Neoral (Cyclosporine) - Clinical Pharmacology

CLINICAL PHARMACOLOGY

Cyclosporine is a potent immunosuppressive agent that in animals prolongs survival of allogeneic transplants involving skin, kidney, liver, heart, pancreas, bone marrow, small intestine, and lung. Cyclosporine has been demonstrated to suppress some humoral immunity and to a greater extent, cell-mediated immune reactions such as allograft rejection, delayed hypersensitivity, experimental allergic encephalomyelitis, Freund’s adjuvant arthritis, and graft vs. host disease in many animal species for a variety of organs.

The effectiveness of cyclosporine results from specific and reversible inhibition of immunocompetent lymphocytes in the G₀- and G₁-phase of the cell cycle. T-lymphocytes are preferentially inhibited. The T-helper cell is the main target, although the T-suppressor cell may also be suppressed. Cyclosporine also inhibits lymphokine production and release including interleukin-2.

No effects on phagocytic function (changes in enzyme secretions, chemotactic migration of granulocytes, macrophage migration, carbon clearance in vivo) have been detected in animals. Cyclosporine does not cause bone marrow suppression in animal models or man.

Pharmacokinetics

The immunosuppressive activity of cyclosporine is primarily due to parent drug. Following oral administration, absorption of cyclosporine is incomplete. The extent of absorption of cyclosporine is dependent on the individual patient, the patient population, and the formulation. Elimination of cyclosporine is primarily biliary with only 6% of the dose (parent drug and metabolites) excreted in urine. The disposition of cyclosporine from blood is generally biphasic, with a terminal half-life of approximately 8.4 hours (range 5-18 hours). Following intravenous administration, the blood clearance of cyclosporine (assay: HPLC) is approximately 5-7 mL/min/kg in adult recipients of renal or liver allografts. Blood cyclosporine clearance appears to be slightly slower in cardiac transplant patients.

The Neoral^® Soft Gelatin Capsules (cyclosporine capsules, USP) MODIFIED and Neoral^® Oral Solution (cyclosporine oral solution, USP) MODIFIED are bioequivalent. Neoral^® Oral Solution diluted with orange juice or apple juice is bioequivalent to Neoral Oral Solution diluted with water. The effect of milk on the bioavailability of cyclosporine when administered as Neoral Oral Solution has not been evaluated.

The relationship between administered dose and exposure (area under the concentration versus time curve, AUC) is linear within the therapeutic dose range. The intersubject variability (total, %CV) of cyclosporine exposure (AUC) when Neoral^® or Sandimmune^® is administered ranges from approximately 20% to 50% in renal transplant patients. This intersubject variability contributes to the need for individualization of the dosing regimen for optimal therapy (see DOSAGE AND ADMINISTRATION). Intrasubject variability of AUC in renal transplant recipients (%CV) was 9%-21% for Neoral^® and 19%-26% for Sandimmune^®. In the same studies, intrasubject variability of trough concentrations (%CV) was 17%-30% for Neoral^® and 16%-38% for Sandimmune^®.

Absorption

Neoral^® has increased bioavailability compared to Sandimmune^®. The absolute bioavailability of cyclosporine administered as Sandimmune^® is dependent on the patient population, estimated to be less than 10% in liver transplant patients and as great as 89% in some renal transplant patients. The absolute bioavailability of cyclosporine administered as Neoral^® has not been determined in adults. In studies of renal transplant, rheumatoid arthritis and psoriasis patients, the mean cyclosporine AUC was approximately 20% to 50% greater and the peak blood cyclosporine concentration (C_max) was approximately 40% to 106% greater following administration of Neoral^® compared to following administration of Sandimmune^®. The dose normalized AUC in de novo  liver transplant patients administered Neoral^® 28 days after transplantation was 50% greater and C_max was 90% greater than in those patients administered Sandimmune^®. AUC and C_max are also increased (Neoral^® relative to Sandimmune^®) in heart transplant patients, but data are very limited. Although the AUC and C_max values are higher on Neoral^® relative to Sandimmune^®, the pre-dose trough concentrations (dose-normalized) are similar for the two formulations.

Following oral administration of Neoral^®, the time to peak blood cyclosporine concentrations (T_max) ranged from 1.5-2.0 hours. The administration of food with Neoral^® decreases the cyclosporine AUC and C_max. A high fat meal (669 kcal, 45 grams fat) consumed within one-half hour before Neoral^® administration decreased the AUC by 13% and C_max by 33%. The effects of a low fat meal (667 kcal, 15 grams fat) were similar.

The effect of T-tube diversion of bile on the absorption of cyclosporine from Neoral^® was investigated in eleven de novo  liver transplant patients. When the patients were administered Neoral^® with and without T-tube diversion of bile, very little difference in absorption was observed, as measured by the change in maximal cyclosporine blood concentrations from pre-dose values with the T-tube closed relative to when it was open: 6.9±41% (range -55% to 68%).

