This invention relates to a method for inhibiting a decrease in the transdermal flux of an agent that is being transdermally delivered or sampled over a prolonged period of time wherein the delivery or sampling involves disrupting at least the stratum corneum layer of the skin to form pathways through which the agent passes. The desired result is achieved by co-delivering or co-sampling the agent with an amount of at least one anti-healing agent wherein the amount of the anti-healing agent is effective in inhibiting a decrease in the agent transdermal flux compared to when the delivery or sampling of the agent is done under substantially identical conditions except in the absence of the anti-healing agent(s).