Infliximab and Etanercept are two landmark biologic DMARDs that transformed the treatment of autoimmune and inflammatory diseases. Both target TNF-α (tumor necrosis factor alpha)—a central driver of chronic inflammation—but they differ in structure, route of administration, approved indications, and clinical behavior.
This in-depth guide explains what infliximab and etanercept are, how they work, when to use each, dosing schedules, safety concerns, comparisons, and common mistakes, making it ideal for MBBS students, NEET-PG aspirants, clinicians, and informed patients.
What Are Anti-TNF Biologics?
Anti-TNF drugs neutralize Tumor Necrosis Factor alpha, a key cytokine responsible for:
- Synovial inflammation in arthritis
- Intestinal inflammation in IBD
- Skin & joint damage in psoriasis
They are classified as biologic DMARDs, used when conventional drugs (like methotrexate) are inadequate.
Infliximab
What Is Infliximab?
Infliximab is a chimeric monoclonal antibody (mouse + human) that binds both soluble and membrane-bound TNF-α.
Approved Uses
- Rheumatoid Arthritis (with methotrexate)
- Crohn’s Disease
- Ulcerative Colitis
- Ankylosing spondylitis
- Psoriatic arthritis
- Severe plaque psoriasis
Route & Dosing
- IV infusion
- Given at 0, 2, 6 weeks, then every 8 weeks
Key Strengths
- Very effective in IBD
- Rapid induction of remission
- Strong TNF neutralization
Limitations
- Infusion reactions
- Higher immunogenicity (antibody formation)
- Hospital/infusion-center dependent
Etanercept
What Is Etanercept?
Etanercept is a soluble TNF receptor fusion protein that acts as a decoy receptor, binding circulating TNF-α.
Approved Uses
- Rheumatoid arthritis
- Juvenile idiopathic arthritis
- Ankylosing spondylitis
- Psoriatic arthritis
- Plaque psoriasis
Not effective in Crohn’s or UC
Route & Dosing
- Subcutaneous injection
- Once or twice weekly
Key Strengths
- Self-administered at home
- Lower risk of antibody formation
- Fewer infusion-related issues
Limitations
- Ineffective in inflammatory bowel disease
- Requires regular injections
Mechanism of Action
| Feature | Infliximab | Etanercept |
|---|---|---|
| Drug type | Monoclonal antibody | Receptor fusion protein |
| TNF binding | Soluble + membrane TNF | Soluble TNF only |
| Cell apoptosis | Yes | Minimal |
| IBD efficacy | ✅ Yes | ❌ No |
Exam pearl:
Infliximab induces apoptosis of TNF-expressing T-cells → key reason it works in Crohn’s disease.
Infliximab vs Etanercept: High-Yield Comparison
| Feature | Infliximab | Etanercept |
|---|---|---|
| Route | IV infusion | SC injection |
| Dosing frequency | Every 8 weeks (maintenance) | Weekly / twice weekly |
| Use in Crohn’s / UC | ✅ Yes | ❌ No |
| Immunogenicity | Higher | Lower |
| Infusion reactions | Common | None |
| Convenience | Moderate | High |
Side Effects of Anti-TNF Therapy
Common
- Injection/infusion site reactions
- Upper respiratory infections
- Headache, fatigue
Serious (Class Effects)
- Tuberculosis reactivation
- Opportunistic infections
- Heart failure worsening
- Demyelinating disease
- Increased malignancy risk (rare)
Pre-Treatment Screening
Before starting any anti-TNF agent:
1. TB screening (Mantoux / IGRA)Contraindications
- Active infections
- Latent TB (until treated)
- Moderate to severe heart failure
- Demyelinating disorders
- Recent live vaccines
Common Mistakes & How to Avoid Them
❌ Starting biologics without TB screening → Always screen first
❌ Using etanercept in Crohn’s → Ineffective choice
❌ Stopping methotrexate with infliximab → ↑ antibodies
❌ Ignoring infections → Hold drug during active infection
FAQs
Are infliximab and etanercept chemotherapy?
No—they are biologic immunomodulators, not cytotoxic drugs.
Which is better for rheumatoid arthritis?
Both are effective; etanercept is more convenient, infliximab is often combined with MTX.
Why is etanercept not used in Crohn’s disease?
It does not induce T-cell apoptosis in gut inflammation.
Can these drugs cure autoimmune disease?
No—but they can induce remission and prevent damage.
Are biosimilars available?
Yes—biosimilars of both drugs are widely used.
