Is it safe for people with Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease (MOGAD) and active MOG (Myelin Oligodendrocyte Glycoprotein) titers to take quinine for psoriatic arthritis pain?

Safety of Quinine for Psoriatic Arthritis Pain in Patients with MOGAD

Quinine is not recommended for patients with MOGAD and active MOG titers who have psoriatic arthritis pain due to potential neurological risks.

Rationale for Recommendation

Patients with Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease (MOGAD) have a demyelinating condition that affects the central nervous system. While quinine has been used for muscle cramps and some arthritis symptoms, there are several important considerations:

1. Neurological Risk: Quinine has potential neurotoxic effects that could theoretically exacerbate or trigger neurological symptoms in patients with pre-existing demyelinating conditions like MOGAD 1.

2. Lack of Evidence: There is no specific research on quinine use in MOGAD patients, and the potential interaction between quinine and the pathophysiology of MOGAD is unknown.

3. Alternative Treatments: Multiple safer and more effective treatment options exist for psoriatic arthritis that are supported by guidelines 2.

Recommended Treatment Approach for Psoriatic Arthritis in MOGAD Patients

First-line Options:

• NSAIDs: For mild symptoms, NSAIDs may be used with caution, monitoring for cardiovascular and gastrointestinal risks 2.
• Local Glucocorticoid Injections: For isolated joint involvement, enthesitis, or dactylitis 2.

Second-line Options:

• Disease-Modifying Antirheumatic Drugs (DMARDs):
  • Methotrexate is typically the preferred DMARD for psoriatic arthritis with joint involvement 2.
  • Careful monitoring of liver function is essential as methotrexate may have increased hepatic toxicity in psoriatic arthritis 2.

For Moderate-to-Severe Disease:

• TNF Inhibitor Monoclonal Antibodies (infliximab, adalimumab) are preferred over other biologics in patients with neuroinflammatory conditions 2, 3.
• These agents are effective for both psoriatic arthritis and have less risk of exacerbating neurological symptoms compared to other biologics.

Important Considerations for MOGAD Patients

• Avoid IL-17 Inhibitors: These may potentially worsen neuroinflammatory conditions 3.
• Monitor Neurological Status: Regular assessment for any new or worsening neurological symptoms during treatment.
• Coordinate Care: Management should involve both rheumatology and neurology to balance treatment of psoriatic arthritis while protecting neurological status.

Why Not Quinine or Antimalarials?

While chloroquine has been studied for psoriatic arthritis with some positive results 4, antimalarials must be used with extreme caution in patients with neurological conditions. The 2009 and 2019 guidelines specifically note that "gold salts, chloroquine and hydroxychloroquine are not recommended for use in PsA" 2.

Quinine specifically has been associated with:

• Risk of serious adverse events, including thrombocytopenia (0.12%) 1
• Potential neurotoxicity that could theoretically interact with the demyelinating pathology of MOGAD
• Limited evidence for efficacy in arthritis pain compared to established treatments

Treatment Algorithm

1. Assess Disease Severity:

   • Mild: Consider NSAIDs with appropriate monitoring
   • Moderate-to-severe: Proceed to DMARDs or biologics

2. For Persistent Symptoms:

   • Start with methotrexate (if no contraindications)
   • Monitor liver function closely

3. For Inadequate Response to DMARDs:

   • Consider TNF inhibitor monoclonal antibodies (infliximab or adalimumab)
   • Avoid etanercept if inflammatory bowel symptoms are present 3

4. For Refractory Cases:

   • Consider combination therapy with methotrexate and TNF inhibitor
   • Regular monitoring of both arthritis symptoms and neurological status

The treatment of psoriatic arthritis in patients with MOGAD requires careful consideration of both conditions to optimize outcomes while minimizing risks of neurological deterioration.