ACE inhibitors notoriously cause hyperkalemia, but interestingly in ESRD patients they may cause development of erythropoietin resistance [71]. N-acetyl-seryl-aspartyl-lysyl- proline (AcSDKP) is a physiological inhibitor of hematopoi- esis [72] and is degraded by ACE. AcSDKP accumulates in patients with ESRD and may explain erythropoietin hypo- responsiveness, particularly in patients treated with ACE inhibitors [23]. In addition, a high incidence of anaphylactoid reaction with the AN69 dialyzer has been reported in ESRD patients on ACE inhibitors.
Another option available is the weekly application of a transdermal clonidine patch [73]. Minoxidil, a potent vasodilator, may also be used, but caution should be observed as they are normally excreted through the kidneys [74] and it should be used with a beta blocker to maintain efficacy. Its main side effects include hirsutism, pericardial effusion, and edema, which can be problematic in dialysis patients. Most ACE inhibitors as well as beta blockers are removed with dialysis, while CCBs and ARBs are not and are of particular sig- nificance especially for patients exhibiting a renin-dependent form of hypertension, ie, blood pressure rises throughout the hemodialysis procedure with higher posthemodialysis renin levels than prehemodialysis (Table 2).