Diabetics with Hypertension Not Controlled with ACE Inhibitors: Alternate Therapies

If hypertension in patients with diabetes mellitus type II is not adequately controlled by angiotensin-converting enzyme inhibitors (ACE-i), a beta-blocker is frequently added as second- line therapy. Recently, large randomized trials demonstrated the beneficial effect of second- generation dihydropyridine calcium-channel blockers in these patients. These compounds are increasingly being used to replace beta-blockers. Withdrawal of beta-blockers may influence diabetic control and may cause rebound hypertension. Any rebound hypertension from beta- blocker withdrawal may not occur if the beta-blocker is replaced with a calcium-channel blocker. A calcium-channel blocker will influence vascular resistance (VR) and blood pressure differently than a beta-blocker. Thirty-four patients with diabetes mellitus type II and a resting diastolic blood pressure above 90 mm Hg despite enalapril 10 mg daily (or equipotent dosages of other ACE-i) for at least 3 months were treated in an open label sequential comparison with the same ACE-i in combination with the beta-blocker metoprolol 100 mg for 3 months, and, subsequently for 3 more months with the same ACE-i in combination with the dihy dropyridine calcium-channel blocker lercanidipine 10 mg once daily. After 6 weeks, patients with a diastolic blood pressure above 90 mm Hg were titrated up to 200 mg metoprolol or 20 mg lercanidipine once daily. Patients were examined every 6 weeks during the trial, and after 2 weeks while receiving lercanidipine. In addition to blood pressure measurements, VR was measured by iridium strain gauge plethysmography and expressed in units (1 unit = 1 mm Hg/mL blood/100 mL tissue per minute). Two of 34 patients did not complete the protocol because of non-compliance with the lercanidipine treatment in the first 2 weeks of treatment. Their data are included in the analysis. No rebound hypertension 14 days after the change-over of therapies was observed. (Mean arterial pressures [MAPs] were not significantly different from the point of withdrawal of the beta-blockers.) However, heart rate rose from 69 ±7 to 94 ± 10 beats/min (p < 0.001). After 3 months on lercanidipine, MAP fell by 6 ± 10 mm Hg (p = 0.002) compared to the point of withdrawal of the beta-blocker. Vascular resistance fell by 6.28 ± 11.91 units (p