Risankizumab

• Plaque Psoriasis
• Psoriatic Arthritis
• Crohn's Disease

Risankizumab-rzaa is a humanized monoclonal antibody that selectively targets the p19 subunit of interleukin-23 (IL-23). It is approved for moderate-to-severe plaque psoriasis, active psoriatic arthritis, and moderately to severely active Crohn's disease. Many patients achieve near-complete skin clearance and durable joint or gut remission with quarterly subcutaneous dosing, making it one of the more convenient biologics in current use.

Mechanism of Action

IL-23 is a heterodimeric cytokine composed of p19 and p40 subunits. It is produced by activated dendritic cells and macrophages and serves as a master regulator of the Th17 immune axis, which drives much of the inflammation in psoriasis, psoriatic arthritis, and inflammatory bowel disease. Risankizumab binds the unique p19 subunit, blocking IL-23 from engaging its receptor on Th17 cells.

The downstream effect is a marked reduction in IL-17A, IL-17F, IL-22, and other Th17-derived cytokines that drive keratinocyte hyperproliferation, neutrophilic inflammation, and epithelial barrier disruption. Because the p40 subunit is shared with IL-12, agents like ustekinumab block both IL-12 and IL-23. Selective p19 blockade with risankizumab spares IL-12 signaling and Th1 immunity, which may translate into a more favorable infection profile while still delivering strong efficacy in IL-23-driven disease. Pivotal trials in plaque psoriasis showed PASI 90 responses in roughly three-quarters of patients at week 16, with sustained response over years of maintenance dosing — a remarkable benchmark for a once-quarterly subcutaneous regimen.

In Crohn's disease, IL-23 blockade reduces mucosal inflammation, promotes endoscopic healing, and improves patient-reported outcomes. The IV induction and SC maintenance schedule for IBD is built around the higher tissue burden of inflammation in the gut.

Clinical Use

Risankizumab is generally considered for adults with moderate-to-severe plaque psoriasis who are candidates for systemic therapy or phototherapy, particularly when topicals and traditional systemics like methotrexate have failed or are not tolerated. In psoriatic arthritis, it can be used alone or with non-biologic DMARDs and is particularly attractive for patients with prominent skin disease. In Crohn's disease, IV induction is followed by maintenance subcutaneous dosing and offers an option for patients whose disease has failed prior biologics, including TNF inhibitors.

Alternatives within the IL-23 class include guselkumab and tildrakizumab; IL-17 inhibitors such as secukinumab, ixekizumab, and brodalumab; TNF inhibitors like adalimumab, etanercept, infliximab, certolizumab, and golimumab; and oral options such as apremilast, deucravacitinib, tofacitinib, and upadacitinib. For psoriatic arthritis with prominent enthesitis or axial disease, IL-17 or TNF inhibitors may be preferred. In patients with concurrent uveitis or inflammatory bowel disease, monoclonal anti-TNF agents like infliximab or adalimumab carry stronger evidence for those manifestations than IL-17 inhibitors. The National Psoriasis Foundation and the Crohn's and Colitis Foundation maintain useful condition resources. Our dermatologic care page covers our broader approach to inflammatory skin disease.

How to Take It

Risankizumab for psoriasis and psoriatic arthritis is given as a subcutaneous injection at weeks 0 and 4, then every 12 weeks. The on-body injector or prefilled pen is administered into the thigh or abdomen, rotating sites each time and avoiding skin that is bruised, tender, scaly, or actively involved with psoriasis. The drug is stored in the refrigerator and should be allowed to come to room temperature for 15 to 30 minutes before injection to reduce stinging. For Crohn's disease, induction uses three IV infusions at weeks 0, 4, and 8, followed by 360 mg subcutaneous maintenance every 8 weeks.

Missed doses should be administered as soon as possible, and the schedule restarted from that point. Most patients see meaningful psoriasis improvement within 12 to 16 weeks, with maximal effect around 6 to 12 months. The injection is typically well tolerated; mild local reactions usually resolve within a day or two. Patients should keep a vaccination plan up to date — the recombinant zoster vaccine, pneumococcal vaccines, annual influenza, and updated COVID-19 vaccines should be administered ideally before initiating therapy, since live vaccines are contraindicated during treatment. The HPV vaccine is also worth considering for younger adults.

