What is the appropriate dosing regime for infliximab (chimeric monoclonal antibody against tumor necrosis factor-alpha) infusions for a 21-year-old woman with generalized plaque psoriasis weighing 98kg?

Infliximab Dosing Regimen for Plaque Psoriasis

For a 21-year-old woman with generalized plaque psoriasis weighing 98kg, the appropriate infliximab dosing regimen is 5 mg/kg administered intravenously at weeks 0,2, and 6 for induction, followed by maintenance infusions every 8 weeks thereafter. 1

Dosing Calculation

• For a 98kg patient, the appropriate dose would be 490mg (5 mg/kg × 98kg) per infusion 1
• This dose should be administered as an intravenous infusion over a period of 2 hours 1
• The standard induction regimen consists of infusions at weeks 0,2, and 6 1
• Following induction, maintenance infusions should continue every 8 weeks 1

Efficacy of Recommended Dosing

• At the recommended dose of 5 mg/kg, approximately 80% of patients achieve a 75% improvement in Psoriasis Area and Severity Index (PASI 75) by week 10 1, 2
• Continuous maintenance therapy (every 8 weeks) is superior to intermittent (as-needed) therapy for maintaining response 2
• The 5 mg/kg dose shows better maintenance of response through week 50 compared to lower doses (3 mg/kg) 2

Monitoring and Assessment

• Assess treatment response at week 10-14 to determine if continuation is appropriate 1
• According to British Association of Dermatologists (BAD) guidelines, patients should have a Dermatology Life Quality Index (DLQI) >10 and meet qualifying criteria to continue treatment 1
• National Institute for Health and Clinical Excellence (NICE) criteria recommend assessment at 10 weeks 1

Important Considerations

• Baseline screening is essential before initiating therapy:
  • Tuberculosis screening with purified protein derivative (PPD) test is required 1
  • Complete blood count (CBC), liver function tests (LFT), and hepatitis profile should be obtained 1
• Ongoing monitoring should include:
  • Periodic physical examinations 1
  • Consider yearly tuberculosis screening 1
  • Periodic CBC and LFT 1

Potential Adverse Effects

• Infusion reactions may occur in up to 20% of patients, ranging from mild to severe 1
• Risk of serious infections, including tuberculosis, is increased with anti-TNF therapy 1
• Development of antibodies to infliximab may reduce efficacy over time 1, 3

Optimizing Long-term Outcomes

• Continuous therapy is preferred over intermittent therapy to maintain response and reduce the risk of antibody formation 1, 2
• Consider combination with methotrexate in patients who show reduced response over time, as this may reduce immunogenicity and improve long-term efficacy 1, 4
• If disease control worsens with standard dosing, dose adjustments may be considered, but should be based on documented inadequate response 5

Common Pitfalls to Avoid

• Failing to screen for tuberculosis and other infections before initiating therapy 1
• Using intermittent therapy, which is associated with reduced efficacy and increased risk of antibody formation 2
• Discontinuing therapy prematurely before adequate assessment of response 1
• Not recognizing that maintenance of disease control may be possible with standard dosing 5