Tofacit

Uses

Rheumatoid Arthritis: Tofacit is used for the treatment of adult patients with moderately to severely active rheumatoid arthritis who have had an inadequate response or intolerance to methotrexate. It may be used as monotherapy or in combination with methotrexate or other nonbiologic disease-modifying antirheumatic drugs (DMARDs).

Psoriatic Arthritis: Tofacit is used for the treatment of adult patients with active psoriatic arthritis who have had an inadequate response or intolerance to methotrexate or other disease-modifying antirheumatic drugs (DMARDs).

Ulcerative Colitis: Tofacit is used for the treatment of adult patients with moderately to severely active ulcerative colitis (UC).

Tofacit is also used to associated treatment for these conditions: Polyarticular-course Juvenile Idiopathic Arthritis (JIA), Moderate Rheumatoid arthritis, Severe Rheumatoid arthritis

How Tofacit works

Rheumatoid arthritis is an autoimmune disease characterized by a dysregulation of pro-inflammatory cytokines including IL7, IL15, IL21, IL6, IFN-alpha, and IFN-beta. (3) Cytokines signalling results in tissue inflammation and joint damage by stimulating the recruitment and activation of immune cells via the janus kinase signalling pathway.

Tofacit is a partial and reversible janus kinase (JAK) inihibitor that will prevent the body from responding to cytokine signals. By inhibiting JAKs, tofacitinib prevents the phosphorylation and activation of STATs. The JAK-STAT signalling pathway is involved in the transcription of cells involved in hematopoiesis, and immune cell function. Tofacit works therapeutically by inhibiting the JAK-STAT pathway to decrease the inflammatory response. However, there is evidence to suggest that it may also achieve efficacy via other pathways as well.

Dosage

Tofacit dosage

Do not initiate Tofacitif absolute lymphocyte count <500 cells/mm3, an absolute neutrophil count (ANC) <1000 cells/mm3 or hemoglobin <9 gm/dL.

Rheumatoid Arthritis: Tofacit 5 mg twice daily or Tofacit 11 mg once daily.Recommended dosage in patients with moderate and severe renal impairment or moderate hepatic impairment is Tofacit 5 mg once daily.

Psoriatic Arthritis (in combination with nonbiologic DMARDs): Tofacit 5 mg twice daily or Tofacit 11 mg once daily. Recommended dosage in patients with moderate and severe renal impairment or moderate hepatic impairment is Tofacit 5 mg once daily.

Ulcerative Colitis:

• Tofacit 10 mg twice daily for at least 8 weeks; then 5 or 10 mg twice daily. Discontinue after 16 weeks of 10 mg twice daily, if adequate therapeutic benefit is not achieved. Use the lowest effective dose to maintain response.
• Recommended dosage in patients with moderate and severe renal impairment or moderate hepatic impairment: half the total daily dosage recommended for patients with normal renal and hepatic function.

Side Effects

The most commonly reported adverse reactions during the first 3 months in controlled clinical trials (occurring in greater than or equal to 2% of patients treated with Tofacit monotherapy or in combination with DMARDs) were upper respiratory tract infections, headache, diarrhea and nasopharyngitis.

Toxicity

Minimum lethal dose in rat: 500 mg/kg. Maximum asymptomatic dose in non human primate: 40 mg/kg.

Lymphatic, immune system, bone marrow and erythroid cell toxicity was seen in animal studies involving rate and monkeys. Doses used in these studies ranged from 1mg/kg/day to 10mg/kg/day, over a duration of 6 weeks to 6 months. Lymphopenia, neutropenia, and anemia is seen in human subjects and may call for an interruption or discontinuation of therapy if severe.

Reduced female fertility in rats was seen at exposures 17 times the maximum recommended human dose. Fertility may be impaired in human females and harm may be caused to unborn child. Carcinogenic potential is seen, however evidence for dose dependency is lacking.

Because the janus kinase pathway plays a role in stimulating the production of red blood cells and is involved in immune cell function, inhibition of this pathway leads to increased risk of anemia, neutropenia, lymphopenia, cancer and infection.

Lymphopenia, neutropenia, and anemia in human subjects may call for an interruption or discontinuation of therapy if severe.

Role of JAK inhibition in the development of gastrointestinal perforation is not known.

Precaution

Serious Infections: Avoid use of Tofacit during an active serious infection, including localized infections.

Gastrointestinal Perforations: Use with caution in patients that may be at increased risk.

Laboratory Monitoring: Recommended due to potential changes in lymphocytes, neutrophils, hemoglobin, liver enzymes and lipids.

Immunizations: Live vaccines: Avoid use with Tofacit.

Interaction

Potent inhibitors of Cytochrome P450 3A4 (CYP3A4) (e.g., Ketoconazole)

Recommended dose is Tofacit 5 mg once daily: One or more concomitant medications that result in both moderate inhibition of CYP3A4 and potent inhibition of CYP2C19 (e.g., fluconazole)

Recommended dose is Tofacit 5 mg once daily Potent CYP inducers (e.g.Rifampin): May result in loss of or reduced clinical response.

Food Interaction

• Avoid grapefruit products. Dose adjustments are required when administering CYP3A4 inhibitors (grapefruit) and CYP2C19 inhibitors with tofacitinib.
• Avoid St. John's Wort. This herb induces the CYP3A4 metabolism of tofacitinib and may reduce its serum concentration.
• Take with or without food.

Tofacit Cholesterol interaction

[Moderate] Hyperlipidemia has been observed in patients receiving tofacitinib.

Patients with preexisting hyperlipidemia may require close monitoring during therapy, and adjustments made accordingly in their lipid-lowering regimen.

Tofacit therapy should be administered with caution in these patients.

Tofacit Drug Interaction

Major: mycophenolate mofetil, adalimumabModerate: aspirin, oxycodone, omeprazole, bifidobacterium infantis / lactobacillus acidophilus, tramadolUnknown: amoxicillin / clavulanate, celecoxib, ubiquinone, dexlansoprazole, ethanol, ipratropium, escitalopram, pregabalin, rimegepant, acetaminophen, tiotropium, levothyroxine, cholecalciferol

Tofacit Disease Interaction

Major: cardiovascular risk, malignancy, thrombosis, viral reactivation, GI perforation, hepatic disorder, infections, renal disease, tuberculosisModerate: cytopenias, diabetes, GI obstruction, hyperlipidemia

Volume of Distribution

Vd= 87L after intravenous administration. Distribution is equal between red blood cells and plasma.

Elimination Route

74% oral absorption (absolute bioavailability), with peak plasma concentrations (T _max) achieved in 0.5-1 hour.

Administration with fatty meals does not alter AUC but reduces Cmax by 32%.

Half Life

~3 hours

Elimination Route

70% metabolized in the liver by CYP3A4 (major) and CYP2C19 (minor). Metabolites produced are inactive. 30% renally eliminated as unchanged drug.

Pregnancy & Breastfeeding use

Pregnancy Category C. There are no adequate and well controlled studies in pregnant women. Tofacit should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

It is not known whether Tofacit is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from Tofacit, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug for the mother

Contraindication

None

Special Warning

Pediatric Use: The safety and effectiveness of Tofacit in pediatric patients have not been established.

Geriatric Use: The frequency of serious infection among Tofacit-treated subjects 65 years of age and older was higher than among those under the age of 65. As there is a higher incidence of infections in the elderly population in general, caution should be used when treating the elderly.

Storage Condition

Store at 20°C to 25°C

Innovators Monograph

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