Immunosuppressive Drugs Flashcards
- Primitive, does not require priming
- Most active early in an immune response
- Major effectors: Complement
1. Granulocytes
2. Monocytes/macrophage
3. NK cells
4. Mast cells, basophils
Innate-natural
- Antigen-specific, depends on Antigen exposure or priming
- Progressively dominant over time
- Major effectors:
1. B lymphocytes -> Antibody
2. T lymphocytes -> helper, cytolytic and regulatory (suppressor cells) - Important in the normal immune response to infection and tumors
- Also mediate transplant rejection and autoimmunity
- Modulation of immune response: immunosuppression
• Tolerance
• Immunostimulation
Adaptive-learned
4 Major Classes of Immunosuppressives
- Glucocorticoids
- Calcineurin inhibitors
- Antiproliferative and antimetabolic agents
- Antibodies
“Holy Grail” of Immunomodulation
Induction and maintenance of immune tolerance –> active state of Ag-specific non-responsiveness (the body will not reject organs transplanted to the body)
- Dampen the immune response in organ transplantation and autoimmune disease (the body attacks its own system)
- Tx requires lifelong use
- Non-specifically suppress the entire immune system —> patients exposed to higher risks of infection and cancer
Immunosuppression
General approach to Organ Transplantation Tx
5 general principles:
- Carefully prepare the patient and select the best available ABO blood type–compatible HLA match for organ donation
o Sometimes not followed because of lack of donors. The patients are just bombarded with immunosuppressives and have a higher risk of organ rejection. - Employ multitier immunosuppressive therapy; simultaneously use several agents, each of which is directed at a different molecular target within the allograft response. Synergistic effects permit the use of various agents at relatively low doses, thereby limiting specific toxicities while maximizing the immunosuppressive effect
> immunosuppression required to gain early engraftment/Tx established rejection than to maintain long term immunosuppression - Employ intensive induction and lower-dose maintenance drug protocols; greater immunosuppression is required to gain early engraftment or to treat established rejection than to maintain long-term immunosuppression. The early high risk of acute rejection is replaced over time by the increased risk of the medications’ side effects, necessitating a slow reduction of maintenance immunosuppressive drugs.
- Careful investigation of each episode of transplant dysfunction is required, including evaluation for recurrence of the disease, rejection, drug toxicity, and infection (keeping in mind that these various problems can and often do coexist).
- Reduce dosage or withdraw a drug if its toxicity exceeds its benefit. Ideal before transplantation to have HLA typing
Used to delay the use of calcineurin inhibitors or to intensify initial immunosuppressive Tx in patients at high risk of rejection
Biological Induction Therapy
- Repeat transplants
- Broadly presensitized patients
- African-Americans
- Pediatric patients
- Repeat transplants
- Broadly presensitized patients
- African-Americans
- Pediatric patients
Biological Induction Therapy
- Repeat transplants
- Broadly presensitized patients
- African-Americans
- Pediatric patients
Biological Induction Therapy
Biological Induction Therapy has 2 groups:
- Depleting agents
- Immune modulators
MOA: Deplete the recipient’s CD3+ cells at the time of transplantation and Ag presentation
Depleting agents
a. Lymphocyte immune globulin
b. ATG (Antithymocyte globulin) – most commonly used
c. Muromonab –CD3 mAb
d. Deplete the recipient’s CD3+ cells at the time of transplantation and Ag presentation
Depleting agents
MOA: Block IL-2-mediated T-cell activation by binding to α chain of IL-2R (CD25)
Immune modulators
Anti-IL-2RmAbs
Block IL-2-mediated T-cell activation by binding to α chain of IL-2R
Immune modulators
- Multiple drugs used simultaneously
- Calcineurin inhibitor, glucocorticoids, mycophenolate (purine metabolism inhibitor) – each directed at a discrete step in T-cell activation
Maintenance Immunotherapy
- Agents directed against activated T cells
- Glucocorticoids in high doses (pulse therapy)
- Polyclonal antilymphocyte Ab
- Muromonab-CD3
Therapy for Established Rejection
What is the main glucocorticoid?
Cortisol (hydrocortisone)
- Alterations in carbohydrate, protein, and lipid metabolism
- Maintenance of fluid and electrolyte balance
- Preservation of normal fxn of:
o CVS
o Kidney
o Skeletal Muscle
o Endocrine
o Nervous - Gives organisms the capacity to resist stressful circumstances
o pts. with hypercortisolism - more prone to infection
PHYSIOLOGIC FUNCTIONS
Immunosuppressive actions
- 1 of Major pharmacologic uses
- Immune mediators associated w/ inflammatory response
- dec vascular tone –> lead to CVS collapse if unopposed by adrenal corticosteroids CHO andrenal corticosteroids
Stimulate liver to form glucose from amino acids and glycerol and store glucose as liver glycogen
CHO and CHON Metabolism
o Diminish glucose utilization
o Increase CHON breakdown and synthesis of glutamine
o Activate lipolysis
o Provide amino acids and glycerol for gluconeogenesis
o Increase blood glucose levels
*Steroids can cause hyperglycemia
CHO and CHON metabolism: Periphery
Redistribution of body fat in setting of endogenous or
pharmacologically induced hypercortism
o Buffalo hump
o Moon facies
o Supraclavicular a rea
o Loss of fat in extremities
- Increase in FFA after glucocorticoid administration
Lipid Metabolism
Aldosterone
Electrolyte and Water Balance
- Mineralocorticoid – induced changes in renal Na+
- Enhance vascular reactivity to other vasoactive substances
CVS
Excessive amounts-impair muscle fxn (skeletal muscle wasting)
o Steroid myopathy
Skeletal Muscle
Indirect effects
o Maintenance of BP, plasma glucose conc., electrolyte conc.
o Effects on mood, behavior and brain excitability
CNS
- Profoundly alter the immune response of lymphocytes
- MOA: lyse and induce the redistribution of lymphocytes
- Rapid, transient decrease in peripheral blood lymphocyte counts
- Little effect on humoral immunity
Absorption, Transport, Metabolism, and Excretion
Orally effective
After absorption , >=90% in plasma is reversibly bound to protein
Anti-inflammatory and Immunosuppressive actions
Absorbed systemically from sites of local administration
o Synovial spaces – injection
o Conjunctival sac – eye drops
o Skin -creams and ointments for inflammatory reactions
o Respiratory tract – as inhalers