Effect of nifedipine on renal transplant rejection

Calcium channel blockers differentially modulate cytokine production by peripheral blood mononuclear cells

BACKGROUND

Calcium channel blockers (CCB) are known to modulate immune reactions, so the present study was performed to examine the effects of various CCBs that have shown different effects on transcription factors and on the production of pro-inflammatory cytokines by human peripheral blood mononuclear cells (PBMC).

METHODS AND RESULTS

PBMC from healthy volunteers were isolated by Ficoll-paque density centrifugation. To study the effect of CCBs, the PBMC were stimulated with lipopolysaccharide or concanavalin A. After 24 h of incubation, the supernatants were harvested and the interleukin (IL)-1alpha, -1beta, and -6, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma levels were determined by specific enzyme-linked immunosorbent assay. The production of IL-1alpha and -1beta stimulated with lipopolysaccharide was significantly increased in the presence of amlodipine. In contrast, nifedipine and verapamil suppressed the production of IL-1beta, TNF-alpha, and IFN-gamma. Amlodipine and diltiazem significantly increased production of IL-1alpha stimulated with concanavalin A. Nifedipine inhibited production of IL-1alpha, IL-6, and IFN-gamma. Verapamil suppressed production of IFN-gamma.

CONCLUSIONS

Differential modulation of cytokine production was seen with various CCBs, and the suppressive effect of nifedipine was most prominent.

Sustained improvement of renal graft function for two years in hypertensive renal transplant recipients treated with nifedipine as compared to lisinopril

BACKGROUND

Treatment of posttransplant hypertension is still a matter of debate. Calcium antagonists may ameliorate renal side effects of cyclosporin. Angiotensin converting enzyme- (ACE) inhibitors may be more effective in sustaining renal function in native chronic renal disease. We prospectively compared the effect of controlled release nifedipine and lisinopril on long-term renal function in hypertensive kidney transplant patients treated with cyclosporin.

METHODS

A total of 154 renal transplant patients presenting with hypertension (diastolic blood pressure >or=95 mmHg) during the first 3 weeks after transplantation were randomised to receive double-blind nifedipine 30 mg or lisinopril 10 mg once daily. A total of 123 patients completed 1 year of treatment (69 nifedipine, 54 lisinopril) and 64 patients completed 2 years of double-blind treatment (39 nifedipine, 25 lisinopril). Baseline glomerular filtration rate was measured as 99 mTc-diethylene-triaminepentaacetate clearance in a stable phase 2 to 5 weeks after inclusion and repeated at 1 and 2 years.

RESULTS

Baseline glomerular filtration rates were similar (46+/-16 ml/min with nifedipine, 43+/-14 ml/min with lisinopril). The changes in glomerular filtration rates from baseline were statistically significant between the groups after 1 year (9.6 ml/min mean treatment difference (95% confidence interval [CI]s 5.5-13.7 ml/min, P=0.0001) and remained statistically significant also after 2 years (10.3 ml/min mean difference (95% CIs 4.0-16.6], P=0.0017). After 1 year glomerular filtration rates averaged 56+/-19 ml/min in the nifedipine group and 44+/-14 ml/min in the lisinopril group.

CONCLUSIONS

Both nifedipine and lisinopril were safe and effective in treatment of hypertension in renal transplant patients treated with cyclosporin. Patients receiving nifedipine but not lisinopril improved kidney transplant function over a period of 2 years.

A comparison of observational studies and randomized, controlled trials

BACKGROUND

For many years it has been claimed that observational studies find stronger treatment effects than randomized, controlled trials. We compared the results of observational studies with those of randomized, controlled trials.

METHODS

We searched the Abridged Index Medicus and Cochrane data bases to identify observational studies reported between 1985 and 1998 that compared two or more treatments or interventions for the same condition. We then searched the Medline and Cochrane data bases to identify all the randomized, controlled trials and observational studies comparing the same treatments for these conditions. For each treatment, the magnitudes of the effects in the various observational studies were combined by the Mantel-Haenszel or weighted analysis-of-variance procedure and then compared with the combined magnitude of the effects in the randomized, controlled trials that evaluated the same treatment.

RESULTS

There were 136 reports about 19 diverse treatments, such as calcium-channel-blocker therapy for coronary artery disease, appendectomy, and interventions for subfertility. In most cases, the estimates of the treatment effects from observational studies and randomized, controlled trials were similar. In only 2 of the 19 analyses of treatment effects did the combined magnitude of the effect in observational studies lie outside the 95 percent confidence interval for the combined magnitude in the randomized, controlled trials.

CONCLUSIONS

We found little evidence that estimates of treatment effects in observational studies reported after 1984 are either consistently larger than or qualitatively different from those obtained in randomized, controlled trials.

The beneficial effects of calcium channel blockers on long-term kidney transplant survival are independent of blood-pressure reduction

There is a growing body of evidence suggesting that calcium channel blockers (CCB) exert beneficial effects on kidney transplant survival. However, it is not completely understood if these agents act independently of blood-pressure reduction. In the present study, the 5-yr follow-up of 45 kidney transplant recipients receiving CCB during the 60-month follow-up period was compared to that of recipients with lower blood pressure and an antihypertensive treatment without CCB. During the whole follow-up, systolic (127.4 +/- 2.5 vs. 139.4 +/- 2.1 mmHg, p < 0.05) as well as diastolic blood pressure (78.8 +/- 1.1 vs. 84.8 +/- 1.8 mmHg, p < 0.05) was higher in the group receiving CCB. Moreover, in CCB-treated recipients, a significant (p < 0.05) higher increase in proteinuria was detected (from 759 +/- 120 to 1690 +/- 359 mg/24 h vs. 180 +/- 45 to 340 +/- 45 mg/24 h). Despite higher blood pressure and higher proteinuria, the increase in serum creatinine in the group of CCB-treated recipients was significantly lower (0.01 mg/dL/month) in comparison to that of the controls (0.02 mg/dL/month, p < 0.05). Moreover, the 5-yr transplant survival was significantly higher in CCB-treated recipients (62.3 vs. 31.8%, p < 0.05). The results of the present study further support the beneficial effects of CCB in kidney transplant recipients, which are independent of blood-pressure reduction.