Pharmacokinetic Parameters (mean±SD)
	Dose/day 1	Dose/weight	AUC 2	C max	Trough 3	CL/F	CL/F
Patient Population	(mg/d)	(mg/kg/d)	(ng·hr/mL)	(ng/mL)	(ng/mL)	(mL/min)	(mL/min/kg)
De novo renal transplant4	597±174	7.95±2.81	8772±2089	1802±428	361±129	593±204	7.8±2.9
Week 4 (N=37)
Stable renal transplant4	344±122	4.10±1.58	6035±2194	1333±469	251±116	492±140	5.9±2.1
(N=55)
De novo liver transplant5	458±190	6.89±3.68	7187±2816	1555±740	268±101	577±309	8.6±5.7
Week 4 (N=18)
De novo rheumatoid arthritis6	182±55.6	2.37±0.36	2641±877	728±263	96.4±37.7	613±196	8.3±2.8
(N=23)
De novo psoriasis6	189±69.8	2.48±0.65	2324±1048	655±186	74.9±46.7	723±186	10.2±3.9
Week 4 (N=18)

¹Total daily dose was divided into two doses administered every 12 hours

²AUC was measured over one dosing interval

³Trough concentration was measured just prior to the morning Neoral^® dose, approximately 12 hours after the previous dose

⁴Assay: TDx specific monoclonal fluorescence polarization immunoassay

⁵Assay: Cyclo-trac specific monoclonal radioimmunoassay

⁶Assay: INCSTAR specific monoclonal radioimmunoassay

Distribution

Cyclosporine is distributed largely outside the blood volume. The steady state volume of distribution during intravenous dosing has been reported as 3-5 L/kg in solid organ transplant recipients. In blood, the distribution is concentration dependent. Approximately 33%-47% is in plasma, 4%-9% in lymphocytes, 5%-12% in granulocytes, and 41%-58% in erythrocytes. At high concentrations, the binding capacity of leukocytes and erythrocytes becomes saturated. In plasma, approximately 90% is bound to proteins, primarily lipoproteins. Cyclosporine is excreted in human milk. (See PRECAUTIONS, Nursing Mothers)

Metabolism

Cyclosporine is extensively metabolized by the cytochrome P-450 3A enzyme system in the liver, and to a lesser degree in the gastrointestinal tract, and the kidney. The metabolism of cyclosporine can be altered by the co-administration of a variety of agents . (See PRECAUTIONS, Drug Interactions)  At least 25 metabolites have been identified from human bile, feces, blood, and urine. The biological activity of the metabolites and their contributions to toxicity are considerably less than those of the parent compound. The major metabolites (M1, M9, and M4N) result from oxidation at the 1-beta, 9-gamma, and 4-N-demethylated positions, respectively. At steady state following the oral administration of Sandimmune^®, the mean AUCs for blood concentrations of M1, M9, and M4N are about 70%, 21%, and 7.5% of the AUC for blood cyclosporine concentrations, respectively. Based on blood concentration data from stable renal transplant patients (13 patients administered Neoral^® and Sandimmune^® in a crossover study), and bile concentration data from de novo liver transplant patients (4 administered Neoral^®, 3 administered Sandimmune^®), the percentage of dose present as M1, M9, and M4N metabolites is similar when either Neoral^® or Sandimmune^® is administered.

Excretion

Only 0.1% of a cyclosporine dose is excreted unchanged in the urine. Elimination is primarily biliary with only 6% of the dose (parent drug and metabolites) excreted in the urine. Neither dialysis nor renal failure alter cyclosporine clearance significantly.

Drug Interactions

(See PRECAUTIONS, Drug Interactions)  When diclofenac or methotrexate was co-administered with cyclosporine in rheumatoid arthritis patients, the AUC of diclofenac and methotrexate, each was significantly increased. (See PRECAUTIONS, Drug Interactions) No clinically significant pharmacokinetic interactions occurred between cyclosporine and aspirin, ketoprofen, piroxicam, or indomethacin.

Special Populations

Pediatric Population

Pharmacokinetic data from pediatric patients administered Neoral^® or Sandimmune^® are very limited. In 15 renal transplant patients aged 3-16 years, cyclosporine whole blood clearance after IV administration of Sandimmune^® was 10.6±3.7 mL/min/kg (assay: Cyclo-trac specific RIA). In a study of 7 renal transplant patients aged 2-16, the cyclosporine clearance ranged from 9.8-15.5 mL/min/kg. In 9 liver transplant patients aged 0.6-5.6 years, clearance was 9.3±5.4 mL/min/kg (assay: HPLC).

In the pediatric population, Neoral^® also demonstrates an increased bioavailability as compared to Sandimmune^®. In 7 liver de novo transplant patients aged 1.4-10 years, the absolute bioavailability of Neoral^® was 43% (range 30%-68%) and for Sandimmune^® in the same individuals absolute bioavailability was 28% (range 17%-42%).

