--- title: "Under-Reimbursement: The Gross-to-Net Leak Most Manufacturers Don't See" description: Under-reimbursement is a gross-to-net leak most manufacturers never quantify. How it happens in claims adjudication and how to stop it. image: https://www.infinityrx.com/hubfs/Blog%20Post%20Graphics/The%20GTN%20Leak%20Nobodys%20Measuring.jpg --- InfinityRx made the 2026 Inc. 5000 list. [See our Inc. 5000 ranking](https://www.infinityrx.com/news-insights/infinityrx-named-to-2026-inc5000) [![infinityrx-white](https://www.infinityrx.com/hs-fs/hubfs/Logos/infinityrx-white.png?width=512&height=392&name=infinityrx-white.png)](https://www.infinityrx.com) - [Solutions](https://www.infinityrx.com/solutions) [Claims Program Administration Pharmacy and medical benefit copay through one proprietary engine.](https://www.infinityrx.com/solutions#powered-by-icp) [Access Services Verify coverage. Accelerate access.](https://www.infinityrx.com/solutions#powered-by-icp) [GTN Protection Protect access. 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[Request a Program Assessment](https://www.infinityrx.com/request-program-assessment) [Submit an RFP →](https://www.infinityrx.com/rfp-submission) - [Insights](https://www.infinityrx.com/news-insights) [All Articles For the teams running patient access programs](https://www.infinityrx.com/news-insights) [Benefit-to-WAC Ratio Understand program stability through Benefit-to-WAC ratio](https://www.infinityrx.com/news-insights/understanding-program-sustainability-through-benefit-to-wac-ratio) [Pharmacy Monitoring Why Real-Time Visibility Beats Reactive Audits](https://www.infinityrx.com/news-insights/pharmacy-monitoring-real-time-visibility) [Unified Dual Benefit Why Pharmacy and Medical Benefits Belong on One Platform](https://www.infinityrx.com/news-insights/unified-dual-benefit-why-pharmacy-and-medical-belong-on-one-platform) [Under-Reimbursement The Gross-to-Net Leak Most Manufacturers Don't See](https://www.infinityrx.com/news-insights/under-reimbursement-the-gross-to-net-leak-most-manufacturers-dont-see) [InfinityRx named No. 156 on the 2026 Inc. 5000 list Read the announcement](https://www.infinityrx.com/news-insights/infinityrx-named-to-2026-inc5000) - [About Us](https://www.infinityrx.com/about) - [Contact Us](https://www.infinityrx.com/contact) [Request a Program Assessment](https://www.infinityrx.com/request-program-assessment) Solutions [Solutions overview](https://www.infinityrx.com/solutions) [Claims Program Administration](https://www.infinityrx.com/solutions#powered-by-icp) [Access Services](https://www.infinityrx.com/solutions#powered-by-icp) [GTN Protection](https://www.infinityrx.com/solutions#powered-by-icp) [Data & Program Intelligence](https://www.infinityrx.com/solutions#powered-by-icp) [Patient Engagement](https://www.infinityrx.com/solutions#powered-by-icp) Insights [Insights overview](https://www.infinityrx.com/news-insights) [All Articles](https://www.infinityrx.com/news-insights) [Benefit-to-WAC Ratio](https://www.infinityrx.com/news-insights/understanding-program-sustainability-through-benefit-to-wac-ratio) [Pharmacy Monitoring](https://www.infinityrx.com/news-insights/pharmacy-monitoring-real-time-visibility) [Unified Dual Benefit](https://www.infinityrx.com/news-insights/unified-dual-benefit-why-pharmacy-and-medical-belong-on-one-platform) [Under-Reimbursement](https://www.infinityrx.com/news-insights/under-reimbursement-the-gross-to-net-leak-most-manufacturers-dont-see) [About Us](https://www.infinityrx.com/about) [Contact Us](https://www.infinityrx.com/contact) [Request a Program Assessment](https://www.infinityrx.com/request-program-assessment) # Under-Reimbursement: The Gross-to-Net Leak Most Manufacturers Don't See [InfinityRx](https://www.infinityrx.com/news-insights/author/infinityrx) Apr 19, 2026 --- [Claims Adjudication](https://www.infinityrx.com/news-insights/tag/claims-adjudication) [Gross-to-Net](https://www.infinityrx.com/news-insights/tag/gross-to-net)   [Copay accumulator](https://www.infinityrx.com/news-insights/the-accumulator-problem-how-manufacturer-dollars-get-diverted-every-year) and [maximizer defense](https://www.infinityrx.com/news-insights/maximizers-the-quieter-more-expensive-threat-to-your-copay-program) gets most of the air in the patient support conversation, and reasonably so — the dollar magnitude is enormous and the visibility is high. But there's a quieter threat to manufacturer economics that rarely gets quantified in the same conversation, and for some specialty brands it's nearly as large. Under-reimbursement. The mechanics are simple. When a pharmacy dispenses a specialty drug, it's reimbursed at a rate determined by the payer — the plan, the PBM, or (in manufacturer copay programs) the copay program itself. That rate is supposed to cover the pharmacy's acquisition cost plus a reasonable dispensing margin. Sometimes it doesn't. When the pharmacy's acquisition cost is higher than the reimbursement it receives, the pharmacy takes a loss on the dispense. Pharmacies don't take losses on dispenses forever. ## What happens when pharmacies stop dispensing When a pharmacy determines that a specific NDC is systematically under-reimbursed, it has options, all of which break the manufacturer's access strategy. 1. **Refuse to dispense.