Rheumatic Disorders (Med Chem) - Block 1 Flashcards
What is the gold standard for DMARDs?
Methotrexate
What are examples of conventional syntheitic DMARDs?
- Methotrexate (MTX)
- Leflunomide (LEF)
- Sulfasalazine (SSZ)
- Hydroxycholorquine (HCQ)
What are examples of targeted synthetic DMARDs?
- Tofacitinib
- Upadacitinib
- Baricitinib
How components are inhibited by methotrexate?
Disrupts cell division and increases anti-inflammatory effects by adenosine by inhibiting:
1. Dihydrofolic acid reductase (DHFR)
2. Thymidylate synthetase (TYMS)
3. Amino-imidazolecarboxamide ribonecleotide transformylase (AICART)
Describe the MOA of methotrexate?
- Inhibits TYMS blocking thymine production
- Inhibits DHFR that disrupts DNA methylation and methionine stores
- Inhibits AICART increasing adenosine
* Increased AICAR inhibits ADA (adenine deaminase) and AMP deaminase) blocking the production of guanine (i.e. purine synthesis)
Processes cause disruption in purine and S phase
How is Methotrexate eliminated? And how does it affect concomitant therapies
OAT1, OAT3, MRP2/4
NSAIDs reduce glomerular filtration and inhibit OAT1/3 and MRP2/4 reducing MTX clearance
Methotrexate
CI, ADR
CI: teratogenic, hepatic and renal impairment
ADR: GI toxicity (ulcerative stomatits and diarrhea), hepatotoxicity (fibrosis and cirrhosis), malignant lymphoma
Describe the MOA of Leflunomide?
Teriflunomide (active) inhibits dihyrooradate dehydrogenase (DHODH)
What is the importance for DHODH?
Rate limiting step of pyrimidine synthesis arresting B cell and T cell proliferation
Describe the difference between leflunomide and methotrexate?
Leflunomide
ADR, CI, BBW
ADR: D/N/V, rashes, alopecia, HTN
CI: liver impairment, pregnancy
BBW: fetal toxicity, hepatotoxicity
MOA of sulfasalazine? What are the metabolites?
Prodrug that is metabolized by colonic bacteria and produce active metabolites:
1. Sulfapyridine: bacterial DNA synthesis inhibitor
2. 5-ASA: NSAID concnetrated in the synovial fluid
Sulfasalazine
Brand, CI, ADR
Azulfidine
CI: Hemolysis in G6PD def (hemolytic anemia), sulfa allergy, salicylate allergy, different types of anemia
ADR: GI distress, photosensitivity, oligospermia, alopecia, orange-yellow urine or skin, reduces absorption of folic acid and digoxin
MOA of Hydroxychloroquine
- Blocks the activation of antigen presenting cells
- Prevents acidification of the lysosome and antigen processing -> blocking antigen presentation
- Prevents endosomal TLR signaling (7,8,9) and subsequent cytokine production
Hydroxychloroquine
Brand, DI, ADR
Plaquenil
DI: Digoxin, antacids
ADR: Ocular toxicity, cardiac, ear disorders, GI and skin effects
Describe the components of the JAK stat signaling pathway?
- Tyrosine kinase receptor that acts as a cytokine and GFR on immune cells
- Cytokine binds to JAK-R
- JAK phosphorylates STAT which serves as a transcription factor
- STAT activates transcription and production of cytokines
Tofacitinib
Brand, MOA, BBW, ADR, CI
Xeljanz
MOA: 1st generation Pan Janus kinase (JAK) inhibitor (JAKi) that blocks JAKs 1-3
* Inhibits cytokine and growth factor induced JAK-STAT pathway signaling
BBW: TB, infection, malignancies, MACE, thrombosis
ADR: Increase in TC, bone marrow suppression, GI perforations, Infection
CI: Should not be combined with potent immunosuppressive agents or bDMARDs
* Avoid live vaccines
Baricitinib
Brand, MOA, BBW, ADR, CI
Oluminant
MOA: Inhibits cytokine and growth factor induced by JAK1 and JAK2 signaling
BBW: TB, infection, malignancies, MACE, thrombosis
ADR: Increase in TC, bone marrow suppression, GI perforations, Infection
CI: Should not be combined with potent immunosuppressive agents or bDMARDs
* Avoid live vaccines
Upadacitinib
Brand, MOA, BBW, ADR, CI
Rinvoq
MOA: JAK1 selective inhibitor
* Inhibits cytokine induced JAK1 signaling by blocking IL6 and IFN
BBW: TB, infection, malignancies, MACE, thrombosis
ADR: Increase in TC, bone marrow suppression, GI perforations, Infection
CI: Should not be combined with potent immunosuppressive agents or bDMARDs
* Avoid live vaccines
What is a chimeric mAb?
4/12 domains are murine (2-VL and 2VH)
What is humanized mAb?
murine CDRs grafted into human mAb (IgG)
What is fully human?
the protein sequence is fully human
What is pegylated fab fragment?
polyethylene glycol is attached to the Fab portion of an IgG antibody
What are receptor Fc fusion?
functional receptor protein joined to the Fc portion of IgG
What more humanized the more/less immunogenic the mAb
Less
What are the disadvantages of having more immunogenicity?
Can lead to hypersensitivity producing antibodies against the therapeutic antibody
Prefix for chimeric?
Ximab
Prefix for human?
Umab
Prefix for humanized?
zumab
Prefix for mouse?
omab
Prefix for cept?
Fab protion has been replaced with receptor protein sequence
What are biosimilars?
same aa sequence as original mAb but produced from a different clone and can have different glycosylations
What are the functions of monoclonal antibodies?
mAbs are able to bind to their specific target and induce an effector function:
1. Neutralization/Blocking
1. Complement-Mediated Cytotoxicity (CDC)
1. Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)
1. Antibody-Dependent Cell-Mediated Phagocytosis (ADCP)
What occurs during Antibody Dependent Cell-Mediated Cytotoxicity (ADCC)?
- Antibodies bind to membrane-surface antigens on the target cell
- Cells expressing Fc receptors recognize bound antibodies
- Crosslinking of Fc receptors triggers degranulation into lytic synapse
- Target cell dies by apoptosis requiring Fc region