Pediatric Pharmacokinetic Parameters (mean±SD)
	Dose/day	Dose/weight	AUC 1	Cmax	CL/F	CL/F
Patient Population	(mg/d)	(mg/kg/d)	(ng·hr/mL)	(ng/mL)	(mL/min)	(mL/min/kg)
Stable liver transplant2
Age 2-8, Dosed TID (N=9)	101±25	5.95±1.32	2163±801	629±219	285±94	16.6±4.3
Age 8-15, Dosed BID (N=8)	188±55	4.96±2.09	4272±1462	975±281	378±80	10.2±4.0
Stable liver transplant3
Age 3, Dosed BID (N=1)	120	8.33	5832	1050	171	11.9
Age 8-15, Dosed BID (N=5)	158±55	5.51±1.91	4452±2475	1013±635	328±121	11.0±1.9
Stable renal transplant3
Age 7-15, Dosed BID (N=5)	328±83	7.37±4.11	6922±1988	1827±487	418±143	8.7±2.9

     ¹AUC was measured over one dosing interval
²Assay: Cyclo-trac specific monoclonal radioimmunoassay
³Assay: TDx specific monoclonal fluorescence polarization immunoassay

Geriatric Population

Comparison of single dose data from both normal elderly volunteers (N=18, mean age 69 years) and elderly rheumatoid arthritis patients (N=16, mean age 68 years) to single dose data in young adult volunteers (N=16, mean age 26 years) showed no significant difference in the pharmacokinetic parameters.

CLINICAL TRIALS

Rheumatoid Arthritis

The effectiveness of Sandimmune^® and Neoral^® in the treatment of severe rheumatoid arthritis was evaluated in 5 clinical studies involving a total of 728 cyclosporine treated patients and 273 placebo treated patients.

A summary of the results is presented for the “responder” rates per treatment group, with a responder being defined as a patient having completed  the trial with a 20% improvement in the tender and the swollen joint count and a 20% improvement in 2 of 4 of investigator global, patient global, disability, and erythrocyte sedimentation rates (ESR) for the Studies 651 and 652 and 3 of 5 of investigator global, patient global, disability, visual analog pain, and ESR for Studies 2008, 654 and 302.

Study 651 enrolled 264 patients with active rheumatoid arthritis with at least 20 involved joints, who had failed at least one major RA drug, using a 3:3:2 randomization to one of the following three groups: (1) cyclosporine dosed at 2.5-5 mg/kg/day, (2) methotrexate at 7.5-15 mg/week, or (3) placebo. Treatment duration was 24 weeks. The mean cyclosporine dose at the last visit was 3.1 mg/kg/day. See Graph below.

Study 652 enrolled 250 patients with active RA with >6 active painful or tender joints who had failed at least one major RA drug. Patients were randomized using a 3:3:2 randomization to 1 of 3 treatment arms: (1) 1.5-5 mg/kg/day of cyclosporine, (2) 2.5-5 mg/kg/day of cyclosporine, and (3) placebo. Treatment duration was 16 weeks. The mean cyclosporine dose for group 2 at the last visit was 2.92 mg/kg/day. See Graph below.

Study 2008 enrolled 144 patients with active RA and >6 active joints who had unsuccessful treatment courses of aspirin and gold or Penicillamine. Patients were randomized to 1 of 2 treatment groups (1) cyclosporine 2.5-5 mg/kg/day with adjustments after the first month to achieve a target trough level and (2) placebo. Treatment duration was 24 weeks. The mean cyclosporine dose at the last visit was 3.63 mg/kg/day. See Graph below.

Study 654 enrolled 148 patients who remained with active joint counts of 6 or more despite treatment with maximally tolerated methotrexate doses for at least three months. Patients continued to take their current dose of methotrexate and were randomized to receive, in addition, one of the following medications: (1) cyclosporine 2.5 mg/kg/day with dose increases of 0.5 mg/kg/day at weeks 2 and 4 if there was no evidence of toxicity and further increases of 0.5 mg/kg/day at weeks 8 and 16 if a <30% decrease in active joint count occurred without any significant toxicity; dose decreases could be made at any time for toxicity or (2) placebo. Treatment duration was 24 weeks. The mean cyclosporine dose at the last visit was 2.8 mg/kg/day (range: 1.3-4.1). See Graph below.

Study 302 enrolled 299 patients with severe active RA, 99% of whom were unresponsive or intolerant to at least one prior major RA drug. Patients were randomized to 1 of 2 treatment groups (1) Neoral^® and (2) cyclosporine, both of which were started at 2.5 mg/kg/day and increased after 4 weeks for inefficacy in increments of 0.5 mg/kg/day to a maximum of 5 mg/kg/day and decreased at any time for toxicity. Treatment duration was 24 weeks. The mean cyclosporine dose at the last visit was 2.91 mg/kg/day (range: 0.72-5.17) for Neoral^® and 3.27 mg/kg/day (range: 0.73-5.68) for cyclosporine. See Graph below.