Leflunomide is another traditional oral DMARD that is administered daily. It has be shown to be effective in PsA, with only a modest effect in improving skin lesions. 12 Laboratory monitoring is identical to that required with MTX. Adverse effects (AEs) include diarrhea and increased risk of elevated transaminases. 9 Sulfasalazine (SSZ) is also used as a traditional DMARD and shown to have an effective clinical response in treating peripheral arthritis but not in axial or skin disease. 9,12 Not all studies have shown effective responses to SSZ. The primary AE is gastrointestinal, making this a frequently discontinued medication. 2 Cyclosporine is more commonly used in psoriasis but can be used on its own or with MTX for treating patients with PsA. 10 It is often not tolerated well and frequently discontinued, due to major AEs, including hypertension and renal dysfunction. 2,10
These traditional DMARDs are usually given for 3 to 6 months. 13 After this initial period, the patient’s clinical response is reassessed, and the need for changing therapy to another DMARD or biologic is determined.
Biologic Therapies
With the discovery of TNFα as a potent cytokine in inflammatory arthritis came a new class of medications that has provided patients and providers with more effective treatment options. This category of medications is known as tumor necrosis factor inhibitors (TNFis). Five medications have been developed that target TNFα, each in its own way: etanercept, infliximab, adalimumab, golimumab, and certrolizumab pegol. These medications were initially studied in patients with rheumatoid arthritis, with further clinical trials performed for treatment of PsA. Each is prescribed differently: Adalimumab and certrolizumab are given SC every 2 weeks, etanercept is given weekly, and golimumab is given once a month. Infliximab is the only medication prescribed as an infusion, which is administered every 8 weeks after receiving 3 loading doses.
Studies have shown that all TNFis are effective in treating PsA: improving joint disease activity, inhibiting progression of structural damage, and improving function and overall quality of life .10 The TNFi drugs also improve psoriasis along with dactylitis, enthesitis, and nail changes. 13 Patients with
axial disease benefit from TNFi, but the evidence of TNFi effectiveness is extrapolated from studies in axial spondyloarthritis. 13,14 Tumor necrosis
factor inhibitors can be used as monotherapy, although there is some evidence for using TNFi drugs with MTX in PsA. Combination therapy can potentially prolong the survival of the TNFi drug or prevent formation of antidrug antibodies. 14,15
The current evidence for monotherapy vs combination therapy in patients with PsA is not consistent, and no formal guidelines have been developed to guide physicians one way or another. The TNFi drugs are generally well tolerated, although the patient needs to learn how to self-inject if given the SC route. Adverse effects include infusion or injection site reactions and infections. Prior to starting a TNFi, it is prudent to screen for latent tuberculosis infection as well as hepatitis B and C, given the risk of reactivation. Clinical response is monitored for 3 months, and if remission or low disease activity is not reached, a different TNFi may be tried. 13 Importantly, patients receiving infliximab without clinical improvement in 3 months may have their dose and frequency increased before switching to an alternative TNFi. Some studies show that a trial of a second TNFi has a less potent response than with a first TNFi, and the drug survival is shorter in duration. 13