Haemorrhagic
diathesis develops in
chronic renal failure, in which
calcium antagonists are used widely as
antihypertensive agents. Although
calcium antagonists are reported to impair platelet function, it has not been examined whether
calcium antagonists alter bleeding time. The present study was conducted to clarify whether
calcium antagonists affect bleeding time in
chronic renal failure. Patients with
chronic renal failure without and with
calcium antagonists were enrolled (n = 156), and bleeding time (Ivy's method) as well as blood parameters (BUN,
creatinine, platelet counts, and haemoglobin) were compared in patients with normal and prolonged bleeding time. Among patients not taking
calcium antagonists (n = 34), three cases manifested prolonged bleeding time, whereas abnormal bleeding time was observed in 31 patients out of 122. Positive correlations were observed between bleeding time and BUN in both
calcium antagonist-untreated (r = 0.46) and -treated groups (r = 0.25). The odds ratio for prolongation of bleeding time in patients taking
calcium antagonists was 3.52 (95% CI, 1.01-12.33). In 12
calcium antagonist-treated patients with prolonged bleeding time, the withdrawal of
calcium antagonists markedly shortened bleeding time (from 11.3 +/- 0.8 to 5.4 +/- 0.8 min, P < 0.05, n = 12). In contrast, in the additional group (n = 9), the continued treatment with
calcium antagonists had no effect on bleeding time (from 11.7 +/- 0.9 to 10.0 +/- 1.0 min). Despite the inhibitory effect of
calcium antagonists on bleeding time, no clinically serious events associated with haemorrhagic
diathesis developed. In conclusion,
calcium antagonists prolong bleeding time in patients with
chronic renal failure. The subclinical (laboratory) effect of
calcium antagonists however is not necessarily associated with haemorrhagic events of clinical significance.