T lymphocytes in primary biliary cirrhosis. Lancet, H, Smith, H. T. & Robinson, W. T. (1984). Serum automated liquid chromatographic method for the determination of cyclosporin in plasma and blood using column switching. J. Chromatogr. Biomet. Applications (in press). Weetman, A. P., Ludgate, M., Mills, P. V., McGregor, A. M., Beck, L., Lazarus, J. H. & Short report 631 Hall, R. (1983). Cyclosporin improves Graves' ophthalmopathy. Lancet, ii, Wood, A. J., Maurer, G., Niederberger, W. & Beveridge, T. (1983). Cyclosporine pharmacokinetics, metabolism and drug interactions. Transpl. Proc., 15, Suppl. 1, (Received February 14, 1984, accepted June 2, 1984)