** The patient walks into the pharmacy with a prescription, and the pharmacy tells them it isn't available there. Some come back; some don't. Your new-patient-start rate quietly deteriorates. 2. **Substitute a therapeutic alternative.** The pharmacy contacts the prescriber and suggests an alternate therapy that's more economically viable for the pharmacy. Some prescribers accept the switch. Either way, your market share erodes brand-by-brand without showing up in any single data point. 3. **Stock unreliably.** The pharmacy keeps the NDC on formulary but orders it inconsistently. Adherence suffers. Persistence erodes. Each of these outcomes is the same in effect: your drug doesn't reach the patient who was prescribed it. Your market access strategy — the one that negotiated placement on every formulary that matters — ends up defeated at the dispense counter. ## Why traditional fixes don't scale The historical manufacturer response to under-reimbursement has been two things: pharmacy outreach and distribution strategy. Pharmacy outreach means a manufacturer field rep contacts the pharmacy, discusses the economics, and tries to work out a solution. Labor-intensive. Non-scalable. Gets to a tiny fraction of the pharmacy universe. Distribution strategy means adjusting wholesaler and channel selection to improve acquisition cost. Helps at the margin, but slow, and doesn't address per-claim edge cases. Neither operates in real time, at the claim level, where the problem actually happens. ## What the infrastructure response looks like The scalable response to under-reimbursement is [real-time protection](https://www.infinityrx.com/news-insights/pharmacy-monitoring-real-time-visibility) built directly into the adjudication workflow. When a claim would otherwise leave a pharmacy with negative margin, the platform applies a manufacturer-funded adjustment that brings reimbursement to an acceptable level — inline, inside the same transaction the pharmacy is already processing. The pharmacy's experience is that the claim processed correctly with a reasonable margin. They keep dispensing. Your access strategy stays intact. ## Where this fits in GTN strategy The usual way manufacturers talk about GTN is through the levers of rebate management, copay program design, and accumulator/maximizer defense. Under-reimbursement protection is a fourth lever that doesn't fit cleanly into the others — but its effect on the bottom line can be substantial for specialty brands with tight acquisition-cost margins. For brands where the difference between pharmacy acquisition cost and payer reimbursement is reliably comfortable, the lever is small. For brands where that difference is tight or occasionally negative — which includes many specialty therapies once they're a few years into their lifecycle — the lever is meaningful. The question worth asking, as part of any GTN review, is whether under-reimbursement has ever been explicitly measured [at the claim level](https://www.infinityrx.com/news-insights/program-leakage-a-closed-loop-framework-for-recovery-and-prevention). Most manufacturers haven't measured it, because their claims data doesn't make it visible. Once it's measured, it usually moves the conversation in a direction that wasn't on the agenda going in. --- **Curious whether under-reimbursement is affecting your brand? [Request a program assessment.](https://www.infinityrx.com/request-program-assessment)** ## Related Insights [![Unified Dual Benefit: Why Pharmacy and Medical Belong on One Platform](https://www.infinityrx.com/hs-fs/hubfs/Blog%20Post%20Graphics/InfinityRx%20-%20Why%20Pharmacy%20and%20Medical%20Belong%20on%20One%20Platform.jpg?width=650&height=364&name=InfinityRx%20-%20Why%20Pharmacy%20and%20Medical%20Belong%20on%20One%20Platform.jpg)](https://www.infinityrx.com/news-insights/unified-dual-benefit-why-pharmacy-and-medical-belong-on-one-platform) Claims Adjudication ### [Unified Dual Benefit: Why Pharmacy and Medical Belong on One Platform](https://www.infinityrx.com/news-insights/unified-dual-benefit-why-pharmacy-and-medical-belong-on-one-platform) Gross-to-Net ### [The Accumulator Problem: How Manufacturer Dollars Get Diverted Every Year](https://www.infinityrx.com/news-insights/the-accumulator-problem-how-manufacturer-dollars-get-diverted-every-year) [![Understanding program sustainability through Benefit-to-WAC ratio](https://www.infinityrx.com/hs-fs/hubfs/Benefit%20to%20WAC%20%20ratio%20and%20program%20sustainability.jpg?width=650&height=364&name=Benefit%20to%20WAC%20%20ratio%20and%20program%20sustainability.jpg)](https://www.infinityrx.com/news-insights/understanding-program-sustainability-through-benefit-to-wac-ratio) Claims Adjudication ### [Understanding program sustainability through Benefit-to-WAC ratio](https://www.infinityrx.com/news-insights/understanding-program-sustainability-through-benefit-to-wac-ratio) [![InfinityRx](https://www.infinityrx.com/hs-fs/hubfs/InfinityRx%20logo%20white.png?width=300&height=52&name=InfinityRx%20logo%20white.png "InfinityRx")](https://infinityrx.com) InfinityRx helps pharmaceutical manufacturers administer pharmacy and medical benefit affordability programs, protect GTN performance, and turn claim-level data into better program decisions through InfinityRx Claims Processor®, the adjudication engine we own.  Built in New York. 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