Limited Distribution Networks Explained: How LDNs Work

What a limited distribution network is, why manufacturers restrict specialty drugs to a handful of pharmacies, how network sizes break down in practice, and what the model means for access and data.

Published July 21, 2026

Specialty Pharmacy

A limited distribution network (LDN) is a channel strategy in which a pharmaceutical manufacturer contracts with a small, hand-picked set of specialty pharmacies — sometimes just one — to dispense a specific drug, instead of making it available through open wholesale channels. Manufacturers use LDNs for high-cost specialty therapies that serve small patient populations, carry strict handling or safety-monitoring requirements, or demand intensive patient support. In exchange for exclusivity, the contracted pharmacies commit to defined service levels, clinical protocols, and detailed data reporting back to the manufacturer. IPD Analytics defines a limited distribution drug (LDD) as one restricted to 24 or fewer specialty pharmacies, and notes that roughly 80% of LDDs are dispensed by fewer than 10.

How an LDN differs from open distribution

In traditional retail distribution, a manufacturer sells to wholesalers, who resell to essentially any licensed pharmacy. The manufacturer has little visibility into who dispenses the product or how patients fare on it.

In a limited distribution model, the manufacturer signs direct agreements with specific specialty pharmacies (and often a third-party logistics provider). Only those pharmacies can obtain the drug. Prescriptions written anywhere in the country are routed — usually via the manufacturer’s hub or the prescriber’s office — to a network pharmacy, which handles benefit verification, prior authorization support, financial assistance, dispensing, and adherence follow-up.

Why manufacturers limit distribution

Several motivations recur across LDN programs:

Safety and REMS compliance. Drugs subject to a Risk Evaluation and Mitigation Strategy (REMS) may require certified pharmacies, prescriber training, or patient monitoring. A small network is far easier to certify and audit than thousands of retail locations.
Special handling. Cold-chain biologics, short-stability products, and cell and gene therapies need storage, packaging, and logistics capabilities most pharmacies do not have.
Small patient populations. For a rare-disease therapy with a few hundred patients nationwide, broad distribution creates inventory waste and dilutes clinical expertise. Concentrating volume in one or two pharmacies keeps every pharmacist on the team familiar with the therapy.
Data visibility. Network contracts typically require dispensing status, time-to-fill, adherence, and discontinuation reporting. That data feed is often the manufacturer’s best real-world view of its own launch.
Channel economics. Onboarding, credentialing, and managing each additional network pharmacy carries real cost, so manufacturers add pharmacies only when capacity or payer access requires it.

What actual network sizes look like

Drug Channels Institute’s 2025 analysis of 382 specialty drugs with manufacturer-defined limited or exclusive networks found that genuinely narrow networks are the norm, not the exception:

Network size	Share of limited-network drugs
Exclusive (1 pharmacy)	34%
2–4 pharmacies	34%
5–10 pharmacies (avg. 7)	20%
11–25 pharmacies (avg. 15)	12%

The same analysis highlights a split in who wins which networks. Pharmacies affiliated with the largest PBMs have access to about half of the specialty drugs in limited (multi-pharmacy) networks, but only about one-quarter of exclusive-network products. Independent specialty pharmacies do disproportionately well in exclusive arrangements — Drug Channels found Biologics by McKesson in 14% and PANTHERx Rare in 12% of exclusive-network drugs.

Who participates in LDNs

Several distinct pharmacy types compete for LDN contracts:

PBM-affiliated specialty pharmacies — Accredo Specialty Pharmacy, CVS Specialty, and Optum Specialty Pharmacy — bring national scale and payer alignment; per Drug Channels, the three largest specialty pharmacies accounted for about two-thirds of pharmacy-dispensed specialty revenue in 2025.
Large retail-affiliated and distributor-owned players such as Walgreens Specialty Pharmacy and US Bioservices combine reach with limited-distribution programs.
Independent and rare-disease specialists — including Amber Specialty Pharmacy, AnovoRx, Onco360, Orsini Specialty Pharmacy, PANTHERx Rare, and Senderra Specialty Pharmacy — compete on high-touch service, therapy-area depth, and flexible data sharing.
Health-system specialty pharmacies, often built with enablers like Shields Health Solutions or Clearway Health, have grown quickly — Drug Channels counts 553 accredited health-system specialty pharmacy locations in 2025, up from 106 in 2017 — and increasingly seek access to limited networks for their own patients.

How pharmacies are selected

Manufacturers typically evaluate candidates on a consistent set of criteria, summarized well in Frier Levitt’s guidance for pharmacies seeking network access:

Clinical expertise in the therapy area, including nursing and pharmacist support models.
Accreditation from bodies such as URAC or ACHC — held by more than 1,900 U.S. dispensing locations as of 2025.
Speed — fast benefits investigation and short time-to-first-fill are often the deciding metrics.
Data capabilities — secure, near-real-time reporting on dispenses, adherence, inventory, and adverse events.
Payer and PBM relationships, since a pharmacy that is out-of-network for major plans creates access friction.
Patient support infrastructure — financial assistance navigation, refill outreach, and side-effect counseling.

Trade-offs and criticisms

LDNs are not free of controversy. When a patient’s insurance steers them to a PBM-owned pharmacy that is not in the drug’s network — or vice versa — the result can be delays, transfers, and abandonment risk. Payers complain about losing dispensing control and visibility; pharmacies excluded from networks argue the model entrenches incumbents. Researchers writing in the American Journal of Managed Care have also documented how restricted distribution can be used to impede generic and biosimilar developers’ access to reference samples, which drew regulatory attention in the CREATES Act era. Manufacturers designing networks should treat these frictions as real costs of the model, not just competitor complaints.

Practical takeaways

For a manufacturer planning a specialty launch, the LDN decision reduces to a few questions: Does the product carry REMS, handling, or monitoring requirements that only certified pharmacies can meet? Is the patient population small enough that concentrated expertise beats broad access? What data do you need back, and will network partners contractually commit to it? Start from the patient journey and payer mix rather than from a target pharmacy count — DCI’s data shows successful networks range from a single exclusive partner to 25 pharmacies. Revisit network composition annually: payer dynamics, health-system pharmacy growth, and your own volume will shift the right answer over the product lifecycle. Comparing candidate pharmacies side by side on turnaround times, data commitments, and therapy-area references — not just size — is the most reliable way to build a network that works.