Monitoring and Follow-Up

Before starting any biologic, screen for latent tuberculosis (interferon-gamma release assay or PPD with chest X-ray) and for hepatitis B and C. A baseline CBC and liver enzymes are reasonable; for Crohn's induction, monitor liver enzymes more closely because hepatotoxicity has been reported with the IV regimen. The components of these panels are summarized in our lab work overview. Monitor disease activity with PASI scores in psoriasis, joint counts and CRP in arthritis, and fecal calprotectin or endoscopy in Crohn's. Reassess for infections at every visit, and pause dosing during serious active infection.

Dermatologic surveillance for non-melanoma skin cancers is a reasonable practice in long-term biologic recipients, particularly given Florida's high UV exposure — see our skin cancer screening in St. Petersburg article for our local approach. Annual primary care visits should also include cardiovascular risk reassessment, since psoriasis itself carries elevated cardiovascular risk that biologic therapy may partially mitigate.

Patients with psoriatic arthritis should have joint counts and function assessed at each visit, with imaging considered if new joint involvement appears. Crohn's patients benefit from periodic colonoscopic surveillance per gastroenterology recommendations, especially after years of disease, because long-standing colitis raises colorectal cancer risk. Mental health screening for depression and anxiety is reasonable for any chronic inflammatory disease — psoriasis carries elevated rates of both, partly biologic and partly secondary to visible disease and stigma.

Switching biologics deserves a careful approach. When risankizumab fails or loses effect, options include switching within the IL-23 class, moving to an IL-17 inhibitor, returning to a TNF inhibitor (if not previously failed), or trying an oral agent. Decisions depend on the predominant manifestation (skin, joints, gut), prior treatment history, comorbidities, patient preference for route and frequency, and insurance coverage. Bridging therapy, monitoring for symptom flare, and adequate washout between agents reduce risk during transitions.

Cost and access can be significant practical barriers. Patient assistance programs from the manufacturer and copay support cards can reduce out-of-pocket costs for eligible patients with commercial insurance, and biosimilar competition is gradually expanding for some biologic classes (though risankizumab does not yet have approved biosimilars). Specialty pharmacies coordinate prior authorization, shipping, and adherence support for biologics — patients should be connected with these services rather than left to navigate insurance complexity on their own.

Lifestyle measures complement biologic therapy. Smoking cessation improves psoriasis severity, slows joint damage in psoriatic arthritis, and reduces Crohn's flare frequency. Weight loss in patients with obesity often improves treatment response and may allow lower biologic doses. Mediterranean-pattern eating, regular physical activity, stress management, and good sleep hygiene each contribute to control of inflammatory disease. Alcohol reduction is particularly important in psoriasis, where heavy drinking is associated with worse disease and reduced treatment response. For Crohn's disease, dietary individualization — sometimes guided by a registered dietitian — can identify trigger foods and ensure nutritional adequacy during flares and remission alike. Patients with significant disease activity often benefit from monitoring of micronutrients including vitamin B12, iron, vitamin D, and folate.

Special Populations

Risankizumab is not approved in children. There is no formal renal or hepatic dose adjustment, but liver enzymes should be monitored during Crohn's induction. Pregnancy data are limited; the drug crosses the placenta in the third trimester, and exposed infants should not receive live vaccines for at least 6 months after birth. Older adults and patients with chronic infections like recurrent skin abscesses or bronchiectasis warrant individualized risk-benefit discussion. Although uncommon, hypersensitivity reactions can occur and should prompt discontinuation.

When to Contact Your Doctor

Report new fever, cough, night sweats, weight loss, or anything that suggests reactivated tuberculosis. Severe injection-site reactions, generalized rash, hives, swelling of the face or throat, or wheezing after dosing require immediate evaluation. Worsening psoriasis or new joint swelling despite ongoing therapy should prompt a visit. During Crohn's induction, jaundice, dark urine, or right-upper-quadrant pain warrant urgent liver enzyme testing. Persistent diarrhea, rectal bleeding, or unintended weight loss suggests inadequate IBD control or a complication that needs prompt evaluation.

If you have questions about risankizumab or your treatment plan, our team at Zimmer Medical Group can help — contact us or schedule a visit.