Alternate-day therapy with methylprednisolone after renal transplantation

Azathioprine monotherapy in HLA-identical live donor kidney transplant recipients

The high success rate of HLA-identical sibling transplants and our previous experience with steroid-free immunosuppressive regimens and cyclosporine withdrawal prompted us to evaluate the safety and efficacy of monotherapy with azathioprine in 12 HLA-identical kidney transplant recipients with a serum creatinine concentration less than 176.8 mumol/L, a 1-way stimulatory index less than 2.0 in a post-transplant mixed lymphocyte culture, and a demonstrated tolerance of a minimum azathioprine dose of 1.0 mg/kg per day without leukopenia. Eleven of 12 patients were successfully converted to azathioprine monotherapy without a significant change in serum creatinine concentration for as long as 76 months. Benefits of steroid and cyclosporine withdrawal included a significant reduction in mean systolic and diastolic blood pressure, number of blood pressure medications, total serum cholesterol, and glycohemoglobin in diabetic subjects. Our results suggest that azathioprine monotherapy is safe and effective in a select group of HLA-identical sibling transplants, but these benefits must be carefully balanced against an associated risk of precipitating acute allograft rejection.

Comparative methylprednisolone pharmacokinetics in renal transplant patients receiving double- or triple-drug immunosuppression

OBJECTIVE

To assess the pharmacokinetics of chronic methylprednisolone therapy in renal transplant patients receiving double-drug (methylprednisolone and azathioprine) and triple-drug (methylprednisolone, azathioprine, and cyclosporine) immunosuppression.

DESIGN

Parallel, randomized trial.

PATIENTS

Fourteen renal transplant recipients (aged 29-65 y) evaluated in a public, university-affiliated hospital clinic.

INTERVENTIONS

All patients received their chronic oral dose of methylprednisolone via a 10-20-minute intravenous infusion.

MAIN OUTCOME MEASURES

Serum methylprednisolone concentrations were determined by HPLC and were used to generate pharmacokinetic parameters for this drug.

RESULTS

The mean daily methylprednisolone dosage was 19 +/- 19 mg in the double-drug group and 9 +/- 2 mg in the triple-drug group. Mean serum creatinine concentrations were 124 +/- 44 and 124 +/- 27 mumol/L, respectively. Mean methylprednisolone clearances were similar in both groups: 405 +/- 205 (double-drug) and 373 +/- 365 mL/h/kg (triple-drug) (p > 0.05). Mean steady-state volume of distribution was 1.5 +/- 0.8 L/kg in the double-drug group and 1.3 +/- 0.8 L/kg in the triple-drug group (p > 0.05). Plasma half-life ranged from 1.7 to 4.3 h (mean 2.7) in the double-drug group versus 1.4 to 3.4 h (mean 2.6) in the triple-drug group (p > 0.05).

CONCLUSIONS

These data indicate that cyclosporine had no definitive influence on methylprednisolone disposition. The results reveal a wide variation in methylprednisolone metabolism in renal transplant recipients receiving either a double- or triple-drug immunosuppressive regimen. Typically, methylprednisolone is prescribed according to a standardized dosing protocol that assumes minimal interpatient variation. Therefore, the pharmacokinetic variability noted in this study may have important clinical implications regarding the development of chronic toxicity (e.g., osteoporosis, hypothalamic-pituitary-adrenal suppression) and the attainment of successful immunosuppression.

Growth rate in children receiving alternate-day corticosteroid treatment after kidney transplantation

A controlled study of growth in children receiving alternate-day versus daily corticosteroid regimens was performed with 60 children and adolescents with kidney grafts. The study started 14 to 27 months after transplantation in patients with normal graft function, after a graft biopsy. Thirty-five patients were available for the growth study; 17 were randomly allocated to receive alternate-day therapy and 18 remained on a daily regimen. The cumulative dose was similar in the two groups, as were bone age and renal function. After 1 year of follow-up, the mean statural growth, expressed as change in SD score, was significantly better in those on the alternate-day regimen (+0.49 +/- 0.42 SD/yr) than in those on the daily regimen (-0.12 +/- 0.53 SD/yr; p less than 0.005). The difference was also significant when prepubertal and pubertal children were analyzed separately. During the second year of the study most children who were receiving daily treatment were given alternate-day therapy; their mean growth velocity increased to +0.29 +/- 0.35 SD/yr (p less than 0.05 vs the first year); children who had been on the alternate-day regimen since the outset of the study continued to have similar positive SD scores (0.52 +/- 0.37 SD/yr). Renal function remained stable throughout the study regardless of corticosteroid regimen, except in the case of one patient undergoing daily therapy who had a rejection crisis. We conclude that in children with a kidney graft a given cumulative dose of corticosteroid has a significantly lesser inhibitory effect on growth velocity when given on alternate days.

