How Hospitals Actually Buy Drugs: GPOs, Wholesalers and Direct Contracts

rgultig

July 29, 2026

The channel where half of US pharmaceutical spending flows — and why a hospital’s drug procurement officer has almost no direct relationship with manufacturers.

A hospital pharmacy director does not call Merck or Pfizer to buy insulin. They do not negotiate directly with suppliers. Instead, a complex three-layer system sits between the hospital and the manufacturer: Group Purchasing Organizations (GPOs) that consolidate buying power, pharmaceutical wholesalers that distribute the products, and an overlay of specialty pharmacies, direct contracts, and the 340B program that fragments the channel in ways that create opaque pricing and hidden incentives.

This report maps that channel: who controls what, where the leverage sits, and why a hospital’s drug procurement strategy is less about choosing drugs and more about navigating a system designed by profit-optimizers, not clinicians.

Layer 1: GPOs — the invisible negotiators

A Group Purchasing Organization (GPO) is a middleman that pools the purchasing volume of many hospitals and healthcare providers to negotiate lower prices from manufacturers and suppliers. A hospital joins a GPO, pays membership fees (typically low or zero), and gains access to a portfolio of pre-negotiated contracts with drug makers, device manufacturers, and service providers.

GPOs control roughly 65% of all hospital and healthcare product purchasing. The market has consolidated dramatically. In 1994, there were 56 significant GPOs. Today, the six largest GPOs negotiate contracts for about 80% of the nation’s 5,400 acute-care hospitals. Vizient (the largest), Premier Inc., and Medline (primarily devices, but growing into pharma) are the dominant players.

The value proposition is simple: volume. A hospital alone has limited negotiating power. A GPO representing 500 hospitals can threaten to exclude a manufacturer from thousands of beds. Manufacturers therefore offer GPOs deeper rebates, better pricing, and favorable contract terms than hospitals could achieve independently. GPOs claim to deliver 15-20% savings versus individual negotiation, though that claim is disputed and depends heavily on which products and which hospitals you examine.

GPOs make money primarily through administrative fees paid by members and fees paid by suppliers for contract access. This fee-for-contract model creates an incentive misalignment: a GPO earns money when a product gets a contract slot, regardless of whether that product is the lowest-cost option for members. Regulators and hospital purchasing consortiums have scrutinized this model for decades.

Layer 2: Wholesalers — the physical gatekeepers

Pharmaceutical wholesalers are the actual distributors. The industry is an oligopoly: McKesson, Cencora (formerly AmerisourceBergen), and Cardinal Health control over 90% of the market by volume. Combined, they shipped roughly $776 billion in pharmaceutical products in 2024 across all channels — retail, hospital, mail-order, specialty.

Each of the Big Three runs massive national distribution networks: tens of millions of square feet of warehouse space, computerized logistics systems, and delivery fleets reaching all 50 states. A hospital’s pharmacy receives shipments from one of these three wholesalers multiple times per week.

Wholesalers are margin-squeezed. Since 2015, despite revenues rising by over $100 billion (from ~$358B to ~$458B), gross profit dollars actually fell by about 12%. This is the classic dynamics of generic drugs: volume grows, margins compress. In response, wholesalers are:

Expanding specialty services. They are building cold-chain infrastructure, patient management programs, and specialty pharmacy networks to capture higher margins on biologics and rare-disease drugs. AmerisourceBergen has invested heavily in specialty distribution centers.

Vertically integrating. All three are now buying into specialty medical practices (oncology, ophthalmology, urology), specialty pharmacies, and patient support programs. They are no longer just distributors; they are operators.

Shifting whichever customers they can. When Cardinal Health lost its OptumRx business in 2023-24 (representing 16% of Cardinal’s revenue), it shifted that volume to other buyers and raised prices on remaining customers. Wholesalers have pricing power with small and medium hospitals precisely because consolidation leaves those hospitals with fewer alternatives.

Layer 3: The fragmented market — Direct contracts, 340B, specialty pharmacy

Despite the GPO consolidation, the channel is fracturing.

Direct contracts. Large hospital systems and health networks increasingly negotiate directly with manufacturers, bypassing GPOs entirely. They have enough scale to demand better pricing. Smaller hospitals cannot do this and rely on GPO contracts.

340B program. Covered entities (qualifying hospitals, clinics, and safety-net providers) can buy drugs at steep discounts — often 20-50% below wholesale acquisition cost — because federal law requires manufacturers to offer these discounts to organizations serving vulnerable populations. Hospitals can resell 340B drugs to outpatients, pocketing the savings. This creates a secondary market and price pressure.

