Thirty-five adult male Wistar rats ( 200 - 250 g ) were randomly divided into 5 groups : loperamide HCl-encapsulated liposomal gel , naloxone methiodide + loperamide HCl-encapsulated liposomal gel , free loperamide gel , empty liposomal gel , and 1 % diclofenac gel ( Voltaren ) .