Preoperative Amlodipine Is More Efficacious Than Prazosin in Preventing Intraoperative Haemodynamic Instability in Pheochromocytoma/Paraganglioma Patients: Interim Analysis of a Pilot Randomized Controlled Study

Background: Preoperative blockade with α-blockers is recommended in patients with pheochromocytoma/paraganglioma (PPGL). The data on calcium channel blockade (CCB) in PPGL is scarce. We aim to compare the efficacy of CCB and α-blockers on intraoperative haemodynamic instability (HDI) in PPGL. Methods: In the interim analysis of this monocentric, pilot, open-label, randomized controlled trial, patients with solitary, secretory, and nonmetastatic PPGL were randomized to oral prazosin (maximum 30mg, n=9) or amlodipine (maximum 20mg, n=11). The primary outcomes were the episodes and duration of hypertension (SBP≥160mmHg) and hypotension (MAP<60mmHg) and duration of HDI (hypertension and/or hypotension) as a percentage of total surgical time (from induction of anaesthesia to skin closure). Findings: The median (IQR) episodes (2 [1–3] vs. 0 [0–1], p 0·002) and duration of hypertension (19 [14–42] min vs. 0 [0–3] min, p 0·001) and intraoperative HDI duration (22·85±18.4% vs 2·44±2·4%, CI 8·68-32·14%, p 0·002) were significantly higher in the prazosin arm than the amlodipine arm whereas episodes and duration of hypotension did not differ between the two groups. There was no perioperative mortality whereas one patient had intraoperative ST depression on the electrocardiogram. The drug-related adverse effects were pedal edema (1 in amlodipine), dizziness (1 in prazosin), and tachycardia (6 in prazosin and 3 in amlodipine). Interpretation: Preoperative blockade with amlodipine was more efficacious than prazosin in preventing intraoperative HDI in PPGL. Larger studies that compare preoperative blockade with amlodipine and both competitive and noncompetitive α-blockers inPPGL patients of various biochemical phenotypes are warranted.