Specialty pharmacy. Drugs requiring cold chain, frequent monitoring, or complex administration (biologics, oncology, cell therapies) increasingly flow through specialty pharmacies rather than hospital formularies. These are often owned by PBMs, insurers, or wholesalers and operate outside traditional hospital procurement.

The result is a fragmented supply chain where the same drug reaches different hospitals at different net prices depending on whether it flows through a GPO contract, a direct manufacturer deal, a 340B program, or a specialty pharmacy.

How hospital formulary decisions actually get made

A hospital pharmacy and therapeutics (P&T) committee makes formulary decisions — which drugs to stock, which to limit, which to exclude. The committee typically includes doctors, nurses, pharmacists, and often an administrator focused on cost.

But the committee operates within constraints set by others:

GPO contracts determine which drugs are available at negotiated prices. If a drug is not on the GPO’s contract, the hospital can still buy it, but at retail or negotiated-directly prices, which are usually higher. This creates pressure to choose GPO-contracted drugs.

Rebate contracts with manufacturers (negotiated through the GPO or directly) mean that a higher-priced drug might actually net cheaper after rebates than a lower-priced competitor. The hospital does not see the rebate mechanics — only list price and (if transparent enough) aggregate rebate volume. This makes true cost comparison difficult.

Prior authorization requirements from insurers mean that even if a drug is on the formulary, patients may not get it. The insurer’s formulary (often managed by a PBM) overlays the hospital’s formulary.

The result: hospital formulary decisions are constrained more by wholesale pricing mechanics and rebate structures than by clinical efficacy alone.

The incentive misalignment

GPOs, wholesalers, PBMs, and specialty pharmacies all have financial incentives that do not always align with the hospital’s goal of lowest total cost. A GPO earns a fee when a drug gets a contract slot. A wholesaler makes slightly better margin on higher-priced generics or specialty drugs. A PBM gets a rebate from manufacturers that may or may not flow back to the employer/patient. A specialty pharmacy earns money from volume and complexity.

This misalignment is structural and persistent. Hospitals have fought it for decades — through GPO accountability measures, rebate pass-through agreements, and direct contracting. But the fragmentation of the supply chain means no single buyer has enough leverage to enforce true alignment across all players.

What this means for procurement

Understand your actual net cost, not list price. Hospital formularies are built on list prices and aggregate rebate percentages, but individual drugs’ net costs are often opaque. Demand item-level transparency from your GPO and wholesalers, or negotiate directly when scale permits.

Recognize GPO limits. GPOs deliver real savings through volume, but the fee-for-contract model means your GPO is not necessarily steering you to the lowest-cost option. Periodically audit whether GPO-contracted drugs are actually cheaper than direct-negotiated alternatives.

Use 340B strategically if eligible. If you are a qualifying covered entity, 340B purchasing is often the lowest-cost sourcing channel. But it creates secondary-market complications and inventory management costs. Make sure the savings justify the administrative burden.

Build specialty expertise internally. Specialty pharmacy is growing faster than traditional hospital pharmacy, and margins are higher. You cannot rely on traditional sourcing for biologics and cell therapies. You need cold-chain infrastructure and dedicated purchasing strategy.

Frequently asked questions

Why can’t a hospital just buy directly from manufacturers?

They can, but direct contracts require scale. A hospital with 300 beds has less leverage than a health system with 5,000 beds spread across states. Small hospitals are better served through GPOs. Large systems often use both: GPO contracts for commodity drugs, direct contracts for specialty or high-volume products.

Do wholesalers actually add value?

Yes, but in ways often invisible to hospital procurement. Wholesalers operate massive logistics networks, manage inventory risk, handle returns, ensure regulatory compliance, and solve supply problems in real time. You would not want to coordinate directly with 200+ manufacturers. But the margin they take is increasingly under pressure.

What is the difference between a GPO contract and a rebate?

A GPO contract sets the price at which a hospital buys from a wholesaler. A rebate is a payment from the manufacturer to the GPO or hospital, usually based on volume or market share achieved. Rebates are retrospective and confidential. A drug might have a list price of $100, a GPO contract price of $80, and a rebate that brings the net cost to $60 — but the hospital only sees the $80.

Why do some drugs stay expensive even after biosimilars enter?

Biosimilars are only 25-35% cheaper than the reference product. They are not generic-level discounts. And biosimilars do not automatically displace reference products because switching requires physician and patient consent. If a hospital’s formulary still prefers the reference product, the reference product stays expensive.

Sources

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