A Dose-Response Study of Orally Administered Clonidine as Premedication in the Elderly: Evaluating Hemodynamic Safety

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Abstract

Clonidine premedication in a dose of 5 μg/kg may be particularly well suited for elderly patients. To pursue this approach, sedation, intraocular pressure (IOP), and the hemodynamic profile of two doses of oral clonidine premedication were compared in 60 elderly patients, aged 65–82 yr, who underwent elective ophthalmic surgery under local anesthesia. Group 1 (n = 20) received placebo, Group 2 (n = 20) 150 μg of clonidine (2–2.5 μg/kg), and Group 3 (n = 20) 300 μg of clonidine (4–4.5 μg /kg) in a randomized, double-blind fashion. Decreases in mean arterial blood pressure were more pronounced and occurred earlier after 300 μg of clonidine (31.4 ± 12.1%, P < 0.001) as compared to 150 μg of clonidine (18.1 ± 10.9%, P < 0.001). Throughout the study, six patients (30%) in Group 3 (300 μg clonidine-treated group), but no patient in Groups 1 or 2, were treated at least once for hypotension (P < 0.05). Heart rate decreased significantly 18.5 ± 8.1% (P < 0.001) only after 300 μg of clonidine, Clonidine 150 μg and 300 μg decreased IOP 32.1 ± 14.3% (P < 0.001) and 47.8 ± 17.2% (P < 0.001), respectively. After 150 μg of clonidine patients were significantly more sedated as compared to those given placebo (P < 0.01) but significantly less sedated than after 300 μg of clonidine (P < 0.01), where sedation persisted more than 6 h postoperatively. These results suggest that a dose of 150 μg of clonidine, given orally 90–120 min preoperatively to elderly patients managed with local anesthesia, is as effective as a dose of 300 μg in decreasing IOP perioperatively, without causing excessive hemodynamic depression and sedation.

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