Mycophenolate mofetil vs azathioprine in a large population of elderly renal transplant patients.

BACKGROUND: Mycophenolate mofetil (MMF) has been shown to decrease acute rejection episodes after kidney transplantation, and has been associated with better graft and patient survival vs azathioprine (AZA). Previous studies reported a higher risk of death due to infection in elderly recipients treated with MMF-based immunosuppression. METHODS: We analysed 5069 elderly ( > 65 years of age) primary renal allograft recipients treated with either MMF or AZA reported to the Scientific Registry of Transplant Recipients between 1988 and 2000, and compared rates of acute rejection, late acute rejection, graft survival, death-censored graft survival, patient survival and death with a functioning graft. RESULTS: In Cox proportional hazard models, MMF was associated with lower rates of late acute rejection with 12 (RR = 0.72, P = 0.11) and 24 months (RR = 0.50, P = 0.028) of continuous therapy. In univariate analysis (Kaplan-Meier), MMF was associated with improved patient (P = 0.0003) and graft (P<0.0001) survival vs AZA, and trends toward improved patient and graft survival in multivariate analyses. CONCLUSIONS: These findings demonstrate the efficacy of MMF-based immunosuppression in elderly transplant recipients and do not suggest an increased risk of death compared to treatment with AZA.     

Mycophenolate mofetil pharmacokinetics in renal transplant recipients on peritoneal dialysis

We prospectively studied the impact of peritoneal dialysis (PD) on the pharmacokinetics of mycophenolic acid (MPA) in five patients following renal transplantation. Three patients had a glomerular filtration rate (GFR) of less than 10 ml/min and two had a GFR of more than 40 ml/min. Pharmacokinetics of MPA and of its main metabolite, mycophenolic acid glucuronide (MPAG), were studied during two consecutive 12-h periods (with and without PD). After initiation of PD in patients with severe renal impairment (GFR < 10 ml/min), MPA-area-under-the-concentration-curve (AUC) decreased up to 59 % and MPAG-AUC decreased up to 26 %. We did not observe any substantial changes in the MPA-AUC or MPAG-AUC of either patient with a GFR above 40 ml/min. Patients with a reduced GFR had much higher MPAG values than patients with a GFR above 40 ml/l; yet, we did not observe any differences in the MPA values. We found a significant inverse correlation between GFR and MPA-AUC (r = 0.81, P < 0.05) and between GFR and MPAG-AUC (r = 0.94, P < 0.01). While MPA was found only in traces in the peritoneal ultrafiltrate, the cumulative amount of MPAG removed by PD reached up to 2 g/12 h, representing 1.2 g of MPA. This is the first report describing a reduction in MPA-AUC and MPAG-AUC during PD. Further studies are needed to completely understand the pharmacokinetics of mycophenolate mofetil during PD. Received: 20 June 1997 Accepted: 26 August 1997     

Differential influence of azathioprine and mycophenolate mofetil on the disposition of basiliximab in renal transplant patients

Pharmacokinetic sampling was performed in two multicenter trials in which basiliximab (anti-CD25 monoclonal antibody) was administered with triple immunosuppression consisting of cyclosporine microemulsion, corticosteroids, and either azathioprine or mycophenolate mofetil. Blood samples were collected over 12 wk post-transplant from 31 azathioprine-treated and 66 mycophenolate mofetil-treated patients. Empirical Bayes estimates of each patient's basiliximab disposition parameters were derived and the duration of CD25 saturation was estimated as the time over which serum concentrations exceeded 0.2 microg/mL as confirmed by flow cytometry measurements. Basiliximab clearance was 29+/-14 mL/h when coadministered with azathioprine and 18+/-8 mL/h with mycophenolate mofetil. Both were significantly lower compared with a clearance of 37+/-15 mL/h from a previous study of basiliximab with dual therapy (p<0.001). As a consequence of the lower clearance of basiliximab, the durations of CD25 saturation were prolonged in the presence of azathioprine (50+/-20 d; range, 13--84) and mycophenolate mofetil (59+/-17 d; range, 28--94) compared with dual therapy (36+/-14 d; range, 12--91). A total of 27 acute rejection episodes occurred during the first 6 months in the two studies. Durations of CD25 saturation were not different in these patients compared with those who remained rejection-free in each study. A single patient among 57 who were screened developed anti-idiotype antibodies to basiliximab. The average duration of CD25 saturation was prolonged by 39 and 64% in the presence of azathioprine and mycophenolate mofetil, respectively. This graded effect was also observed for basiliximab clearance and may be due in part to a differentially reduced humoral response to basiliximab. Nonetheless, the range of CD25 saturation durations and basiliximab clearances did not extend outside the range when basiliximab was used with dual therapy in the absence of these agents. Hence, no dosing adjustment is deemed necessary when basiliximab is used in triple immunosuppressive therapy including either azathioprine or mycophenolate mofetil.     

