in pictures and a few words
What it is and why it matters
Resmetirom is a tablet for adults with fatty liver disease when the liver already has inflammation and moderate or advanced scarring. It is the first approved medicine for this disease.
- Approved in the US in March 2024 — before that there was no treatment at all
- It is taken in addition to diet and exercise, not instead of them
- In essence, it’s a thyroid hormone left with only its action on the liver
What happens to the liver
Fatty liver disease is the most common liver disease in the world. Fat in the liver on its own rarely leads to serious consequences.
- In some people, inflammation and cell damage join the fat
- In response, the liver starts to scar
- The more scarring, the higher the risk of cirrhosis and complications
A hormone that works in the liver
Thyroid hormones make cells burn fat, including in the liver. But too much of them speeds up the heart, disrupts its rhythm and leaches calcium from the bones.
- These hormones have two kinds of “locks”: one mostly in the liver, the other in the heart and bones
- Resmetirom opens the liver lock and goes mainly to the liver
- The liver burns stored fat, while the heart and bones barely receive the command
What the study showed
In a large study, a small piece of liver was examined under a microscope before and after treatment. With resmetirom, inflammation cleared and scarring decreased more often than with a dummy pill.
- This is a change in the liver tissue itself, not just in blood tests or a scan
- Scarring decreased by at least one stage
- The first medicine to improve both inflammation and scarring this way in a rigorous study
Tested in people. Tested in people: a large study in adults with liver inflammation and scarring, together with diet and exercise.
Who it’s for
Adults whose liver has inflammation and already moderate or advanced scarring.
- First they find out how much scarring the liver has — without this the medicine isn’t prescribed
- This is measured with a device that gauges liver stiffness, by blood tests or a small piece of liver
- “Fat on ultrasound” on its own is not a reason for this medicine
How to take it
Once a day, with or without food — it doesn’t matter. The dose depends on body weight.
- Weight under 100 kg — 80 mg a day
- Weight 100 kg or more — 100 mg a day
What can happen and what is checked
Diarrhea and nausea are most common at the start of treatment. They usually pass.
- Liver tests are done before starting and then on your doctor’s schedule
- If liver tests rise markedly, the medicine is stopped
Important. Taking cholesterol medicines — statins? Tell your doctor in advance: resmetirom changes how they work, and the dose is reviewed.
Not instead of weight loss
Losing weight remains the best-proven way to help the liver: it reduces both inflammation and scarring.
- The best-proven step is to lose 7–10 kg for every 100 kg of body weight
- The medicine is added to diet and exercise, not used instead of them
- The cause is addressed too: weight, insulin sensitivity, cholesterol, blood pressure
Who should see a doctor first
The medicine isn’t for everyone with a liver problem. Discuss it with your doctor first.
- Cirrhosis — the medicine hasn’t been studied in it and isn’t prescribed
- Hepatitis, liver damage from medicines or alcohol — it isn’t indicated here
- You take medicines regularly — resmetirom doesn’t combine with some of them
Important. It isn’t a general “liver” remedy: only for this disease, when inflammation and moderate or advanced scarring have been confirmed.
In one sentence
Resmetirom is the first medicine for fatty liver disease with scarring. With it, inflammation cleared and scarring decreased more often than with a dummy pill, but it is taken together with weight loss, not instead of it.
In brief
Why this is an event
Fatty liver disease is the most common liver condition in the world. For a long time the patient pathway looked like this: ultrasound finds a "fatty liver", the advice is to lose weight, and medicine stops there. Meanwhile a proportion of those patients progress to steatohepatitis — inflammation with cell injury — and from there to fibrosis and cirrhosis.
Attempts to create a drug ran for twenty years and kept failing in phase 3. Resmetirom was the first to reach approval.
Mechanism: a hormone that works only in the liver
Thyroid hormones make cells burn fat faster, the liver included. Treating the liver with them is impossible: excess hormone races the heart, causes arrhythmia and leaches calcium from bone.
The solution lay in receptor biology. Thyroid hormone receptors come in two types:
| Receptor type | Where it dominates | What activation produces |
|---|---|---|
| THR-α | Heart, bone | Tachycardia, arrhythmia, bone loss |
| THR-β | Liver | Accelerated fat metabolism in the liver cell |
Resmetirom selectively activates the beta type and is additionally taken up preferentially by the liver. The result is a hormonal effect delivered to an address: the liver burns its stored fat while heart and bone barely receive the message.
