Inter- and intra-site reliability of forearm sweating induced by pilocarpine iontophoresis

We examined the inter- and intra-site reliability of pilocarpine-induced forearm sweat rate at three concentrations. Under thermoneutral conditions, 10 males and 4 females received 0.001%, 0.01%, and 1% pilocarpine via iontophoresis at the lateral and medial left forearm and the medial right forearm. Sweat rate was measured for 30 min. Inter-site (right vs. left medial) and intra-site (left lateral vs. medial) comparisons were assessed using intraclass correlation (ICC) and coefficient of variation (CV). Inter-site comparisons showed significant correlations at 0.01% and 1% (both p < 0.001, r ≥ 0.688) with good agreement (ICC ≥ 0.79, CV ≤ 21.5%), whereas 0.001% showed poorer reliability (CV = 47.3%). Intra-site reliability was highest at 1% (ICC = 0.89, CV = 16.5%) and lower at 0.01% and 0.001%. These findings indicate that inter-site comparisons of pilocarpine-induced sweating at 1% and 0.01% concentrations provide reliable responses for sweat mechanism studies (e.g., with and without antagonist administration).