Mycophenolate mofetil vs. azathioprine is associated with decreased acute rejection, late acute rejection, and risk for cardiovascular death in renal transplant recipients with pre-transplant diabetes

Outcomes specifically in mycophenolate mofetil (MMF)-treated diabetic renal transplant patients have not been previously reported. This study compared acute rejection (AR), late acute rejection (LAR), patient survival [and specifically death from cardiovascular (CV), infectious and malignant causes], incidence of post-transplant malignancies, and graft loss in MMF- or azathioprine (AZA)-treated renal transplant patients with pre-transplant diabetes. Outcomes were compared between MMF- (n = 14 144) and AZA- (n = 3001) treated diabetic patients using the Scientific Registry of Transplant Recipients data on all U.S. adult renal transplants performed between 1995 and 2002. Statistical analyses included Kaplan-Meier survival analysis, Cox multivariable regression and chi-square tests. MMF patients had less AR compared with AZA-treated patients (23.5% vs. 28.3%, p < 0.001) and less risk for LAR over 4 yr [hazard ratio (HR): 0.64, 95% CI 0.44, 0.92; p = 0.02]. While time to any-cause death did not differ between the groups, MMF treatment was associated with a 20% decreased risk of CV death (HR: 0.80, 95% CI 0.67, 0.97; p = 0.020) compared with AZA treatment. MMF patients also had a lower incidence of malignancies than AZA patients (2.2% vs. 3.7%, p < 0.001). These results suggest treatment with MMF compared with treatment with AZA in diabetic transplant patients is associated with less AR, less risk of LAR, a decreased risk of CV death, and a lower incidence of malignancies.     

The influence of mycophenolate mofetil on the incidence and severity of primary cytomegalovirus infections and disease after renal transplantation.

BACKGROUND: Mycophenolate mofetil (MMF) is increasingly used for immunosuppression after renal transplantation (RTx). The aim of our study was to investigate if the use of MMF has resulted in an increase in the frequency and severity of primary cytomegalovirus (CMV) infections. METHODS: Retrospective study of adult RTx patients who were CMV seronegative and who received a kidney of a CMV seropositive donor in the period 1992-1997 (n=84). Twenty-four of these patients were treated with MMF (in combination with cyclosporin and prednisone; MMF+) and the other 60 were the control group (cyclosporin and prednisone; MMF-). No CMV prophylaxis was given. CMV infection was defined as CMV seroconversion of IgG antibodies. CMV disease was defined as CMV infection and fever in combination with one or more of the following: leukocytopenia, thrombocytopenia, elevated alanine aminotransferase, or histological evidence of tissue invasive disease. RESULTS: The incidence of primary CMV infections was similar in both groups (MMF+, 75%; MMF-, 63%). CMV disease was more frequent in the MMF+ group than in the MMF- group (67 vs 30%, P<0.05). In the patients with CMV disease, the use of MMF did not affect severity of symptoms, frequency of tissue invasive disease, or frequency or duration of treatment with ganciclovir. CONCLUSIONS: Addition of MMF to the immunosuppressive therapy after RTx did not result in an increase of primary CMV infections.However, these CMV infections led more often to CMV disease in patients treated with MMF than in those without MMF.     

Mycophenolate mofetil for the prophylaxis of acute GVHD in HLA-mismatched bone marrow transplant patients

Mycophenolate mofetil (MMF), a new immunosuppressive drug successfully used in renal and heart transplant recipients, was used in combination with cyclosporin A (CsA), methotrexate (MTX) and prednisolone for the prophylaxis of acute graft-versus-host disease (aGVHD) after bone marrow transplantation (BMT) and peripheral blood stem cell transplantation (PBSCT) from human leukocyte antigen (HLA)-mismatched, unrelated (n = 9) and related donors (n = 4) in an open single-centre phase II study. Thirteen patients, transplanted from HLA-mismatched donors of 18-57 yr of age, received 1 g MMF daily, starting at day 10, in addition to CsA and prednisolone for aGVHD prophylaxis. All patients were engrafted between days 13 and 15. Four of the 13 patients experienced aGVHD grade I/II (n = 2) and grade III (n = 2). All patients except 3 were alive on day 100 post-transplantation. No severe adverse effects of MMF were recorded. In our pilot study, we demonstrated that MMF can be used safely for the prophylaxis of aGVHD.     

