1. Clinical Overview
Iguratimod is a novel, orally administered small-molecule disease-modifying anti-rheumatic drug (DMARD) used primarily for the treatment of rheumatoid arthritis (RA). It is a synthetic compound with a unique dual mechanism of action, inhibiting both the production of inflammatory cytokines (like IL-6, IL-8, TNF-α) and immunoglobulin production by B cells. It is indicated for patients with active RA who have had an inadequate response to conventional DMARDs like methotrexate.
| Onset | Duration | Bioavailability |
|---|---|---|
| Clinical improvement in symptoms (e.g., tender/swollen joint count) is typically observed within 4 to 8 weeks of continuous therapy. | The therapeutic effect is sustained with continued daily dosing. The drug's effects are not immediate and require consistent administration. | Approximately 57-60% in the fasting state. Food, especially a high-fat meal, can significantly reduce absorption. |
2. Mechanism of Action
Iguratimod exerts its anti-inflammatory and immunomodulatory effects through a dual mechanism: 1) Inhibition of pro-inflammatory cytokine production (notably IL-6, IL-8, TNF-α, and MMPs) from synovial fibroblasts and macrophages via suppression of nuclear factor-kappa B (NF-κB) activation. 2) Inhibition of immunoglobulin (IgG, IgM) production by activated B-lymphocytes, potentially by suppressing the activity of transcription factors like NF-AT.
3. Indications & Uses
- Active Rheumatoid Arthritis (moderate to severe) in adults
- Rheumatoid Arthritis with inadequate response to Methotrexate (MTX) or other conventional DMARDs
4. Dosage & Administration
Adult Dosage: 25 mg orally twice daily (total 50 mg/day). After achieving adequate response, some guidelines suggest maintenance with 25 mg once daily, but the standard is twice daily. Must be taken on an empty stomach.
Administration: Swallow the tablet whole with a glass of water. Take on an empty stomach, at least 1 hour before or 2 hours after a meal. Do not crush or chew. Dosing should be consistent, at approximately the same time(s) each day.
5. Side Effects
Common side effects may include:
- Upper abdominal pain/discomfort
- Dyspepsia
- Nausea
- Elevated liver enzymes (ALT, AST)
- Headache
- Rash
- Leukopenia (mild)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Methotrexate | Increased risk of hepatotoxicity and bone marrow suppression. Monitor LFTs and CBC closely. | Major |
| Other Hepatotoxic Drugs (e.g., Paracetamol high dose, Azathioprine, Leflunomide) | Additive risk of liver damage. Requires enhanced monitoring. | Major |
| CYP2C19 Inhibitors (e.g., Omeprazole, Fluconazole, Fluvoxamine) | May increase iguratimod plasma concentration, increasing toxicity risk. | Moderate |
| CYP2C19 Inducers (e.g., Rifampicin, Carbamazepine) | May decrease iguratimod plasma concentration, reducing efficacy. | Moderate |
| Warfarin | Potential for increased INR and bleeding risk due to protein binding displacement and possible effects on coagulation. Monitor INR frequently. | Major |
| Live Vaccines (e.g., MMR, Varicella, Yellow Fever) | Increased risk of vaccine-induced infection. Avoid vaccination during therapy. | Major |
7. Patient Counselling
- DO take the medicine exactly as prescribed, on an empty stomach.
- DO keep all follow-up appointments for blood tests (LFT, CBC, Creatinine).
- DO inform all your doctors and dentists you are taking this medicine before any procedure.
- DO practice good hygiene to avoid infections.
- DONT take the medicine with food or immediately after a meal.
- DONT crush, break, or chew the tablet.
- DONT start any new medicine (including OTC, herbal) without consulting your doctor.
- DONT receive live vaccines while on this therapy.
8. Toxicology & Storage
Overdose: Limited data. Expected symptoms may include severe nausea, vomiting, abdominal pain, elevated liver enzymes, leukopenia, and dizziness.
Storage: Store below 30°C. Protect from light and moisture. Keep the bottle tightly closed. Keep out of reach of children. Do not use after the expiry date printed on the label.