This is a Phase 2, randomized, double-blind, active-controlled, dose-escalation study evaluating the safety, pharmacokinetics, efficacy, and pharmacodynamics of ALX006, an extended-release bupivacaine formulation, administered as a single-dose sciatic nerve block in the popliteal fossa in adult subjects undergoing primary unilateral bunionectomy. Approximately 60 subjects will be enrolled across 3 sequential dose cohorts (100 mg, 150 mg, 200 mg ALX006), with each cohort comparing ALX006 against MARCAINE 0.25% (bupivacaine HCl 50 mg) as the active comparator at a 3:1 randomization ratio. Dose escalation between cohorts is governed by an Independent Data Monitoring Committee.