Vedolizumab is an integrin receptor antagonist that works by selectively blocking the interaction between α4β7 integrin on immune cells (e.g., T-lymphocytes) and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) on the endothelial cells of the gastrointestinal tract. This interaction is critical for the migration of inflammatory immune cells into the gut. By inhibiting this process, vedolizumab:

1. Reduces Inflammation: Prevents the infiltration of pro-inflammatory immune cells into the gastrointestinal mucosa.
2. Targets Gut-Specific Immunity: Unlike other immunosuppressive agents, vedolizumab selectively acts on the gut, minimizing systemic immunosuppression and reducing the risk of systemic side effects.

Vedolizumab is indicated for the treatment of:

1. Ulcerative Colitis:
   • Moderate to severe active ulcerative colitis in adults who have had an inadequate response, lost response, or were intolerant to conventional therapies (e.g., corticosteroids, immunomodulators, or TNF inhibitors).
2. Crohn's Disease:
   • Moderate to severe active Crohn's disease in adults who have had an inadequate response, lost response, or were intolerant to conventional therapies or TNF inhibitors.

Vedolizumab is administered as an intravenous (IV) infusion. The dosing regimen is as follows:

1. Induction Phase:
   • 300 mg administered at weeks 0, 2, and 6.
2. Maintenance Phase:
   • 300 mg every 8 weeks.
3. Special Populations:
   • Elderly: No dose adjustment is required, but caution is advised due to increased susceptibility to infections.
   • Renal/Hepatic Impairment: No dose adjustment is necessary.
   • Pediatric Use: Safety and efficacy in children have not been established.

Vedolizumab is generally well-tolerated, but some side effects may occur. These include:

1. Common Side Effects:
   • Headache
   • Nausea
   • Upper respiratory tract infections
   • Nasopharyngitis
   • Arthralgia (joint pain)
2. Serious Side Effects:
   • Infections: Increased risk of infections, including nasopharyngitis, urinary tract infections, and gastroenteritis.
   • Hypersensitivity Reactions: Infusion-related reactions (e.g., rash, pruritus, anaphylaxis).

Liver Injury: Rare cases of hepatotoxicity have been reported

1. Contraindications:
   • Hypersensitivity to vedolizumab or any of its excipients.
   • Active severe infections (e.g., tuberculosis, sepsis).
2. Warnings:
   • Infections: Monitor for signs of infection during and after treatment. Discontinue vedolizumab in patients with serious infections.
   • Progressive Multifocal Leukoencephalopathy (PML): Although rare, PML has been reported with other integrin receptor antagonists. Monitor for neurological symptoms.
   • Vaccinations: Ensure patients are up-to-date with vaccinations before starting vedolizumab. Avoid live vaccines during treatment.
3. Monitoring:
   • Signs and symptoms of infection.
   • Liver function tests (if hepatotoxicity is suspected).
   • Neurological symptoms (e.g., weakness, vision changes, cognitive disturbances).

Vedolizumab has a low potential for drug interactions due to its gut-specific mechanism of action. However, the following should be considered:

1. Immunosuppressants: Concurrent use with other immunosuppressive agents (e.g., corticosteroids, azathioprine) may increase the risk of infections.
2. Live Vaccines: Avoid administering live vaccines during vedolizumab therapy due to the risk of vaccine-induced infections.

TNF Inhibitors: Concurrent use with TNF inhibitors is not recommended due to an increased risk of infections and lack of evidence for added benefit

Vedolizumab is a biologic medication and is not available in generic form. It is marketed under the brand name Entyvio