Mycophenolate mofetil is associated with less death with function than azathioprine in cadaveric renal transplantation.

BACKGROUND: A previous study has argued that mycophenolate mofetil (MMF) is associated with a reduced incidence of death with function when compared to azathioprine (AZA) in cadaveric renal transplantation. This study was designed to verify this result because methodological issues bring these findings into question. METHODS: The data used in this study was derived from records of renal transplants performed in 1995 and 1996 as recorded in the UNOS Scientific Renal Transplant Registry and supplied by the United States Renal Data System (USRDS). Univariate and multivariate survival analysis was used to compare rates of death with function. Covariate characteristics of the donor, recipient, procedures, early outcomes and the transplant centre were considered. RESULTS: 12,251 recipients of cadaveric renal transplants were identified as having received either MMF or AZA, but not both. The relative risk of death with function calculated by the Kaplan-Meier method was 21% less for MMF patients (P=0.005). MMF had from 21% (P=0.008) to 24% (P=0.001) reductions in relative risk by multivariate methods. CONCLUSIONS: The use of MMF is associated with a reduction in the incidence of death with a functioning graft in cadaveric renal transplantation. These results verify previous analyses.     

Safe conversion of mycophenolate mofetil to azathioprine in kidney transplant recipients with sirolimus-based immunosuppression

Aim:   Mycophenolate mofetil (MMF) is a powerful immunosuppressive drug with established efficacy and safety. The long-term use of MMF may bring increased risk of for infection and malignancy and also increased cost of transplantation. The search for minimization of immunosuppressive protocol has led to an open randomized clinical trial of conversion from MMF to azathioprine (AZA).
Methods:   A total of 50 kidney allograft recipients treated with prednisone, sirolimus and MMF were randomized into two groups: converted (AZA group) and continuing (MMF group). The average duration of MMF therapy prior to conversion was 43 months in each group. Inclusion criteria included: patients with serum creatinine levels of less than 200 µmol/L; no past history of acute vascular rejection or recent acute rejection 6 months before randomization; and normal liver function tests.
Results:   Baseline demographics were similar in the two groups. During the 12 month observation period, there were no acute rejection episodes in either group. There were no significant differences in overall patient or graft survival or function. AZA-treated patients had a lower incidence of gastrointestinal complications ( P  = 0.03). Daily cost reduction in the AZA group was more than $US8.79/day per patient.
Conclusion:   In general, replacing MMF with AZA in stable renal transplant recipients is well tolerated and was cost effective with no increased risk of rejection. As the this study was on relatively small samples, larger and longer follow-up studies will be needed to confirm these expected advantages for the long-term outcome and to assess the long-term safety of this minimization of immunosuppressive therapy.     

Preliminary experience with mycophenolate mofetil for preservation of renal function in cardiac transplant patients with documented cyclosporine nephrotoxicity

BACKGROUND: Cyclosporine (CyA) has positively impacted on the outcome of cardiac transplantation; however, the nephrotoxicity associated with CyA has been a major drawback. METHODS: In an effort to reduce exposure to CyA and possibly alleviate its nephrotoxic effects, we undertook a therapeutic strategy to switch cardiac transplant patients with biopsy-proven CyA nephrotoxicity from azathioprine (AZA) to mycophenolate mofetil (MMF) with subsequent CyA dose reduction or elimination. RESULTS: MMF was substituted for AZA in five cardiac transplant patients (four males; mean age, 60 +/- 6 years old; average time from transplant was 7 +/- 3 years) who had biopsy proven evidence of CyA nephrotoxicity, and in whom CyA dose was reduced (3/5) or discontinued (2/5). At the time of the therapeutic intervention, four patients had an average serum creatinine of 230 +/- 62 micromol/L and one patient had just been started on haemodialysis (HD). During an average follow-up period of 42 months, the slope of the inverse serum creatinine significantly improved in three patients and continued to deteriorate in one patient. The patient on HD could be transiently taken off HD. However, he developed a severe episode of cardiac rejection requiring antirejection therapy and increase in the dose of CyA. The patient was subsequently returned back on HD. CONCLUSION: In this preliminary report, we show that AZA to MMF switch with subsequent CyA dose reduction or discontinuation may slow down the progression of kidney disease in some patients. However, the patients should be followed closely for evidence of cardiac rejection.     

