Risankizumab

• Plaque Psoriasis
• Psoriatic Arthritis
• Crohn's Disease

Risankizumab is a humanized monoclonal antibody that selectively blocks interleukin-23 (IL-23) by binding to its p19 subunit. It is used to treat moderate-to-severe plaque psoriasis, psoriatic arthritis, and Crohn's disease.

Mechanism of Action

Risankizumab targets the IL-23 pathway:

• IL-23 p19 subunit binding: Selectively binds to the p19 subunit of IL-23
• Blocks IL-23 signaling: Prevents IL-23 from binding to its receptor
• Reduces Th17 cell activity: IL-23 is critical for survival and function of Th17 cells
• Decreases inflammatory cytokines: Reduces IL-17, IL-22, and other downstream mediators

IL-23 is a key driver of inflammation in psoriasis, psoriatic arthritis, and inflammatory bowel disease.

Available Formulations

• Prefilled syringe: 75 mg/0.83 mL (for psoriasis)
• Prefilled pen: 150 mg/mL (for psoriasis)
• IV solution: 600 mg/10 mL (for Crohn's disease induction)

Medical Uses

FDA-Approved Indications:

• Moderate-to-severe plaque psoriasis in adults who are candidates for systemic therapy or phototherapy
• Active psoriatic arthritis in adults
• Moderately to severely active Crohn's disease in adults

Dosing Guidelines

Plaque Psoriasis:

• 150 mg subcutaneously at weeks 0 and 4, then every 12 weeks

Psoriatic Arthritis:

• 150 mg subcutaneously at weeks 0 and 4, then every 12 weeks
• May be used alone or with non-biologic DMARDs

Crohn's Disease:

• Induction: 600 mg IV at weeks 0, 4, and 8
• Maintenance: 360 mg subcutaneously at week 12 and every 8 weeks thereafter

Important Safety Information

Contraindications:

• History of serious hypersensitivity reaction to risankizumab

Warnings and Precautions:

• Infections: Increased risk of infections; evaluate for tuberculosis before initiating
• Tuberculosis: Test for latent TB; treat before starting if positive
• Hepatotoxicity (Crohn's disease): Monitor liver enzymes during IV induction
• Immunizations: Complete all age-appropriate vaccinations before starting; avoid live vaccines during treatment

Drug Interactions

No formal drug interaction studies have been conducted. As a monoclonal antibody, risankizumab is not expected to interact via cytochrome P450 pathways.

Considerations:

• Live vaccines: Avoid during treatment
• CYP450 substrates: Formation of IL-23 inhibitor-induced CYP enzymes may normalize; monitor narrow therapeutic index drugs

Special Populations

• Hepatic Impairment: Not formally studied; monitor liver enzymes during Crohn's disease induction
• Renal Impairment: Not expected to affect pharmacokinetics
• Pregnancy: Limited data; use only if benefit outweighs risk
• Lactation: Unknown if excreted in milk; consider risk vs benefit
• Elderly: No dose adjustment
• Pediatric: Not approved for patients <18 years