1. Clinical Overview
Epalrestat is a potent, competitive, and reversible inhibitor of the enzyme aldose reductase. It is the first and only aldose reductase inhibitor (ARI) approved and widely used in India for the treatment of diabetic peripheral neuropathy (DPN). It acts by inhibiting the polyol pathway, thereby reducing the accumulation of sorbitol in nerve cells, which is a key factor in the pathogenesis of diabetic neuropathy. It is indicated for the improvement of subjective neuropathy symptoms and objective nerve function parameters in patients with diabetic neuropathy.
| Onset | Duration | Bioavailability |
|---|---|---|
| Subjective symptom relief may be noticed within 2-4 weeks. Objective improvement in nerve conduction velocity may take 3-6 months of continuous therapy. | Approximately 24 hours, supporting once-daily dosing. | Approximately 75-80% after oral administration. |
2. Mechanism of Action
Epalrestat selectively and competitively inhibits the enzyme aldose reductase (AR). Under hyperglycemic conditions, excess intracellular glucose is shunted into the polyol pathway where aldose reductase converts it to sorbitol using NADPH. Sorbitol is then converted to fructose by sorbitol dehydrogenase. This process leads to intracellular accumulation of sorbitol, depletion of myo-inositol, and reduction in Na+/K+ ATPase activity. Epalrestat's inhibition of AR prevents sorbitol accumulation, thereby helping to restore nerve conduction velocity, reduce oxidative stress, and improve microvascular blood flow in nerves.
3. Indications & Uses
- Symptomatic Diabetic Peripheral Neuropathy (DPN)
- Improvement of nerve function in diabetic neuropathy
4. Dosage & Administration
Adult Dosage: 50 mg three times daily (TDS), orally, before meals. Standard total daily dose is 150 mg.
Administration: Take capsule/tablet orally with a glass of water, preferably before meals. Do not crush or chew. Adhere strictly to the TDS schedule for consistent enzyme inhibition.
5. Side Effects
Common side effects may include:
- Nausea
- Abdominal discomfort
- Diarrhea
- Headache
- Skin rash/itching
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Tolbutamide | Epalrestat may potentiate the hypoglycemic effect. Mechanism may involve protein binding displacement. | Moderate |
| Warfarin | Potential increase in anticoagulant effect due to protein binding displacement. Monitor INR closely. | Moderate |
| Strong UGT Inducers (e.g., Rifampicin) | May increase metabolism of Epalrestat, reducing its plasma concentration and efficacy. | Moderate |
| Other Highly Protein-Bound Drugs (e.g., Phenytoin, NSAIDs) | Theoretical potential for mutual displacement. Clinical significance unknown. | Low |
7. Patient Counselling
- DO take the medicine exactly as prescribed, three times daily before meals.
- DO continue taking your anti-diabetic medications (insulin/oral) as directed. This drug is an adjunct, not a substitute.
- DO attend regular follow-ups with your doctor for neuropathy assessment and liver function tests.
- DONT stop the medication abruptly without consulting your doctor, even if symptoms improve.
- DONT crush or chew the capsule/tablet.
8. Toxicology & Storage
Overdose: Limited data. Symptoms may include exacerbation of known adverse effects: severe nausea, vomiting, diarrhea, dizziness, and potential liver enzyme elevation.
Storage: Store below 30°C. Protect from light and moisture. Keep in the original packaging. Keep out of reach of children.