@mcc At this point, peptide therapy for RA is in very early stages. Here is a recent article from Science Direct:
https://www.sciencedirect.com/science/article/abs/pii/S0024320522009572
Most studies use injected or IV patient-specific peptides to boost the action of DMARD drugs like methotrexate or leflunomide.

Nothing I have read indicates it is effective, safe or wise to purchase injectable peptides on line for home treatment.

Have you talked to your rheumatologist about seeking a clinical stude of peptides to participate in?