Nested Liposomes Extend Nerve Blocks in Rats to Three Weeks

Researchers at Boston Children's Hospital and Harvard Medical School developed an injectable tetrodotoxin formulation using nested liposome compartments that blocked rat sciatic nerves for up to 13 days at 260 mcg, with full sensation returning over two to three weeks. A commercial comparator lasted only four to eight hours. The preclinical study was published Sept. 23, 2026, in Nature Biomedical Engineering.

• 260 mcg dose produced a median nerve block of about 13 days; 80 mcg about 6.5 days
• Commercial comparator formulation blocked nerves for only four to eight hours
• No local or systemic toxicity observed in tested rats
• Platform could deliver other hydrophilic drugs beyond tetrodotoxin