Rheumatoid Arthritis Flashcards
What effect have DMARDs been shown to have in RA?
Slow course of disease
Induce remission
Prevent further destruction of joints and involved tissues
What treatment should be given when a patient is diagnosed with RA?
Initiation of DMARDs within 3 months, in addition to NSAIDs, low-dose corticosteroids, physical therapy, and occupational therapy
Why is therapy with DMARDs initiated rapidly in RA?
To stop the progression of the disease at earlier stage
Is methotrexate used alone or in combination therapy in rheumatoid arthritis?
Either
What kind of arthritis is methotrexate the mainstay treatment in?
Rheumatoid or psoriatic
What is the effect of methotrexate on the radiograph?
It slows the appearance of new erosions with involved joints
When does response to methotrexate occur?
Within 3 to 6 months of starting treatment
What kind of drug is methotrexate?
Immunosuppressant
What can be done when there is a partial or no response to methotrexate?
Other DMARDs can be added
How are the adverse effects of methotrexate minimised?
The doses required for treatment are much lower, and given once a week
What are the most common side effects of methotrexate therapy in the treatment of RA?
Mucosal ulceration and nausea
What side effects might be seen with chronic administration of methotrexate in RA?
Cytopenias, particularly depression of WBC count, cirrhosis of the liver, and acute pneumonia-like syndrome
What monitoring is required with methotrexate?
Signs of infection
Complete blood count
Liver enzyme tests
What are the serious side effects of methotrexate?
Mucositis Bone marrow suppression Hepatitis Cirrhosis Infection risk Teratogenic abortifactant
What is the oral bioavailability of methotrexate?
Very variable dependant on dose, but when given IV, about 50%
What is the half life of methotrexate?
Dependant on dose, but in high doses, about 8-10 hours
How is methotrexate metabolised?
Undergoes intracellular/hepatic metabolism to polyglutamates
How is methotrexate eliminated?
90% renal, through glomerular active and tubular secretion
What therapeutic DDIs does methotrexate have?
Other immunosuppressants, anti-cancer drugs, and in auto-immune conditions
What adverse DDIs does methotrexate have?
Drugs affecting renal blood flow, renal elimination, and drugs affecting plasma protein binding, phenytoin, tetracyclines, pencillin.
In combination with these, increased risk of myelosupression
What is sulfasalazine made up of?
5-aminosalicylate and sulfapyridine
Describe the absorption of sulfasalazine
It has unique pharmacokinetics in the gut, and travels through the length of the upper GI tract until it reaches the colon. Then, in the colon, bacterialaction causes the breakdown of sulfasalazine into 5-ASA and sulfapyridine.
What is the mechanism of action of sulfasalazine in RA?
Unclear, not to do with COX-2 inhibition.
Appears to inhibit T-cell proliferation and IL-2 production, and may cause T-cell apoptosis. In neutrophils, it reduces chemotaxis and degranulation
What component of sulfasalazine causes ADRs?
Sulfapyridine
What % of patients on sulfapyridine (sulfasalazine) experience ADRs?
10-45%
What are the common ADRs of sulfapyridine (sulfasalazine)?
Nausea, fatigue, headache
What are the serious ADRs of sulfapyridine (sulfasalazine)?
Myelosuppression, hepatitis, allergic rash
Is sulfasalazine safe in pregnancy?
Yes
What are the DDIs with sulfasalazine
Few
What is the onset of action of sulfasalazine treatment in RA?
1-3 months
What are IL-1 and TNF-alpha?
Pro-inflammatory cytokines involved in the pathogenesis of RA
What secretes IL-1 and TNF-alpha?
Synovial macrophages
What happens when synovial macrophages secrete IL-1 and TNF-alpha?
It stimulates synovial cells to proliferate and synthesise collagenase, thereby degrading cartilage, stimulating bone reabsorption, and inhibiting proteoglycan synthesis
What effect do TNF-alpha inhibitors have on RA?
Shown to decrease signs and symptoms of RA, reduce progression of structural damage, and improve physical function
What is the onset of response with TNF-alpha inhibitors in RA?
Within 2 weeks
What are patients receiving TNF-alpha inhibitors at increased risk of?
Tuberculosis, sepsis, fungal opportunistic infections, pancytopenia
What rare but serious ADRs can occur with TNF-alpha inhibitors?
Demyelinating disorders and bone marrow suppression
What conditions should TNF-alpha inhibitors be caused cautiously with?
Heart failure
Why should TNF-alpha inhibitors be caused cautiously with heart failure?
Because they can cause or worsen pre-existing heart failure
Give 3 examples of TNF-alpha inhibitors
Infliximab, adalimumab, rituximab
What is the mechanism of action of infliximab?
It is a monoclonal antibody that binds specifically to human TNF-alpha, and inhibits binding with its receptors
Where is infliximab approved for use?
Patients with RA who have had inadequate response to methotrexate monotherapy
How is infliximab administered?
It is infused IV over at least 2 hours
What is the half life of infliximab?
9.5 days
What are the adverse effects of infliximab
Infusion site reactions, e.g. fever, chills, pruritus, and utricaria
Infections leading to pneumonia, cellulitis, and other conditions
Leukopenia, neutropenia, thrombocytopenia, and pancytopenia
What is the mechanism of action of adalimumab?
A recombinant monoclonal antibody that binds to TNF-alpha, thereby interfering with endogenous TNF-alpha activity by blocking its binding to surface receptors
What are the indications for adalimumab?
Severe RA, either as monotherapy or in combination with methotrexate
How is adalimumab administered?
Subcutaneously weekly, or every other week
What are the adverse effects of adalimumab?
Headache, nausea, agranulocytosis, rash, reaction at injection site, increased risk of infection
What is the role of B lymphocytes in RA?
B lymphocytes can perpetuate the inflammatory process in the synvoium by activating T lymphocytes, producing autoantibodies, and producing pro-inflammatory cytokines such as TNF-alpha and IL-1
What is the mechanism of action of rituximab in RA?
It is a monoclonal antibody directed against the CD20 antigen found on the surface of normal and malignant B lymphocytes, resulting in B-cell depletion
What is the indication for use of rituximab?
In combination with methotrexate, to reduce signs and symptoms of severe RA in adult patients who have inadequate response to one or more TNF-inhibitors
How is rituximab adminstered?
2 IV infusions separated by 2 weeks
What are the adverse effects of rituximab?
Infusion reactions are most common