Increased incidence of allograft rejection in stable heart transplant recipients after late conversion from mycophenolate mofetil to azathioprine.

Mycophenolate mofetil (MMF) is a safe and effective immunosuppressive agent in kidney and liver transplantation. Preliminary studies also support its use in heart transplantation. However, the cost of MMF is substantially greater than azathioprine (AZA), the current alternative. Since the majority of rejection episodes occur within the first few months of transplantation, using MMF early after transplantation and subsequently converting to AZA, after the risk of rejection has diminished, might be cost-effective. In order to evaluate the safety of such a strategy in heart transplant recipients, we reviewed the rejection profiles of a group of patients who were converted from MMF to AZA late after transplantation. Forty-three stable patients on chronic MMF therapy as part of an open-label, long-term safety study were converted to either commercially available MMF (CellCept) or AZA, at the conclusion of the study. Demographic variables, rejection histories before and after conversion, and immunosuppressive regimens were examined. Twenty-three patients were continued on commercial MMF and 20 were converted to AZA therapy. The average duration of MMF therapy prior to conversion was 41 months in each group. Baseline demographics were similar in the two groups. Treated allograft rejection occurred in 10 of 20 patients converting to AZA, as compared to only 1 of 23 patients remaining on MMF; p = 0.002. Additionally, mean scores (1-5 scale) for the three biopsies before and after conversion favored continued MMF therapy (1.5+/-0.6 before and 1.2+/-0.4 after conversion in MMF group vs. 1.3+/-0.5 before and 1.7+/-0.9 after conversion to AZA; p = 0.02). No allograft loss occurred as a result of conversion. These data suggest that conversion from MMF to AZA, even late after transplantation, can be associated with allograft rejection. The costs associated with these rejection episodes (the additional immunosuppressive agents, endomyocardial biopsies, and physician visits) may exceed the potential cost savings of converting stable heart transplant recipients from MMF to AZA.     

Mycophenolate mofetil in induction and maintenance therapy of severe lupus nephritis: a meta-analysis of randomized controlled trials.

BACKGROUND: The outcomes of previous trials of mycophenolate mofetil (MMF) in treating severe lupus nephritis (LN) are not in exact agreement. This meta-analysis of randomized controlled trials (RCTs) assesses the benefits and harms of MMF in the induction and maintenance therapy of severe LN. METHODS: We searched Medline, EMBASE and the Cochrane Collaboration Database for RCTs that compared MMF with other immunorepressive regimens for treating lupus nephritis and extracted data for remissions, side effects and prognosis in induction therapy and prognosis and side effects in maintenance therapy, and we summarized the combined results of the data of the RCTs as relative risk (RR). RESULTS: We analysed five RCTs with 307 patients-four RCTS providing the data for comparing MMF with cyclophosphamide (CYC) for induction therapy and two RCTs providing the data for comparing MMF with azathioprine (AZA) for maintenance therapy of severe LN. Overall, compared with CYC, induction therapy with MMF reduced the risk of infection significantly (RR 0.65, P<0.001). It also significantly increased the complete remission rate compared with intravenous CYC (RR 3.10, P=0.006). Compared with intravenous CYC, induction therapy with MMF reduced the incidence of leucopenia significantly (RR 0.66, P=0.04). The prognosis and other side effects were not significantly different between MMF and CYC induction therapies. There was no significant difference between the patients receiving MMF and those receiving AZA for maintenance therapy in prognosis or the risks of amenorrhoea and herpes zoster. CONCLUSIONS: MMF has higher efficacy in inducing remission in severe LN than pulsed intravenous therapy with CYC. Induction therapy with MMF is also associated with fewer side effects than induction therapy with CYC. Compared with AZA, MMF also is an alternative for maintenance therapy of severe LN without significant difference in the prognosis or risks of amenorrhoea and herpes zoster.     

