Tofacitinib Drug

Indications

Tofacitinib is a medication used to treat autoimmune diseases like rheumatoid arthritis, psoriatic arthritis, ulcerative colitis, ankylosing spondylitis, and juvenile idiopathic arthritis. It’s part of a group of drugs called Janus kinase (JAK) inhibitors.

Tofacitinib FDA Approval

Tofacitinib drug discovered and developed by the National Institutes of Health and Pfizer, It was approved for use in the United States in November 2012. An extended-release version was later approved in February 2016. It’s now available as a generic medication.

In September 2020, the FDA approved tofacitinib to treat children and adolescents aged two years and older with active polyarticular course juvenile idiopathic arthritis.

In December 2021, the FDA approved, adults with active ankylosing spondylitis.

The FDA approved tofacitinib in May 2018 for treatment of ulcerative colitis.

Mechanism of Action

Tofacitinib works by targeting Janus kinase (JAK) enzymes, which play a crucial role in transmitting signals within cells, especially those related to immune cell function. These enzymes are involved in activating Signal Transducers and Activators of Transcription (STATs), which in turn regulate gene expression and other intracellular activities.

Tofacitinib intervenes in this process by inhibiting JAKs, specifically blocking their ability to phosphorylate and activate STATs. This action helps to modulate immune responses and reduce inflammation.

It’s worth noting that JAK enzymes work in pairs, such as JAK1/JAK2, JAK1/JAK3, JAK1/TyK2, and JAK2/JAK2. Tofacitanib has been shown to inhibit these combinations in laboratory studies, with varying degrees of effectiveness. However, the exact significance of targeting specific JAK combinations for therapeutic benefit is still being investigated.

Tofacitinib Side Effects

Common Adverse Reactions

During the first three months of controlled clinical trials, the most commonly reported adverse reactions (occurring in 2% or more of patients) with tofacitanib citrate monotherapy or in combination with DMARDs were:

• Upper respiratory tract infections
• Headache
• Diarrhea
• Nasopharyngitis (common cold)

Boxed Warning

The FDA requires tofacitinib to carry a boxed warning on its label due to potential risks, including:

• Possible injury and death from infections, lymphoma, and other malignancies.
• Serious infections leading to hospitalization or death, including tuberculosis, bacterial, invasive fungal, viral, and other opportunistic infections.
• Increased risk of Epstein Barr virus-associated post-transplant lymphoproliferative disorder in renal transplant patients on immunosuppressive medications.
• Avoiding use during active serious infections, including localized infections.

Cautionary Measures

Doctors are advised to exercise caution in patients who may be at increased risk of gastrointestinal perforations. Laboratory monitoring is recommended due to potential changes in:

• Lymphocytes
• Neutrophils
• Hemoglobin
• Liver enzymes
• Lipids

Dosage Adjustment

While tofacitanib claims to have no contraindications, doctors should reduce the patient’s dosage when combined with:

• Potent inhibitors of cytochrome P450 3A4 (CYP3A4), such as ketoconazole.
• One or more combined medications resulting in both moderate inhibition of CYP3A4 and potent inhibition of CYP2C19, such as fluconazole.

Immunizations

Tofacitinib users should avoid immunizations with live vaccines.

Dosages And Administration

Tofacitinib dose for Rheumatoid Arthritis & Psoriatic Arthritis Treatment:

• Recommended dose: 5 mg twice daily or extended-release (XR) 11 mg once daily
• Subjects with moderate to severe renal impairment or moderate hepatic impairment: Recommended 5 mg once daily

Ulcerative Colitis Treatment:

• Recommended dose: 10 mg twice daily for eight weeks initially, then decreased to 5 mg twice daily (Note: Tofacitinib 10 mg twice daily is only FDA approved for ulcerative colitis treatment)
• Discontinue if adequate therapeutic response not achieved by 16 weeks at 10 mg twice a day dosage
• Subjects with moderate to severe renal impairment or moderate hepatic impairment: Recommended half of the daily dosage compared to those with normal renal and hepatic function

Polyarticular Course Juvenile Idiopathic Arthritis Treatment:

• Recommended dose: 5 mg twice daily (oral solution) or weight-based equivalent twice daily
• Bodyweight 10 kg to less than 20 kg: 3.2 mg (3.2 mL oral solution) twice daily
• Bodyweight 20 kg to less than 40 kg: 4 mg (4 mL oral solution) twice daily
• Bodyweight greater than 40 kg: 5 mg (one 5 mg tablet or 5 mL oral solution) twice daily

Tofacitinib Drug Interaction

• Immunosuppressants: Combining tofacitinib with other immunosuppressants such as azathioprine, cyclosporine, or tacrolimus may increase the risk of immunosuppression and infections.
• Biologic DMARDs (Disease-Modifying Antirheumatic Drugs): Concurrent use of tofacitinib with biologic DMARDs like etanercept, adalimumab, or infliximab may increase the risk of infections and should be used cautiously.
• Anticoagulants and Antiplatelet Drugs: Tofacitinib may increase the risk of bleeding when used with anticoagulant drugs such as warfarin or antiplatelet drugs like aspirin.
• Live Vaccines: Tofacitinib may interfere with the effectiveness of live vaccines. Patients should avoid live vaccines while taking tofacitanib.
• Strong CYP3A4 Inhibitors: Drugs that inhibit the enzyme CYP3A4, such as ketoconazole or ritonavir, can increase the concentration of tofacitinib in the blood, leading to potential toxicity.
• Moderate CYP3A4 Inhibitors: Drugs that moderately inhibit CYP3A4, like fluconazole or diltiazem, may also increase tofacitinib levels and require dosage adjustments.
• CYP3A4 Inducers: Drugs that induce CYP3A4, such as rifampin or phenytoin, may decrease the concentration of tofacitinib in the blood, reducing its effectiveness.
• Grapefruit and Grapefruit Juice: Consumption of grapefruit or grapefruit juice should be avoided as it can increase the blood levels of tofacitinib.