Background and purpose: αO-conotoxin GeXIVA[1,2], a natural peptide discovered by our laboratory from Conus generalis in the South China Sea, is a novel nonaddictive analgesic targeting the α9α10 nicotinic acetylcholine receptor (nAChR). This study aimed to elucidate the underlying mechanisms by the disposition and modelling of GeXIVA[1,2]. Experimental approach: The pharmacokinetics (PK) of GeXIVA[1,2] and tissue distribution in rats and dogs were studied. A population pharmacokinetics model and a pharmacokinetic-pharmacodynamic model were developed based on animal data and used to predict the efficacious dose in humans and explain the mechanism. Key results: The intramuscular bioavailability of GeXIVA[1,2] was 11.47% and 13.37% in rats and dogs, respectively. Across experimental doses, the plasma exposure increased approximately in proportion to dose, and the half-life of GeXIVA[1,2] ranged from 5.37±0.99 to 19.65±6.21 min. GeXIVA[1,2] had less extensive tissue distribution. The bound fractions differed in human, rat, and dog plasma, ranging from 55.85±5.10% to 87.64±7.49%. The one-compartment model with the first-order absorption PPK model estimated an efficacious dose of 11.9-30.8 μg·kg-1 in a 70 kg human with bodyweight as a covariant. The inhibitory loss indirect response model combined with an effect compartment adequately described PK-PD relationships. Conclusion and implications: We speculated that GeXIVA[1,2] exerts analgesia by inhibiting the elimination of certain endogenous substances, which may be a key pharmacodynamic biomarker. This is the first report of the disposition of conotoxin-derived therapeutic agents and possible analgesic mechanisms of α9α10 nAChR, which were elucidated by PK studies and modelling approaches.