Reduction of primary postoperative adhesion formation under calcium channel blockade in the rabbit.

Preliminary studies in a hamster model have demonstrated calcium channel blocking agents to be potent inhibitors of primary post-traumatic peritoneal adhesion formation. The present investigation was designed to extend these observations to an extensively studied model, the rabbit, and to evaluate the optimal route of administration of these drugs for intraabdominal surgery. Rabbits were subjected to a standardized traumatic lesion of the left uterine horn. Subsequently, animals were divided into the following treatment groups: subcutaneous vehicle control (n = 7), intraperitoneal (ip) vehicle control (n = 8), subcutaneous verapamil treatment (n = 6), low-dose (2.5 micrograms/kg/hr) ip verapamil treatment (n = 10), and high-dose ip (25 micrograms/kg/hr) verapamil treatment (n = 6). All animals were reexplored at 1 week postop for evaluation of adhesion formation (scale: 0 to 4+). Calcium channel blockade-treated animals formed significantly fewer adhesions (0.45) than controls (3.93) (P less than 0.01). There was no significant difference between animals treated with sc with verapamil sc and those treated with low- or high-dose verapamil ip (0.33 vs 0.20 vs 1.0). These data confirm our preliminary results, suggesting that calcium channel blockade potently modulates peritoneal healing and regeneration. Furthermore, intraperitoneal delivery and systemic administration appear equipotent in this model. Further study of these agents as potential adjuvants for intraperitoneal surgery is indicated.