What is the management approach for a patient taking biologics for psoriatic arthritis who develops colitis?

Management of Colitis in Patients Taking Biologics for Psoriatic Arthritis

For patients taking biologics for psoriatic arthritis who develop colitis, switch to a TNF inhibitor monoclonal antibody (such as infliximab or adalimumab) as these agents are effective for both psoriatic arthritis and inflammatory bowel disease. 1

Causes of Colitis in Patients on Biologics for Psoriatic Arthritis

Medication-Induced Colitis

• IL-17 inhibitors: Can exacerbate or unmask inflammatory bowel disease (IBD) 2
• Drug-induced colitis: From concomitant medications
• Opportunistic infections: Including bacterial, viral, and fungal pathogens that may cause colitis in immunosuppressed patients 1

Primary Inflammatory Bowel Disease

• Ulcerative colitis: May co-exist with psoriatic arthritis
• Crohn's disease: May co-exist with psoriatic arthritis

Diagnostic Approach

1. Stool studies:

   • Rule out infectious causes (C. difficile, bacterial pathogens)
   • Fecal calprotectin to assess inflammation

2. Colonoscopy with biopsies:

   • Essential to differentiate between IBD and other causes
   • Histopathology helps distinguish between UC, Crohn's, and medication-induced colitis

3. Imaging:

   • CT abdomen/pelvis or MR enterography to assess extent of disease

Management Algorithm

Step 1: Assess Severity of Colitis

• Mild: <4 stools/day, minimal symptoms
• Moderate: 4-6 stools/day, abdominal pain
• Severe: >6 bloody stools/day, fever, tachycardia, anemia

Step 2: Management Based on Current Biologic

If Patient is on IL-17 Inhibitor (secukinumab, ixekizumab):

1. Discontinue IL-17 inhibitor immediately 2
2. Switch to TNF inhibitor monoclonal antibody (infliximab or adalimumab) 1
   • Strong recommendation supported by moderate-quality evidence showing TNF monoclonal antibodies are effective for both IBD and psoriatic arthritis 1
   • Wait at least one half-life of the previous biologic before initiating new therapy 2

If Patient is on IL-12/23 Inhibitor (ustekinumab):

1. Continue therapy if colitis is mild
2. Optimize dosing through therapeutic drug monitoring 1
3. Consider switching to TNF inhibitor if inadequate response

If Patient is on TNF Inhibitor:

1. Rule out paradoxical inflammation or antibody formation
2. Consider therapeutic drug monitoring to optimize dosing 1
3. Switch to different TNF inhibitor monoclonal antibody if on etanercept (which is less effective for IBD) 1

If Patient is on JAK Inhibitor (tofacitinib):

1. Consider dose optimization as tofacitinib is approved for both psoriatic arthritis and ulcerative colitis 3
2. Switch to TNF inhibitor if inadequate response

Step 3: Adjunctive Therapy

• Mild-moderate colitis: Consider adding mesalamine
• Moderate-severe colitis: Short course of corticosteroids
• Severe colitis: Hospitalization, IV steroids, expedited biologic therapy

Special Considerations

Combination Therapy

• Combination of apremilast with biologics may be considered safely in patients with inadequate response to biologics alone 4
• Consider low-dose methotrexate with infliximab to decrease antibody formation and improve efficacy 1

Monitoring

• Regular clinical assessment: Every 3-6 months
• Laboratory monitoring: CBC, CRP, liver enzymes, renal function
• Therapeutic drug monitoring: Consider for infliximab during maintenance treatment 1
• Colonoscopy: For persistent symptoms despite therapy

Infection Risk

• Screen for opportunistic infections before initiating new biologic therapy
• Hold biologic therapy during active infections requiring antibiotics 1
• Exercise caution in patients with chronic hepatitis C infection 1

Patient Preferences

• Consider patient preferences regarding administration route (IV vs. subcutaneous) 5
• African-American/Black patients may have stronger preferences for IV administration 5
• Shared decision-making between patients and physicians is crucial when selecting biologic treatments 5

By following this algorithm, clinicians can effectively manage colitis in patients with psoriatic arthritis on biologic therapy, minimizing disease burden and optimizing outcomes for both conditions.