Rheumatoid arthritis Flashcards
How does MTX cause bone marrow suppression and GI disturbances?
MTX inhibits dihydrofolate reductase (DHFR), reducing levels of tetrahydrofolate and thus synthesis of purines and pyrimidines. This inhibition leads to decrease in production of DNA, RNA & certain AAs, ultimately disrupting growth and pro-life of rapidly divings cells such as those found in bone marrow and walls of GIT.
Clinical presentation of RA
- Pain
- Swelling
- Redness and warm
4. Early morning stiffness >30 min
5. Symmetrical polyarthritis
Laboratory findings 1
Autoantibodies
- Rheumatoid factor RF +(ve)
- Anti citrullinated peptide antibodies ACPA , anti-CCP assays (+ve)
Laboratory findings 2
ESR increase
CRP increase
Laboratory findings 3
Hg decrease
Platelets increase
WBC increase
Diagnosis of RA
At least 4 of:
1. Early morning stiffness >1 hour >6 weeks
2. Swelling of >3 joints >6 weeks
4. Swelling of wrist/MCP/PIP joints >6 weeks
5. Rheumatoid nodules
6. +ve RF &/ anti-CCP tests
7. Radiographic changes
Drugs used in RA
- NSAIDs
- Glucocorticoids
- DMARDs
Drug class of MTX
csDMARDs
Drug class of Adalimumab
bDMARDs
Drug class of Tofacitinib
tsDMARDS
Drug class of Infliximab
bDMARDs
Drug class of Etanercept
bDMARDs
Drug class of Golimumab
bDMARDs
Drug class of Anakinra
bDMARDs (not available in SG)
Drug class of Rituximab
bDMARDs
Drug class of Abatacept
bDMARDs (not available in SG)
1st line treatment of RA
MTX monotherapy
Short term low-dose GC can be added when initiating
Dose of MTX
Initiation : 7.5mg once weekly
2.5-5mg/week increment every 4-12 weeks
Target: 15mg/week
What needs to be co-prescribed with MTX? Why?
Folic acid 5mg/week
Rescue therapy: Folic acid, a synthetic form of the naturally occuring vitamin B9, helps prevent MTX-induced side effects by counteracting the reduced level of tetrahydrofolate.
Dose adjustment of MTX
CrCl<50ml/min: 50%
CrCl<30ml/min: AVOID