1. Executive Summary and Strategic Context

The GUARD Model is a proposed mandatory Medicare Part D drug pricing demonstration testing international pricing benchmarks for calculating inflation rebates on prescription drugs. Published as an NPRM on December 23, 2025 (90 Fed. Reg. 60,338), GUARD would operate from January 1, 2027 through December 31, 2033, with rebate settlement extending to December 2035.

GUARD is the Part D companion to GLOBE (Part B). Both use Section 1115A authority to implement Most Favored Nation (MFN) pricing through modified inflation rebate calculations. GUARD targets sole-source drugs and sole-source biologics across 17 therapeutic categories (broader than GLOBE's 7 categories), applying to approximately 25% of Part D beneficiaries in randomly selected geographic areas.

1.1 Strategic Significance

GUARD operates within the existing IRA Part D inflation rebate framework, modifying how rebates are calculated rather than creating a new rebate obligation. By benchmarking against international prices rather than domestic inflation-adjusted prices, GUARD could generate substantially larger manufacturer rebates. CMS projects combined GLOBE+GUARD savings of approximately $26 billion. However, GUARD lacks GLOBE's direct beneficiary coinsurance reduction mechanism, meaning out-of-pocket cost reductions for Part D beneficiaries are less certain.

2. Model Architecture

2.1 Regulatory Framework

Authority: Section 1115A of the Social Security Act.

NPRM: December 23, 2025 (90 Fed. Reg. 60,338). Comments due February 23, 2026.

Proposed Start: January 1, 2027.

Performance Period: January 1, 2027 - December 31, 2033 (7 years including reconciliation).

Rebate Settlement: Through December 31, 2035.

Type: MANDATORY for qualifying manufacturers.

2.2 Eligible Drugs - 17 Therapeutic Categories

GUARD covers significantly broader therapeutic categories than GLOBE: Analgesics, Anticonvulsants, Antidepressants, Antimigraine Agents, Antineoplastics, Antipsychotics, Antivirals, Bipolar Agents, Blood Glucose Regulators, Cardiovascular Agents, Central Nervous System Agents, Gastrointestinal Agents, Genetic/Enzyme/Protein Disorder treatments, Immunological Agents, Metabolic Bone Disease Agents, Ophthalmic Agents, Respiratory Tract/Pulmonary Agents.

Exclusions: Sole-source generics, biosimilar biological products, drugs selected for Medicare Drug Price Negotiation (when MFP is in effect).

2.3 Benchmark Methodology

Same 19 OECD reference countries as GLOBE. Same two-method approach (CMS-derived vs. manufacturer-submitted international pricing). GUARD rebate = difference between Medicare net price (WAC minus Part D DIR minus manufacturer discount program payments) and international benchmark, to the extent exceeding existing IRA inflation rebate.