850- Transplant lecture Flashcards
Indications for Organ Transplant
- Kidney: Diabetes, hypertension, lupus PCKD
- Liver: Alcoholic cirrhosis, NASH, HBV, HCV, HCC, APAP toxicity
- Pancreas: Diabetes, Congenital Abnormalities
- Heart: Ischemic heart disease, congenital abnormalities, idiopathic cardiomyopathy, valvular diseases
- Lung: CF, pulmonary HTN, pulmonary fibrosis COPD, emphysema
Goals of Immunosuppression:
- Prevent rejection
- Avoid complications with high dose immunosuppressants
- Patient and graft survival
- Patient adherence
Potency of Immunosuppression:
Less Immunosuppressive (lower number) 1. Belatacept 2. Sirolimus/Everolimus 3. Azathioprine 4. Mycophenolate 5. Cyclosporine 6. Tacrolimus 7. Basiliximab 8. Thymoglobulin 9. Alemtuzumab More Immunosuppressive (higher number)
Induction Therapy Goal:
- Prevent early acute allograft rejection using intense, prophylactic immunosuppression therapy
- This produces profound deficiency on T cells and/or B cells that can last months
Induction Therapy Drugs:
- Basiliximab
- Antithymocyte globulin
- Alemtuzumab
Basliximab (Simulect®)
CD25
• Mechanism of action:
–Blocks T‐cell proliferation via Interleukin‐2 (IL‐2) reception antagonism (anti‐CD25 antibodies)
• Used in lowest immunologic risk patients
• Decreased infection rates when compared to
other agents
• Does not lead to sustained depletion of lymphocytes and related CD4 helper T cells
Antithymocyte Globulin (Thymoglobulin®)
• Mechanism of Action:
–Binds to T‐cell surface antigens leading to the
elimination of T‐cells
• Used in moderate to high immunologic risk
• Increased risk for CMV and BKV
• PJP and other invasive fungal pathogens have been associated with thymoglobulin
Alemtuzumab (Campath®)
CD52 & “AIDS”
• Mechanism of Action:
– Binds to CD52 on T‐cells, B‐cells, NK cells, and monocytes/macrophages causing complement activation and antibody‐dependent cellular toxicity
• “AIDS” in a bottle, results to pan T‐cell depletion
• Used as steroid sparing induction
• CD4/CD8 counts nadir at 4 weeks, 1+ years for recovery
• Associated with many opportunistic infections
Maintenance Therapy Goal:
- Prevent allograft rejection
- Maintain an adequate balance of graft function, adverse effects, and prevention of infection
(Lifelong immunosuppression)
Maintenance Therapy Drugs:
- Corticosteroids
- Calcineurin inhibitors
- Antimetabolites
- mTOR inhibitors
Corticosteroids
• OLDEST immunosuppressive agent used in transplantation
• Mechanism of Action:
–Inhibition of cytokine gene expression
–Modification of lymphocyte distribution and function
–Anti‐inflammatory effects
• Dosing:
–Prednisone 5‐10 mg/day (maintenance dose)
(Higher doses are used for induction & rejection therapy)
Corticosteroids: Adverse Effects
• Short Term
- Mood alterations
- Hyperglycemia
- Hypertension
- Increased appetite
- Insomnia
- Mood changes
- Acne
- Leukocytosis
Corticosteroids: Adverse Effects
• Long Term
- Osteoporosis
- Chronic adrenal insufficiency
- Ulcerative esophagitis
- Hirsutism
- Pancreatitis
- Amenorrhea
- Diabetes mellitus
Calcineurin Inhibitors Drugs:
- Tacrolimus (Prograf, Hecoria, and Astagraf XL)
* Cyclosporine (Neoral, Gengraf, and Sandimmune)
Tacrolimus
T-cell activity
• Products:
– Prograf® (capsules, IV)
– Generic tacrolimus (capsules, IV)
– Astagraf XL® (extended release capsules)
– Envarsus XR® (extended release capsules)
– Compounded oral suspension
Also called FK506
• MOA:
– Inhibits T‐cell activity through inhibition of IL‐2 production
Tacrolimus: PK & PD
• Absorption: Incomplete and variable
– Best absorbed on an empty stomach
– Bioavailability: 7 ‐ 32%
• Distribution: highly lipophilic
– 99% protein bound (albumin and α1‐acid glycoprotein)
• Metabolism: extensive CYP3A4, p‐glycoprotein
– Half life:
~ 9 hours (immediate release)
~ 34 hours (extended release)
Tacrolimus: Dosing
- Dosing:
– Immediate Release: 0.05‐0.1mg/kg/day in divided doses
◦ Generally ~1‐4 mg BID
– Extended Release: 0.1‐0.2 mg/kg/day one time daily - Dose adjusted based on trough concentrations and renal function
– Goal concentration varies:
◦ Time after transplant, type of organ transplanted, infection - Therapeutic range 5 – 15 ng/mL
Tacrolimus: Interactions
- Primarily through hepatic metabolism CYP3A4: inhibition or induction
– Examples:
◦ Ketoconazole, diltiazem, and grapefruit juice inhibit CYP3A4
◦ Phenytoin and rifampin induce CYP3A4 - P‐glycoprotein substrate
- Antacids
–Physical interaction –» reduced absorption
–Separate by at least 2 hours
Tacrolimus: Adverse Effects
*more common in tacrolimus than cyclosporine
- Hypertension
- Diarrhea
- Nephrotoxicity
- Headache
- Hepatotoxicity
- Hyperglycemia*
- Pruritis
- Hyperkalemia
- Hypomagnesemia
- Infection
- Neurotoxicity (tremors)
- Alopecia
Cyclosporine
T-cell proliferation
1. Products: –Modified microemulsion formulation • Neoral® or Gengraf® –Unmodified formulation • Sandimmune® –Sandimmune® & Neoral®/Gengraf® are not equivalent
- MOA:
–Inhibits T‐cell proliferation through inhibition of IL‐2 production