Mycophenolate mofetil treatment for therapy-resistant glomerulopathies

BACKGROUND: The management of steroid-resistant glomerulopathies remains a clinical problem. In this trial, we report a clinical observation of 43 patients treated with mycophenolate mofetil (MMF) for steroid-resistant glomerulopathies. METHODS: All patients underwent renal biopsies, and immunofluorescence and light microscopy examinations were conducted in all cases. All patients had been treated with prednisone at a dose of 1 mg/kg per day for at least 8 weeks. Of the 43 patients, 16 were treated with cyclophosphamide and five were treated with cyclosporine A before MMF started. The primary study outcomes were the change in the urinary protein excretion, serum creatinine, comparing the levels at the start of MMF treatment with those at the end of the MMF treatment period. Changes in renal function were also estimated with Modification of Diet in Renal Failure calculation. Wilcoxon signed-ranks test was used as appropriate to compare data from the start with data at the end of the treatment period. RESULTS: The primary glomerular diseases represented included membranoproliferative glomerulonephritis in 23.2%, membranous glomerulonephritis in 18.6%, IgA nephropathy in 13.9%, focal segmental glomerulosclerosis in 9.3%, lupus nephritis (systemic lupus erythematosus) in 25.6% and pauci-immune glomerulopathy in 9.3% of patients. The mean follow-up time was 28.9+/-12 months. Before MMF treatment, 16 patients (37%) had nephrotic range proteinuria and 11 (26%) had renal insufficiency. The urinary protein before MMF treatment was 3.3+/-2.6 g/dL (0.6-9.6) and decreased significantly to 0.87+/-1.1 g/dL (0-5.5) at the end of the MMF treatment period (P=0.02). During treatment, complete remission was seen in 27 patients, partial remission in 10 patients and MMF failure in six patients. The serum creatinine level decreased significantly from 1.29+/-0.55 mg/dL (0.6-3.0) to 1.14+/-0.38 mg/dL (0.5-2.4) post MMF therapy (P=0.046). Using the four-variable Modification of Diet in Renal Failure formula, the glomerular filtration rate increased from 71.5+/-28 mL/min per 1.73 m2 to 78.1+/-27 mL/min per 1.73 m2 (P=0.021). Renal insufficiency resolved in seven of the 11 (63.6%) patients with renal insufficiency initially, two with membranoproliferative glomerulonephritis, two with membranous glomerulonephritis, one with focal segmental glomerulosclerosis, four with pauci-immune glomerulopathy, two with systemic lupus erythematosus nephritis, and in two patients de novo renal insufficiency developed. CONCLUSION: In general, MMF was well tolerated, and most of the patients achieved remission and improvement of renal functions. MMF treatment appeared to offer benefits to problematic patients refractory to conventional therapies for glomerulopathies.     

Predictors of improvement in renal function after calcineurin inhibitor withdrawal for post-liver transplant renal dysfunction

BACKGROUND: Renal dysfunction after liver transplantation is a major management problem. Predictors of improvement in renal dysfunction after calcineurin inhibitor therapy (CNI) withdrawal and replacement with either mycophenolate mofetil (MMF) or azathioprine (AZA) have not previously been examined. METHODS: Retrospective analysis of 33 post-transplant patients with creatinine clearance (CrCl) below 50 mL/min who were changed from CNI to either MMF or AZA. Following CNI withdrawal patients were divided into two groups: those with improved CrCl after switching and those without, to identify the variables associated with improved renal function. RESULTS: Variables associated with improved CrCl were: absence of hypertension or diabetes, shorter time between transplantation and switch, deterioration in CrCl in months prior to switch and treatment with MMF (compared with AZA). CONCLUSIONS: Our findings suggest CNI withdrawal should be targeted to a subgroup of patients whose renal function is most likely to improve.     

Mycophenolate Mofetil versus Azathioprine in the Maintenance Therapy of Lupus Nephritis

