A method of screening a compound or a compositionfor use in modulating opioid withdrawal symptoms in a mammal. Themethod comprises the steps of: selecting a group of test animals；separating the group into two subgroups； inducing pannexin -1 activationor expression in both subgroups； dosing a first subgroup with a candidatecompound； dosing a second subgroup with a placebo； measuringATP released in spinal microglia of test animals from both subgroups；quantifying the difference in ATP released in spinal microglia of testanimals from the first subgroup and the second subgroup； if the differencein the ATP released in the first subgroup and the ATP releasedin the second subgroup is greater than 25%, then formulating the candidatecompound into a pharmaceutical composition. Also disclosed,pharmaceutical compositions for modulating opioid withdrawal symptomsin a subject comprising a pannexin- 1 inhibitor. Said inhibitormay be 1Opanx peptide with amino acid sequence WRQAAFVDS Y,mefloquine or probenecid.