Hypertension and kidney transplantation

Patients with kidney transplants are often hypertensive. Investigators have described the characteristics of this hypertension in man. Moreover, the hypertension of kidney transplant patients has a higher probability of being responsive to surgical intervention than does hypertension in the general population. Yet the mechanisms of the many varieties of posttransplantation hypertension are not known in detail. Detailed studies that would best be done in animal models are rare. Both medical and surgical management of this transplantation-associated complication needs further study.

Comparison of daily and alternate-day prednisone during chronic maintenance therapy: a controlled crossover study

To determine if dose spacing of low dose chronic suppressive corticosteroid therapy would result in different effects on circulating T lymphocytes and hypothalamic-pituitary-adrenal (HPA) axis suppression, a crossover trial of two maintenance steroid regimens was performed. Twenty stable renal allograft recipients were treated for 6 mo with daily prednisone (DS) and then the same patients were abruptly converted to alternate-day prednisone (ADS) for another 6 mo. Total prednisone dosage was identical during the 6-mo study periods and only dose spacing differed. Both circulating T lymphocyte numbers and responsiveness to mitogens were less on the DS regimen. Patients gained weight on DS and lost weight on ADS. Five of the 20 patients developed infections on DS. However, HPA suppression was not different on the two regimens. These findings suggest that dose spacing alters the immunosuppressive and metabolic response to prednisone, even at low dose.

The management of dialysis and transplantation in children

Children with severe renal failure face numerous problems which are unique to their age group. The physiological and psychosocial changes which characterize growth and development must be integrated into the medical care of children requiring dialysis and renal transplantation. Congenital abnormalities are of greater importance in the young age group and glomerulonephritis less frequent as a cause of terminal renal failure. The problems of children during chronic hemodialysis often include retarded growth, sexual maturation and emotional development. Modifications in medications, equipment and technique are required for infants undergoing dialysis or transplantation. Growth following renal transplantation has been variably and related to renal function, age at transplantation, steroid therapy, and serum somatomedin activity. Rehabilitation has been achieved with both modes of therapy but is more likely following successful renal transplantation.

Growth in children with renal failure

Chronic renal insufficiency in childhood is often associated with growth delay. Undernutrition, osteodystrophy and diminished somatomedin levels appear to be importantly related to this growth delay. In many but not all children with renal failure and growth retardation, somatomedin levels are diminished, growth hormone levels are normal or elevated, and glucose tolerance is often abnormal. Following renal transplantation, growth restoration appears to be related to bone age, renal function, somatomedin and steroid therapy.

The aetiology of hypertension after renal transplantation in man

The renin-angiotensin-aldosterone system was studied in renal allograft patients, 70 per cent of whom were hypertensive.

Plasma-renin levels were found to be normal, and a normal increase was observed when patients were changed from the supine to the erect posture (P<0.01). However, aldosterone-secretion rates were found to be approximately four times normal, and a positive correlation between these values and diastolic blood-pressure was observed (r = 0-5, P = 0-05). In patients with intact kidneys a highly significant correlation between plasma-renin activity and aldosterone-secretion rate was observed (r = 0.8, P>0.05), but this normal correlation was not apparent in the patients with transplanted kidneys (r = 0.1, P>0.5). Thus the aldosterone-secretion rates in these patients was not under the control of the renin-angiotensin system.

Concurrent studies in adrenalectomized patients showed that they also had elevated aldosteronesecretion rates, and the injection of 14C-labelled cortisone acetate showed that they were capable of converting this steroid into aldosterone or an aldosterone-like metabolite. It is suggested that the hypertension seen after renal transplantation is related to the conversion of prednisone to a mineralocorticoid.

Further support for this hypothesis was obtained from studies in patients who had their therapy changed from daily prednisone to alternate-day methylprednisolone. They were found to secrete less aldosterone and all the patients became normotensive following this régime (P >0.1). In addition, patients treated with an aldosterone antagonist, spironolactone, showed a prompt decrease in blood-pressure.

It is concluded that the denervated transplanted kidney is able to maintain normal blood-pressure homeostasis in man, and that hypertension Seen after renal allografting is largely due to the therapy with immunosuppressive steroids.