Rezdiffra (Resmetirom) Storage, Stability & Shelf Life

Rezdiffra is the brand name for resmetirom, an oral thyroid hormone receptor beta (THR-β) agonist tablet approved by the FDA in March 2024 for adults with noncirrhotic MASH (metabolic dysfunction-associated steatohepatitis, previously called NASH) with moderate to advanced liver fibrosis (F2-F3), used alongside diet and exercise. It comes as 60 mg, 80 mg, and 100 mg film-coated tablets manufactured by Madrigal Pharmaceuticals. This article is about physical storage and stability, not dosing decisions, which should be set by the prescriber.

The routine storage question has a simple, label-based answer. The harder and more common real-world question is what to do with a specific bottle after an undocumented heat, cold, or humidity exposure, and the label does not fully answer that. This page treats those as two separate questions.

Rezdiffra (resmetirom) tablets are labeled for storage at controlled room temperature, 20°C to 25°C (68°F to 77°F), with permitted excursions between 15°C and 30°C (59°F to 86°F), in the original container with the desiccant in place. Storage and handling instructions come from the FDA-approved prescribing information for Rezdiffra (NDA 217785, revised 2024). The label does not publish a specific shelf-life duration on a public-facing page in a way this article can independently confirm; the expiration date printed on each bottle is the authoritative figure for any given lot, and any specific "X months" claim should be verified against that printed date or against the current label before being repeated to a patient.

What the label actually establishes

• Temperature range: 20°C to 25°C is the target range, with brief excursions down to 15°C and up to 30°C allowed. This is a standard "controlled room temperature" designation used across many oral solid medications, not something unique to resmetirom.
• Container: tablets are dispensed in a container with a desiccant. Removing the desiccant or leaving the bottle open reduces the moisture protection the container was designed to provide.
• Light: the label does not describe a specific light-protection requirement beyond normal dispensing practice.

Everything past this point, especially what happens to potency after a specific excursion outside 15-30°C, is not spelled out in consumer-facing label language. Manufacturers generate accelerated and long-term stability data internally to support the approved shelf life, but the detailed stability dataset is not something a patient, caregiver, or this article can access or verify. Where this article discusses excursion risk below, it is describing general pharmaceutical stability principles, not resmetirom-specific data, and that boundary should be stated to the reader rather than blurred.

The compact answer, for reference

Store Rezdiffra tablets at 68°F to 77°F in the original bottle with the desiccant, avoid refrigeration or freezing, and do not rely on tablets that have been left in a hot car, a mailbox during a heat wave, or an open humid environment for an extended period without checking with a pharmacist first. If a bottle sat outside the 15-30°C range for a brief period (hours, not days), general pharmaceutical stability practice treats this as low risk for most solid oral tablets, but this is a general principle, not a resmetirom-specific finding, and a pharmacist or the manufacturer can confirm handling for a specific lot.

Shelf life and expiration dating

The expiration date printed on the bottle is the number that matters for any individual patient, because it reflects the specific lot's manufacture date and the approved stability period for that formulation. Once a bottle is opened, nothing in the publicly available label indicates a shortened "use within X days" restriction, provided the desiccant stays in the bottle and the cap is closed after each use.

If a pharmacy repackages tablets into blister cards or a compliance packaging system for a patient, the repackaged product may carry a different, often shorter, beyond-use date than the manufacturer's original expiration date, because the new packaging may not offer the same moisture protection as the original bottle and desiccant. Patients switching to compliance packaging should ask the dispensing pharmacist what beyond-use date applies, rather than assuming the original bottle's expiration date carries over.

What a temperature or moisture excursion means in practice

There is no published resmetirom-specific data in this article's source material describing exactly how much potency is lost after a defined excursion (for example, 6 hours at 35°C, or three days at 90% humidity). In the absence of that data, the practical guidance below reflects general pharmaceutical handling principles for oral solid tablets, and it should be read as caution, not as a tested threshold for resmetirom specifically.

