Treatment with KF reverses CFA-induced mechanical allodynia in CD-1 mice. Mechanical allodynia produced by CFA (A) but not SNI (B) is reversed by treatment with 4.5 mg/kg KF but not by saline (n = 10 mice/drug). Bars represent mean ± SEM ipsilateral hind paw withdrawal threshold at baseline (BL), 3 days after CFA (pre-injection; Pre), and 30 minutes post-injection of KF (Post). (C) Degranulation of MCs in CFA-treated animals is prevented by treatment with 4.5 mg/kg KF (n = 4). Bars represent means ± SEM percent of degranulated MCs 3 days after SHAM, 3 days after CFA (pre-injection; Pre), and 30 minutes post-injection of KF (Post). (D-F) Representative images of toluidine blue–stained skin sections. Red arrows point to degranulated MCs. *P < 0.05, **P < 0.01 as indicated; CFA, complete Freund's adjuvant; KF, ketotifen fumarate; MC, mast cell; n.s., not significant; SNI, spared nerve injury.