X0508 4 2023-10-27 0001811623 PaxMedica, Inc. PXMD 0001940128 Coelho John F C/O PAXMEDICA, INC. 303 SOUTH BROADWAY, SUITE 125 TARRYTOWN NY 10591 1 0 0 0 1 Common Stock 2023-10-27 4 S 0 570 0.1895 D 79090 D The sales reported in this Form 4 were effected pursuant to the Reporting Person's pre-existing Rule 10b5-1 trading plan to, inter alia, pay tax withholding on vested RSUs. The sale price represents the weighted average sale price of the shares sold ranging from $0.187 to $0.1901 per share. Upon request by the Commission staff, the Issuer, or a security holder of the Issuer, the reporting person will provide full information regarding the number of shares sold at each separate price within the range set forth in this Form 4. Does not reflect a 1-for-17 reverse stock split effective October 30, 2023. /s/ Stephen D. Sheldon, Jr. Attorney-in-Fact 2023-10-30