Background. Renal involvement is one of the major determinants of the outcome in patients with systemic lupus erythematosus. Renal involvement contributes to both morbidity and mortality of the patients as well as indirectly through side effects of therapy directed at the renal lesions. The aim of the study was to evaluate the efficacy of mycophenolate mofetil (MMF) and azathioprine (AZA) in the maintenance therapy of lupus nephritis. Methods. Thirty-two patients from our center with diagnosed lupus nephritis World Health Organization Class III, IV, V were treated with IVC (0.75–1g/month) for six months in addition to steroid therapy, and then with AZA (n?=?15) or MMF (n?=?17) as a maintenance therapy. The efficacy of two drugs was compared with changes in serum creatinine, creatinine clearance, 24 hour urine protein excretion, cholesterol, anti-dsDNA antibody, and urine sediment. Results. Mean follow-up time was 41.5 + 7 months. The total remission occurred in 84% of patients (82% with MMF and 87% with AZA), with a complete remission rate of 59.3% (58% with MMF and 60% with AZA) and a partial remission rate of 25% (22% with MMF and 27% with AZA). The urinary protein excretion before MMF treatment was 1.9 + 1 g/dL and decreased significantly to 0.91 + 0.6 g/dL (p?=?0.028) after treatment, and decreased from 1.58 + 0.7g/dL to 0.4 + 0.23g/dL in the AZA group (p?=?0.04). The serum creatinine level decreased from 1.32 + 0.7 mg/dL to 1.12 + 0.68 mg/dL in the MMF group (p?=?0.23), and decreased from 0.91 + 0.23mg/dL to 0.88 + 0.23 mg/dL in the AZA group (p?=?0.49). There was no significant change between two groups (p?=?0.1). The serum cholesterol decreased from 229 + 57 mg/dL to 171 + 9 mg/dL (p?=?0.002), and serum triglyceride level decreased from 228 + 116 mg/dL to 98 + 35 mg/dL (p?=?0.004) in the MMF treatment, but no significant change was seen in AZA group. There was no significant difference between the two groups considering the rates of doubling of serum creatinine, progression to end-stage renal failure, relapses, and documented side effects, as well. Conclusion. Both therapeutic approaches with MMF or AZA, in combination with corticosteroids, are effective as a maintenance therapy for lupus nephritis.     

Effect of prophylactic ganciclovir on cytomegalovirus infection in renal transplant recipients

Cytomegalovirus (CMV) infection is the most frequent infectiouscomplication observed in renal transplant recipients and inducesa significant morbidity in these patients due to CMV diseaseitself and to associated renal dysfunction or opportunisticsuperinfection. In order to evaluate the effect of ganciclovirprophylaxis we conducted an open-label prospective randomizedstudy of ganciclovir administration in CMV seronegative recipientsof a renal allograft from CMV seropositive donors. Ganciclovir(5 mg/kg b.i.d./day for 14 days) was started on day 14 aftertransplantation. Thirty-two patients were included in this study(15 in the control group, 17 in the ganciclovir group). Therewas no significant difference between the two groups for age,immunosuppressive regimen, number of rejection, steroid pulses,and OKT3 treatments. Renal and patient outcomes were similarin both groups. The rate of CMV infection and CMV disease weresimilar in both groups (80% and 73.3% in the control group versus70.6% and 47.1% in the ganciclovir group; P=NS). Less severeCMV disease was observed in the ganciclovir group compared tocontrols. The delay between transplantation and CMV infectionwas significantly longer in the ganciclovir group compared tocontrol group (68.1±5.1 versus 44.0±5.2 days,P<0.005). Twelve control patients (80%) versus nine (53%)of the ganciclovir group required curative treatment with ganciclovirafter the diagnosis of CMV infection (NS). All the patientsrecovered from CMV disease and no significant side-effect wasobserved during ganciclovir administration. We conclude that prophylactic ganciclovir administration fromday 14 to day 28 after transplantation does not prevent CMVinfection in seronegative recipients of renal allograft fromseropositive donors but prolongs the incubation period. Longerprophylaxis by ganciclovir in these patients should be tested.     

Mycophenolate mofetil impairs the integrity of colonic anastomosis

BACKGROUND: The aim of this experimental study was to investigate the effect of mycophenolate mofetil (MMF) during the three phases of colonic anastomosis healing and specifically to check the effect of MMF on the expression of transforming growth factor-beta1 (TGF-beta1), one of the most important growth factors contributing to mechanical stability of colonic anastomosis. MATERIALS AND METHODS: Sixty male Wistar rats underwent colonic resection and end-to-end anastomosis. The animals were divided into two groups, a study group given MMF 40 mg/kg, intraduodenally and a control group given vehicle. The rats were sacrificed at 3, 7, and 14 days (10 animals in each group). The anastomoses were tested by measuring bursting pressure and hydroxyproline content. Histological examination and immunohistochemical expression of TGF-beta1 also were assessed. RESULTS: The mean bursting pressure in the study group was significantly lower on day 3 and 7, but there was no statistical significance on day 14. The mean hydroxyproline content was lower in the study group on days 3, 7, and 14. Histology showed decreased number of macrophages and fibroblasts on days 3 and 7 but no difference on day 14. The expression of TGF-beta1 was significantly reduced in the study group, with the difference being more pronounced on days 3 and 7. CONCLUSION: MMF weakens the integrity of colonic anastomosis, and this effect is more significant during the inflammatory phase of healing. MMF has a negative effect on macrophages and TGF-beta1 expression, resulting in decreased collagen accumulation at the anastomosis.