Immunosuppressive drugs are essential in managing various medical conditions, particularly in preventing organ transplant rejection and treating autoimmune diseases. They can be classified into five main groups:

1. Glucocorticoids: These are steroid hormones that reduce inflammation and suppress the immune response. They work by inhibiting the production of inflammatory cytokines and reducing the proliferation of immune cells. Common glucocorticoids include prednisone and dexamethasone. Their effects include:

   • Mechanism of Action: Glucocorticoids inhibit the expression of genes coding for pro-inflammatory cytokines (e.g., IL-1, IL-2, TNF-α).

   • Clinical Uses: They are used in conditions like rheumatoid arthritis, lupus, and to prevent transplant rejection.

   • Side Effects: Long-term use can lead to osteoporosis, weight gain, diabetes, and increased risk of infections.

2. Cytostatic Drugs: These agents inhibit cell division and are often used in cancer treatment as well as in autoimmune diseases. They include:

   • Examples: Cyclophosphamide, azathioprine, and methotrexate.

   • Mechanism of Action: They interfere with DNA synthesis and cell proliferation, particularly affecting rapidly dividing cells.

   • Clinical Uses: Effective in treating cancers, systemic lupus erythematosus, and other autoimmune disorders.

   • Side Effects: Can cause bone marrow suppression, leading to increased risk of infections and anemia.

3. Antibodies: This group includes monoclonal and polyclonal antibodies that target specific components of the immune system.

   • Types:

     • Monoclonal Antibodies: Such as basiliximab and daclizumab, which target the IL-2 receptor to prevent T-cell activation.
     • Polyclonal Antibodies: These are derived from multiple B-cell clones and can broadly suppress immune responses.

   • Clinical Uses: Used in organ transplantation and to treat autoimmune diseases.

   • Side Effects: Risk of infections and allergic reactions due to immune suppression.

4. Drugs Acting on Immunophilins: These drugs modulate immune responses by binding to immunophilins, which are proteins that assist in the folding of other proteins.

   • Examples: Cyclosporine and tacrolimus.

   • Mechanism of Action: They inhibit calcineurin, a phosphatase involved in T-cell activation, thereby reducing the production of IL-2.

   • Clinical Uses: Primarily used in organ transplantation to prevent rejection.

   • Side Effects: Nephrotoxicity, hypertension, and increased risk of infections.

5. Other Drugs: This category includes various agents that do not fit neatly into the other classifications but still have immunosuppressive effects.

   • Examples: Mycophenolate mofetil and sirolimus.

   • Mechanism of Action: Mycophenolate inhibits lymphocyte proliferation by blocking purine synthesis, while sirolimus inhibits mTOR, affecting T-cell activation and proliferation.

   • Clinical Uses: Used in transplant patients and in some autoimmune diseases.

   • Side Effects: Gastrointestinal disturbances, increased risk of infections, and potential for malignancies.

Erythromycin

used for people who have an allergy to penicillins. For respiratory tract infections, it has better coverage of atypical organisms, including  mycoplasma. It is also used to treat outbreaks of chlamydia, syphilis, and gonorrhea.

Erythromycin is produced from a strain of the actinomyces Saccaropolyspora erythraea, formerly known as Streptomyces erythraeus.

Methicillin

Methicillin is an antibiotic related to penicillin and other beta-lactam containing antibiotics. It is often used to treat infections caused by bacteria carrying an antibiotic resistance, e.g., staphylococci. As methicillin is deactivated by gastric acid, it has to be administered by injection.

Uses Methicillin serves a purpose in the laboratory to determine antibiotic sensitivity in microbiological culture.

Itraconazole:

The drug may be given orally or intravenously.

Immunosuppressive antibodies can be classified mainly into monoclonal and polyclonal antibodies, targeting specific components of the immune system.

1. Monoclonal Antibodies:

   • Basiliximab: Targets the IL-2 receptor on T cells, inhibiting T-cell activation. It is FDA approved for use in renal transplantation to prevent acute rejection.

   • Alemtuzumab: Targets CD52, a protein found on the surface of mature lymphocytes. It is used for treating chronic lymphocytic leukemia and as an induction agent in kidney transplantation.

   • Rituximab: Targets CD20 on B cells, leading to B-cell depletion. It is used in various conditions, including non-Hodgkin lymphoma and rheumatoid arthritis.

   • Daclizumab: Targets the IL-2 receptor (CD25) and is used in renal transplantation to prevent acute rejection.

   • Eculizumab: Targets complement component C5, inhibiting the complement cascade. It is used in conditions like paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome.

2. Polyclonal Antibodies:

   • Rabbit Antithymocyte Globulin (rATG): A polyclonal antibody that targets multiple T-cell surface markers, leading to T-cell depletion. It is used as an induction agent in kidney transplantation and for treating acute rejection.

   • Equine Antithymocyte Globulin (eATG): Similar to rATG, it targets T cells and is used in transplantation settings.

3. Mechanisms of Action:

   • Depletion of Immune Cells: Many antibodies work by depleting specific immune cell populations (e.g., T cells or B cells) to reduce the immune response against transplanted organs or in autoimmune diseases.

   • Blocking Activation Signals: Some antibodies block key receptors involved in T-cell activation, preventing the immune response from being initiated.

   • Inhibition of Complement Activation: Antibodies like eculizumab inhibit the complement system, which can contribute to tissue damage in antibody-mediated rejection.

4. Clinical Applications:

   • Organ Transplantation: Antibodies are commonly used to prevent rejection in kidney, liver, and heart transplants.

   • Autoimmune Diseases: They are also used in treating conditions like rheumatoid arthritis, lupus, and multiple sclerosis.

5. Potential Side Effects:

   • Infections: Due to immune suppression, patients are at increased risk of infections.
   • Allergic Reactions: Some patients may experience allergic reactions to antibody therapies.
   • Infusion Reactions: These can occur during the administration of monoclonal antibodies, leading to symptoms like fever, chills, and hypotension.

Fourth Generation:

These are extended spectrum antibiotics. They are resistant to beta lactamases.

Cefipime