Litfulo (Ritlecitinib Tosylate) 50 mg Capsules: Uses, Dose, MOA, Side effects

Litfulo (Ritlecitinib) is a JAK-STAT inhibitor, a kinase-blocking drug that irreversibly inhibits the ATP binding sites. It was approved by the FDA on 23rd June 2023 for the following indications:

  • ✔️ Severe alopecia areata in children older than 12 years of age and adults.

  • ❌ It is not indicated for use in combination with other immuno-modulatory drugs like cyclosporin, other JAK inhibitors, and other strong immunosuppressant drugs.

Litfulo (Ritlecitinib) Dose:

The usual recommended dose is 50 mg once daily with or without food. The capsules should be taken as a whole without breaking them or crushing them. The dose should be taken daily at the scheduled time, however, in case the dose is missed, it should be taken immediately unless the time for the next scheduled dose is less than 8 hours.

Avoid Litfulo (Ritlecitinib) in advanced liver disease. In addition, the treatment may be discontinued if the platelet counts drop to less than 50,000/ul or the lymphocyte count drops to less than 500 cells/ul.

If there is treatment interruption due to any reason and the duration is less than 6 weeks, it usually does not result in hair loss in the regenerated area.

Considerations before Litfulo (Ritlecitinib) Treatment Initiation:

  • Get vaccinated as per the CDC schedule.

  • Get tested for latent or active pulmonary tuberculosis. If tests for latent TB are positive, get the recommended treatment before starting Litfulo (Ritlecitinib).

  • Check hepatitis B and C status. Do not start if there is an active infection.

  • Check hematological parameters. Avoid Litfulo treatment if the platelet counts are less than 100,000/ul and the absolute lymphocyte counts are less than 500/ul.

Use in specific populations:

  • Pregnancy and lactation:

Avoid as data are insufficient

  • Old age (>65 years):

No dose adjustment is needed

  • Liver disease:

No dose adjustment is required in mild to moderate hepatic dysfunction. Avoid in severe and advanced liver disease.

Litfulo (Ritlecitinib) Contraindications and Warnings:

Avoid its use in individuals who are allergic to it. Allergic reactions have been reported in clinical trials.

  • Infections:

Serious infections can occur. The most commonly reported serious infections include:

  • Covid pneumonia

  • Appendicitis

  • Sepsis

  • Opportunistic infections including herpes zoster in multiple dermatomes.

Avoid using Litfulo (Ritlecitinib) in patients who have resided in TB-endemic areas and who are prone to develop systemic fungal infections. In case, the person catches an infection, it should be immediately treated and all immunosuppressants should be stopped. Once the infection resolves, Litfulo (Ritlecitinib) treatment may be restarted.

Similarly, anti-TB drugs should be given to all patients who have active or latent TB. Once the course of TB treatment is completed, then the patient may be considered for Litfulo therapy with close observation (for disease reactivation).

The same goes for viral infections like herpes zoster and hepatitis. Once the treatment for viral infection is over, only then can the person be enrolled for Litfulo (Ritlecitinib) treatment.

  • Risk of Cancers:

Skin cancer (Melanoma) and non-melanoma skin cancers have been observed in clinical trials. Other cancers in the post-marketing reports include lymphoma, lung cancer, and cervical cancer.

  • Cardiac events:

Litfulo has been associated with an increased risk of cardiovascular events including stroke, myocardial infarction, angina, and heart failure. Compared to TNF inhibitors, patients in the Litfulo group were at an increased risk of developing cardiovascular events.

Similarly, the risk of thromboembolic events such as deep vein thrombosis, pulmonary embolism, and strokes was more in patients receiving Litfulo vs TNF inhibitors. One case of retinal artery occlusion was also reported.

Side effects of Litfulo (Ritlecitinib):

In clinical trials, the following side effects were reported:

  • Headache

  • Diarrhea, stomatitis

  • Rashes, urticaria, acne, folliculitis, eczema

  • Herpes zoster

  • Fever and dizziness

  • Elevated muscle enzymes

  • Anemia, lymphopenia, raised liver enzymes

Litfulo (Ritlecitinib) Mechanism of Action:

Ritlecitinib is a JAK inhibitor. It permanently inhibits the JAK-3 receptors and TEC (tyrosine kinase expressed in hepatocellular carcinoma) by blocking the ATP-binding sites.

In affected cells, cytokines bind to JAK-3 receptors and phosphorylate STAT proteins. Litfulo (Ritlecitinib) inhibits this phosphorylation of the STAT proteins. 

In addition, Ritlecitinib also acts by blocking the TEC pathway, however, the exact and dominant pathway by which Ritlecitinib exerts its action is not known.

Effect of QT-interval: None

Absorption: 64%

Peak plasma levels: one hour after intake.

Effect of food intake: The maximum plasma concentration may be reduced by 32% when it is taken with a high-fat meal.

Excretion: Urine: 66%, Feces: 20%,

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