Development of ProTx-II Analogues as Highly Selective Peptide Blockers of Na1.7 for the Treatment of Pain.

Inhibitor cystine knot peptides, derived from venom, have evolved to block ion channel function but are often toxic when dosed at pharmacologically relevant levels . The article describes the design of analogues of ProTx-II that safely display systemic blocking of Na1.7, resulting in a latency of response to thermal stimuli in rodents. The new designs achieve a better profile by improving ion channel selectivity and limiting the ability of the peptides to cause mast cell degranulation. The design rationale, structural modeling, profiles, and rat tail flick outcomes are disclosed and discussed.