What the trial showed
▸MAESTRO-NASH (NEJM, 2024; n=966) — a phase 3 trial with liver biopsy before and after treatment. Resmetirom significantly more often than placebo produced resolution of steatohepatitis and fibrosis improvement of at least one stage [1].
The value lies in the biopsy: this is not an improvement in blood tests or less fat on a scan, but a change in the tissue itself — inflammation clearing and scar regressing. No drug before it had shown improvement on both endpoints simultaneously in a randomised trial [2].
Who it is for
▸adults with MASH (metabolic dysfunction-associated steatohepatitis); ▸with fibrosis stage F2 or F3 — moderate or advanced; ▸in addition to diet and physical activity.
Not indicated: in cirrhosis (F4), in simple steatosis without inflammation and fibrosis, or where the fibrosis stage has not been established.
Dosing and monitoring
| Body weight | Dose |
|---|---|
| Below 100 kg | 80 mg daily |
| 100 kg and above | 100 mg daily |
Taken orally once daily, with or without food.
What to monitor:
▸liver enzymes — before starting and then on the clinician's schedule; the drug is stopped if they rise significantly; ▸tolerance in the first weeks: diarrhoea and nausea are the commonest complaints, usually transient; ▸the statin regimen — resmetirom alters statin metabolism, so the dose is reviewed in advance; ▸concomitant drugs — there are significant interactions through hepatic enzymes.
What it does not do
▸It does not replace weight loss. A 7–10% reduction remains the best-evidenced intervention; the drug is added to it. ▸It does not treat cirrhosis. At F4 it has not been studied. ▸It is not a general "liver drug" — there is no indication in hepatitis, drug-induced liver injury or alcohol-related liver disease. ▸It does not cancel work on the cause: insulin resistance, obesity, dyslipidaemia, blood pressure.
Summary
▸The first approved medicine for steatohepatitis with fibrosis — before 2024 there were none. ▸The mechanism is elegant: a thyroid hormone redirected to act only through the hepatic beta receptor. ▸The evidence is strong: biopsy before and after, two histological endpoints, 966 patients. ▸The indication is narrow: MASH with F2–F3 fibrosis, not cirrhosis and not simple steatosis. ▸Weight-based dosing, liver enzyme monitoring, attention to statins. ▸Alongside lifestyle change, not instead of it.
Indications can be discussed at a consultation; the product can be ordered here.
References
1. Harrison SA, et al. A phase 3, randomized, controlled trial of resmetirom in NASH with liver fibrosis (MAESTRO-NASH). N Engl J Med. 2024;390(6):497–509. PMID 38324483
2. Mironova M, et al. In NASH with liver fibrosis, resmetirom improved NASH resolution and reduced fibrosis at 1 year. Ann Intern Med. 2024. PMID 38830210
3. REZDIFFRA (resmetirom) US Prescribing Information, Madrigal Pharmaceuticals.
Key facts
- Resmetirom (brand name Rezdiffra, Madrigal Pharmaceuticals) is the first drug ever approved for metabolic dysfunction-associated steatohepatitis (MASH, formerly NASH) with liver fibrosis. FDA approval came on 14 March 2024.
- Mechanism: a selective agonist of the beta thyroid hormone receptor (THR-β). The liver is dominated by the beta receptor, while heart and bone carry the alpha type. The drug therefore accelerates fat metabolism inside the liver cell without the tachycardia, arrhythmia and bone loss that excess thyroid hormone produces.
- Indication: MASH with moderate to advanced fibrosis (stages F2–F3) in adults, in addition to diet and exercise. It is not indicated in cirrhosis (F4).
- MAESTRO-NASH (NEJM, 2024): in a phase 3 trial with liver biopsy in 966 patients, resmetirom achieved both resolution of steatohepatitis and fibrosis improvement of at least one stage significantly more often than placebo.
- This is the first medicine to demonstrate improvement on both key histological endpoints — inflammation and fibrosis — in a randomised biopsy-controlled trial.
- Dosing is by body weight: 80 mg daily below 100 kg and 100 mg daily at 100 kg or above. Taken orally once a day, with or without food.
- The fibrosis stage must be established before prescribing — by biopsy or non-invasively (elastography, calculated indices). "Fat on ultrasound" is not by itself an indication.
- Common adverse events are diarrhoea and nausea, usually early in treatment. Liver enzymes are monitored, and the drug is stopped if they rise significantly.
- Interactions matter: the drug alters statin metabolism, so the statin dose is reviewed in advance, and it is incompatible with several strong hepatic enzyme inhibitors and inducers.
- Resmetirom does not replace weight loss and metabolic risk correction — it is prescribed in addition to them, not instead.
