Background: Paroxysmal supraventricular tachycardia (PSVT) is a heart rhythm disorder characterized by episodes of regular tachyarrhythmia with abrupt onset, often requiring treatment in a hospital setting. Etripamil is a rapidly absorbed, non-dihydropyridine L-type calcium channel blocker currently under investigation for intranasal self administration to terminate acute episodes of PSVT. Objective: To estimate the budget impact of including etripamil in a drug formulary during the first 3 years after market entry from a commercial US payer perspective. Methods: A model was developed in Microsoft Excel to assess differences in health care costs in a hypothetical 1-million-member commercial health plan over a 3-year period. The model considered a scenario with etripamil post-market entry versus the scenario without etripamil. The model considered drug acquisition costs and costs associated with inpatient, emergency department, outpatient hospital, and catheter ablation use. PSVT-eligible patients, visit rates, and visit costs were obtained from published literature and ICD-9/ICD-10 administrative claims databases. Reductions in health resource use were based upon the phase 3 NODE-301,RAPID, and NODE-303 trials as well as qualitative research with physicians. Market uptake for etripamil was assumed at 10%, 25%, and 55% based upon physician qualitative research. All costs were reported undiscounted in 2024 USD. One-way sensitivity analyses were conducted for each hypothetical health plan with inputs varied by ±10%. Results: An estimated 1,900 adult patients in the health plan were eligible for etripamil treatment each year. Over 3 years, the etripamil scenario was associated with an estimated 73 fewer inpatient hospital admissions, 159 fewer emergency department visits, 85 fewer outpatient hospital visits, and 36 fewer catheter ablations. The total drug acquisition and administration costs were $592,800, $1,490,892, and $3,299,642 during years 1-3, respectively. The incremental per-member per-month budget impact in a commercial plan was $0.01 in Year 1 and $0.03 in Year 3. Results were sensitive to the number of yearly treated episodes, etripamil packs per episode, and etripamil pack costs, as well as rate and cost of inpatient admissions. Conclusions: The introduction of etripamil is associated with minimal, balanced budget impact in a commercial health plan over 3 years, with drug acquisition costs offset by reductions in emergency department, inpatient, outpatient hospital, and catheter ablation use. Sponsorship: Milestone Pharmaceuticals Inc.