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Glossary / Formulary

Formulary

Definition

A formulary is the list of medications a health plan covers, organized into cost tiers and managed by its PBM — the document that decides what a prescription costs an insured patient at the counter.

By Lithos Staff · Updated July 2026

At a glance
  • The covered-drug list of a plan, managed by its PBM
  • Tiered copays; rebates influence placement
  • Utilization management attaches to expensive tiers
  • DTC programs run their own treatment-catalog “formulary”

How formularies work

Drugs are placed in tiers — generics low, preferred brands middle, specialty high — with copays rising by tier. Placement is negotiated: manufacturers pay rebates for favorable positions, and PBMs attach utilization management (prior authorization, step therapy, quantity limits) to expensive entries. Exclusion lists name drugs not covered at all, and formulary decisions on GLP-1s have repeatedly made national news for exactly this reason.

Payer / plan sponsorfunds the benefitDrug manufacturerpays rebates for placementPBMformulary · rebates · claimsPharmacy networkdispenses · copaycash-pay prescriptions skip the hub entirely — pharmacy fills at a direct price
The PBM sits at the center of the drug benefit: payers fund it, manufacturers pay rebates into it, pharmacies dispense through it. Cash-pay routes around the whole hub.

Formularies and cash-pay programs

A different sense of the word matters in DTC: the program formulary — the treatment catalog a telehealth service offers and its clinicians may prescribe from. Building it means choosing medications, dose forms, and pharmacy sources (retail, mail, compounded) that clinicians can match to patients. Insurance formularies answer what is covered; program formularies answer what we offer — a distinction worth keeping crisp in team vocabulary.

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Lithos runs the clinicians, pharmacies, and 50-state rules behind your care program — one API.

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Frequently asked questions

Who decides what is on a formulary?

The PBM’s pharmacy and therapeutics committee, shaped by clinical evidence and manufacturer rebate negotiations.

Why was my patient’s drug not covered?

It may be excluded, in a high tier, or gated behind prior authorization or step therapy — the formulary entry tells you which.

What is a formulary in a DTC program?

The internal catalog of treatments clinicians may prescribe — the program’s clinical menu, distinct from any insurance list.

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