• Tablets that are visibly discolored, chipped, unusually soft or sticky, or have an odd odor should not be taken, regardless of how the excursion happened.
• A short exposure to heat above 30°C, such as a few hours in a warm car or a delayed mail delivery in summer, is unlikely by general principle to be visually detectable and is the kind of situation where calling the dispensing pharmacist for guidance is more useful than guessing.
• Sustained exposure to high heat (well above 30°C for days) or to freezing temperatures, or a bottle that has visibly absorbed moisture, is a reasonable trigger to ask the pharmacy to replace the medication rather than take a chance on reduced effectiveness of a drug being used to treat liver fibrosis.
• Freezing is not addressed in the label because normal home storage does not involve freezing. If a shipment was left in freezing conditions, warming the sealed bottle to room temperature before opening reduces the chance of condensation forming inside the container when it is opened.

Practical handling

• Keep tablets in the original bottle with the desiccant. Long-term storage in weekly pill organizers removes that moisture protection; a short-term organizer (days, not weeks) is a smaller compromise than months of open-air storage, but the label does not certify any specific organizer duration.
• Do not store in the refrigerator or bathroom medicine cabinet, both of which introduce humidity swings that work against the desiccant's purpose.
• Patients receiving Rezdiffra by mail order in extreme summer or winter weather can ask the specialty pharmacy whether temperature-monitored or expedited shipping is available; whether this is offered, and at what cost, varies by pharmacy benefit and is not something this article can state as universal.
• Tablets are immediate-release and not enteric-coated, so the FDA label does not include a "do not cut or crush" instruction, but individualized decisions about splitting tablets or altering the route of administration (for example, crushing for a feeding tube) should come from the prescriber or pharmacist, not from general labeling language, because bioavailability with altered administration has not been established here.

Evidence boundary: what is established, what is not

Established, from the FDA label: the 20-25°C target range, the 15-30°C excursion allowance, the desiccant-containing HDPE bottle as the dispensed container, and the absence of a specific light-protection requirement.

Plausible but not established in the material available here: the exact degree of potency loss after a defined time-temperature excursion outside the labeled range, and any manufacturer-specific accelerated stability dataset. General ICH-style stability testing frameworks exist for new drug approvals, but this article does not have resmetirom-specific accelerated stability numbers that could be stated as fact.

Not established, and removed from this draft pending verification: a specific molecular selectivity ratio for THR-β over THR-α, exact percentage figures for LDL, ALT, TSH, or gallbladder event rates from the pivotal trial, and any wholesale price figure. These numbers appear in public discussion of the drug's approval, but this draft cannot attach them to a verifiable primary citation and will not present them as settled facts. An editor with direct access to the current FDA label and the published trial report should confirm and restore any of these figures with a correct citation before publication.

Two attributed quotations describing the drug's mechanism and trial significance also appeared in an earlier version of this material. Neither could be verified against a checkable source, so both have been removed rather than repeated as if sourced.

Storage-breach decision framework

Use this to decide what to do with a specific bottle of Rezdiffra, rather than the medication in general.

This table is a general decision aid built from labeled storage boundaries and standard pharmaceutical handling practice. It is not a substitute for pharmacist or prescriber judgment on a specific bottle, and it does not establish a tested potency-loss threshold for resmetirom.

When to involve a pharmacist or prescriber urgently

Contact the prescribing clinician or pharmacist, rather than continuing on a possibly compromised supply, if any of the following apply: the medication was exposed to conditions clearly outside the labeled range for an extended period, the tablets show visible signs of degradation, a patient with MASH and fibrosis has new or worsening symptoms (worsening fatigue, jaundice, abdominal swelling, or right upper quadrant pain) that might reflect either disease progression or reduced drug effectiveness, or there is uncertainty about whether a recent dose came from a compromised bottle. None of these situations should be resolved by guessing based on general storage advice alone.

This article covers storage and handling only. It is not medical advice and does not provide individualized dosing guidance. Dosing, monitoring, and management of MASH should be directed by the prescribing clinician. This draft is pending qualified medical review; specific figures marked as unverified above should be confirmed against the current FDA label and primary trial publication before this page is published.