The effect of the action of collagenase in treating lesions containing collagen or mixed fibrin clots (e.g., burns or ulcers) is improved by applying collagenase to the wound in combination with an organogel and a phosphatidylcholine, of which lecithin is a readily available source, particularly when the collagenase is first mixed and stored with that choline and an organic solvent and is subsequently mixed with a second individually stored formulation comprising a gel-forming agent and water, the two formulations individually having satisfactory shelf lives and the resultant mixture being applied to the lesion promptly after being formed.