The Science Behind Skyrizi

Skyrizi belongs to a class of medications called interleukin-23 (IL-23) inhibitors. It contains the active ingredient risankizumab-rzaa, a specialized monoclonal antibody designed to selectively bind to the p19 subunit of IL-23, a cytokine (signaling protein) that plays a crucial role in inflammatory and immune responses.

In people with psoriasis, the immune system produces excessive amounts of certain cytokines, including IL-23. This overproduction triggers inflammation and accelerates the growth cycle of skin cells, causing them to build up rapidly on the surface of the skin. By specifically targeting and neutralizing IL-23, Skyrizi helps reduce the inflammatory cascade that leads to the characteristic red, scaly plaques of psoriasis.

Administration and Treatment Schedule

Skyrizi is administered as a subcutaneous injection, meaning it's injected just under the skin rather than into a muscle or vein. The standard dosing schedule begins with two 75 mg injections (150 mg total) given at week 0 and week 4, followed by maintenance doses every 12 weeks thereafter.

The medication comes in pre-filled syringes or pens, making self-administration possible after proper training from a healthcare provider. The most common injection sites include the thighs and abdomen. The extended interval between maintenance doses (once every 3 months) offers convenience compared to some other psoriasis treatments that require more frequent administration.

Clinical Efficacy and Response Time

Clinical trials have demonstrated significant efficacy for Skyrizi in treating moderate to severe plaque psoriasis. In pivotal studies, approximately 75% of patients achieved PASI 90 (Psoriasis Area and Severity Index score improvement of 90% or more) after 16 weeks of treatment, indicating near-complete clearance of psoriasis symptoms.

Most patients begin to notice improvements in their skin within 4-8 weeks after starting treatment. However, maximum benefits typically develop between weeks 16-24. The medication has also shown durability in its effects, with many patients maintaining their response through continuous treatment over multiple years.

Biologic Treatment Comparison

When considering psoriasis treatments, it's important to understand how Skyrizi compares to other biologics. AbbVie, the manufacturer of Skyrizi, positions it as a highly selective IL-23 inhibitor with a favorable dosing schedule.

Other biologic options include TNF inhibitors like Amgen's Enbrel (etanercept), IL-17 inhibitors such as Novartis's Cosentyx (secukinumab), and older IL-12/23 inhibitors like Janssen's Stelara (ustekinumab).

Each medication works through different mechanisms:

  • TNF inhibitors: Block tumor necrosis factor, a broader inflammatory protein
  • IL-17 inhibitors: Target interleukin-17, another cytokine in the inflammatory cascade
  • IL-12/23 inhibitors: Block both IL-12 and IL-23 pathways
  • IL-23 inhibitors (like Skyrizi): Selectively target only the IL-23 pathway

This selectivity potentially offers an advantage in terms of safety profile while maintaining high efficacy. The quarterly maintenance dosing of Skyrizi also compares favorably to some alternatives that require monthly injections.

Safety Profile and Considerations

As with any medication that affects the immune system, Skyrizi carries certain risks. The most common side effects reported in clinical trials include upper respiratory infections, headache, fatigue, injection site reactions, and fungal skin infections.

Before starting Skyrizi, patients must be screened for tuberculosis, as the medication may increase the risk of reactivating latent TB. Individuals with active infections should not begin treatment until the infection resolves. CDC guidelines recommend updating vaccinations before starting biologic therapy, as live vaccines should be avoided during treatment.

Compared to some older biologics, Skyrizi's selective mechanism may offer advantages in terms of safety. By targeting only the IL-23 pathway rather than multiple immune components, it may potentially reduce the broader immune suppression seen with less selective medications. However, long-term safety data continues to accumulate as the medication has been approved since 2019.

Conclusion

Skyrizi represents a significant advancement in the treatment of moderate to severe plaque psoriasis through its selective targeting of the IL-23 pathway. Its quarterly maintenance dosing schedule and high rates of skin clearance make it an attractive option for many patients struggling with psoriasis. While the medication has demonstrated impressive efficacy in clinical trials, the decision to start any biologic therapy should involve careful consideration of individual health factors, treatment goals, and discussions with healthcare providers specializing in dermatology. As with all biologics, ongoing monitoring is essential to ensure safety and optimize outcomes. For patients who have not found relief with conventional treatments, Skyrizi offers another tool in the expanding arsenal against inflammatory skin conditions.

Citations

This content was written by AI and reviewed by a human for quality and compliance.