No se trata de una red nacional (de farmacias), sino de listas de medicamentos nacionales o listas nacionales de medicamentos; que entiendo que se trata de una categoría de medicamentos; otras categorías son:

"Preferred Drug Lists"
"National Direct Drug Lists"
"Select Drug Lists"
"Traditional Open Drug Lists"
"PreventiveRx Drug Lists"
"Exclusive Specialty Drug List"
etc
Referencia: https://www.anthem.com/ca/ms/pharmacyinformation/home.html

"Network" se refiere a una red de farmacias o similar, como puede verse en la misma página.


"Formulary" se refiere a listas de medicamentos o drogas.

Una referencia de este significado:

"Formulary/Drug Lists
Which formulary/drug list applies to your plan? If you have
coverage through your work, you can ask your employer
directly.

Formulary/Drug Lists
All of the drug lists in this section include our Drug Search (Searchable) Tool functionality"
https://www.anthem.com/ca/ms/pharmacyinformation/home.html

Pueden verse muchos ejemplos de uso de "formulary" en el mismo sentido en https://www.linguee.com/english-spanish/search?source=auto&q...

En los listados en español, Anthem.com traduce como "lista de medicamentos" a las "drug list".
Por ejemplo: "Individual 2021 Select Drug List (Searchable) | (PDF)" en
https://www.anthem.com/ca/ms/pharmacyinformation/home.html
abre un PDF con:
"Lista de medicamentos selectos de California 2021
Puedes buscar el nombre del medicamento para conocer la información actualizada, ..."

National Formulary: Full name: United States Pharmacopeia and National Formulary (USP-NF). An official publication, issued first by the American Pharmaceutical Association and now yearly by the United States Pharmacopeial Convention, that gives the composition, description, method of preparation, and dosage for drugs.

The National Formulary (NF), established in 1888 by the American Pharmaceutical Association, includes standards for excipients, botanicals, and other similar products.
https://www.medicinenet.com/national_formulary/definition.ht...

At its most basic level, a formulary is a list of medicines. Traditionally, a formulary contained a collection of formulas for the compounding and testing of medication (a resource closer to what would be referred to as a pharmacopoeia today). Today, the main function of a prescription formulary is to specify particular medications that are approved to be prescribed at a particular hospital, in a particular health system, or under a particular health insurance policy.

In the US, where a system of quasi-private healthcare is in place, a formulary is a list of prescription drugs available to enrollees...
https://en.wikipedia.org/wiki/Formulary_(pharmacy)

What Is a Formulary?
A drug formulary, or preferred drug list, is a continually updated list of medications and related products supported by current evidence-based medicine, judgment of physicians, pharmacists and other experts in the diagnosis and treatment of disease and preservation of health. The primary purpose of the formulary is to encourage the use of safe, effective and most affordable medications.
https://amcp.org/sites/default/files/2019-03/Formulary Manag...

Formularies are lists of medications available to enrollees, and tiered formularies provide financial incentives for patients to select lower-cost drugs on the list. When used appropriately, formularies can help to manage drug costs without negatively impacting enrollees' health.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1403290/

National Direct Drug List
This list may be for you if your health insurance plan is through an employer.
https://www.ingenio-rx.com/drug-lists-pharmacy-tools/

Formulary: Prescripción.
https://www.thesaurus.com/browse/formulary

Network: Sistema, Organización, Estructura.
https://www.thesaurus.com/browse/network

Lo Nacional no son los medicamentos directos, es el Sistema. (y lo directo se refiere a un plan específico, hay Essential, National, National Direct y Traditional Open).