Express Scripts and Optum Rx set 2026 tirzepatide coverage, leaving Zepbound vials off their lists

Express Scripts and Optum Rx, two of the largest pharmacy benefit managers in the United States, have set their 2026 coverage rules for tirzepatide, the drug sold as Mounjaro and Zepbound. Both list the Zepbound auto-injector pen as covered, and both leave the Zepbound vial off their covered lists ^[2][3].

Express Scripts' 2026 National Preferred Formulary takes effect January 1, 2026 and runs through December 31, 2026 ^[1]. It lists Mounjaro [INJ] as a covered product, along with Ozempic [INJ], Ozempic Tablets, Rybelsus, Foundayo and liraglutide [INJ] ^[1]. The Zepbound pen is covered, while the Zepbound vial appears on the companion exclusion list, which names drugs that are not covered on this formulary ^[2]. Express Scripts notes that brand-name drugs may move to nonformulary status if a generic equivalent becomes available during the plan year, and that the drug list is not all-inclusive and does not guarantee coverage ^[1].

Optum Rx's 2026 Premium Formulary, also effective January 1, 2026, puts the Zepbound auto-injector at Tier 2 with prior authorization and assigns the Zepbound solution, the vial form, to Tier E, its excluded tier ^[3]. Mounjaro is covered with prior authorization ^[3].

Optum Rx defines Tier 2 as "mid-range cost preferred brand name," and Tier E as excluded, where a medication "may not be covered or need prior authorization" ^[3]. The plan's prior authorization note means the prescriber must give Optum Rx more information before coverage is decided ^[3].

Express Scripts tells members using an excluded medication to ask their physician about switching to a preferred alternative, and says a physician can request a coverage review through the plan's online portal if there is a clinical reason to continue the current drug ^[2].

Neither company disclosed 2026 copays or out-of-pocket dollar amounts for these products, and neither said how many employer or health plans use these specific formularies. Both state that where a formulary differs from an individual benefit plan, the benefit plan documents govern ^[1][3].

Why it matters for patients

The two lists treat the same molecule differently depending on how it is packaged. A person with a Zepbound prescription written for the pen is on covered ground at both companies, though Optum Rx requires prior authorization first ^[3]. A person using the Zepbound vial is on an excluded product at both, which typically means the prescription is not paid for under the pharmacy benefit unless a coverage review succeeds ^[2][3].

For Mounjaro, both formularies keep coverage in place but attach prior authorization, so a prescriber must document the case before the plan pays ^[3]. Express Scripts also covers several other GLP-1 products, including Ozempic, Rybelsus, Foundayo and liraglutide, on its 2026 preferred list ^[1].

Coverage rules are set by the plan, not by the drugmaker, so two people taking the same medication can face different answers. Express Scripts states plainly that its list does not guarantee coverage and that plan materials control ^[1]. Optum Rx says its tiers set cost levels that are assigned by the employer or plan sponsor, not by Optum Rx ^[3].

What happens next

Both formularies took effect January 1, 2026 ^[1][3]. The Express Scripts list is scheduled to run through December 31, 2026 and is subject to change during the year ^[1]. Optum Rx states that medications may move to a higher tier or be excluded on January 1 or July 1 of each year ^[3]. Whether either company adds the Zepbound vial later in 2026 has not been reported.