JAK Inhibitors

JAK Inhibitor Drugs

JAK Inhibitor Drugs

JAK inhibitors are a group of medications that can treat various types of arthritis, including rheumatoid arthritis (RA), cancer, dermatological conditions like atopic dermatitis and alopecia areata, and some bowel conditions like ulcerative colitis and inflammatory bowel disease.

How JAK Inhibitors Work

These medications inhibit the activity of one or more of the Janus kinase enzymes (JAK1, JAK2, JAK3, and TYK2). These enzymes promote inflammation, and they are involved in some diseases. Inflammation is limited when the enzyme signaling pathways are interrupted, which can help some autoimmune diseases.

Uses of JAK Inhibitors

Excess inflammation can be problematic in conditions such as RA, cancer, and immune conditions. JAK inhibitors can help reduce inflammation.

Cytokines

Cytokines are inflammatory proteins that attach to receptors on immune cells. This signals JAK enzymes to add chemical phosphate to their receptors, which attracts another type of protein called signal transducer and activator of transcription (STAT) proteins. The STAT proteins further increase inflammation.

Biologic Drugs vs. JAK Inhibitors

Another class of drugs called biologics are also commonly used to treat arthritis and other autoimmune conditions. Both types of drugs belong to the disease-modifying antirheumatic drugs (DMARDs) family. Biologics are made from animal or plant cells, and JAK inhibitors are synthetic.

Xeljanz (Tofacitinib)

Xeljanz was approved by the Food and Drug Administration (FDA) in 2012 and is among the most often prescribed drugs in its class.

Research Highlights

Data from phase II studies show the drug effectively relieves symptoms in people with plaque psoriasis, taking 3 mg or less per day over 12 weeks.

Possible Side Effects

There are side effects common to all JAK inhibitors, and each JAK inhibitor has its own list of potential adverse events.

Common Side Effects

Some common side effects that may go away with use include:

• Diarrhea
• Headache
• Cold symptoms, such as sore throat or runny or stuffy nose
• Dizziness
• Easy bruising
• Weight gain
• Bloating and gas
• Fatigue

Immune-System Suppression

Similar to biologics and traditional DMARDs, JAK inhibitors suppress the immune system. While that makes them beneficial, it increases vulnerability to severe infections—especially upper respiratory and urinary tract infections.

Contraindications and Warnings

JAK inhibitors can also cause anemia in some people. This is due to how they affect proteins the body needs to make red blood cells.

Summary

JAK inhibitors are another line of defense in treating autoimmune conditions like arthritis, cancer, autoimmune skin conditions, and irritable bowel disease. They work by interrupting a chain of reactions that lead to inflammation. While they have a similar result as biologics, they are taken orally rather than through an injection or infusion. However, these medications are relatively new, and researchers are still learning more about their long-term safety.