1. Clinical Overview
Hyaluronidase (1%) is a sterile, purified, lyophilized preparation of the enzyme hyaluronidase, derived from bovine testes. It is a spreading or diffusing agent that temporarily increases tissue permeability by hydrolyzing hyaluronic acid, a polysaccharide found in the intercellular ground substance of connective tissue. This action facilitates the absorption and dispersion of other injected drugs, increases the rate of absorption of parenteral fluids given by hypodermoclysis, and aids in the resorption of excess fluids and blood in tissues. In the Indian context, it is a critical adjunct in various ophthalmic, dermatological, and emergency procedures.
| Onset | Duration | Bioavailability |
|---|---|---|
| Immediate upon injection. | 24 to 48 hours. | Not applicable (administered locally; systemic absorption is minimal and not therapeutically relevant). |
2. Mechanism of Action
Hyaluronidase is a hydrolytic enzyme that breaks down hyaluronic acid (HA) by cleaving the glucosaminidic bonds between C1 of the glucosamine moiety and C4 of glucuronic acid. HA is a key component of the extracellular matrix, providing viscosity and structural integrity. Its depolymerization reduces the viscosity of the interstitial barrier, decreasing tissue turgor and increasing permeability. This allows for enhanced diffusion of fluids, drugs, and contrast media through connective tissue.
3. Indications & Uses
- Adjuvant to increase the absorption and dispersion of other injected drugs (e.g., local anesthetics, antibiotics, corticosteroids).
- Hypodermoclysis (subcutaneous fluid administration) in pediatric and geriatric patients where IV access is difficult.
- As an adjunct in subcutaneous urography for improving resorption of radiopaque agents.
- Management of vitreous hemorrhage and to promote absorption of excess fluids/blood in tissues (e.g., periorbital hematoma).
4. Dosage & Administration
Adult Dosage: Highly variable based on indication. As an adjuvant: 15-150 IU (0.1-1 mL of 150 IU/mL solution) added to the injection solution or injected prior to the main drug. For hypodermoclysis: 150 IU added to 1 liter of clysis solution. For extravasation: 150-1500 IU injected subcutaneously in 5-6 sites around the extravasation area.
Administration: For injection: Reconstitute the lyophilized powder with sterile normal saline or the diluent provided to achieve a 1% (150 IU/mL) solution. Use immediately. Administer via subcutaneous, intradermal, or subconjunctival routes. DO NOT ADMINISTER INTRAVENOUSLY. For hypodermoclysis, infuse into the subcutaneous tissue of the thigh, abdomen, or lateral chest wall.
5. Side Effects
Common side effects may include:
- Local injection site reactions: erythema, itching, pain, swelling.
- Localized urticaria (hives).
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Local Anesthetics (Lidocaine, Bupivacaine) | Hyaluronidase increases the spread and absorption rate, potentially leading to faster onset but shorter duration of anesthesia. It may also increase systemic absorption and risk of toxicity. | Moderate |
| Salicylates (Aspirin), Cortisone, Estrogens, Antihistamines | These drugs may inhibit the spreading effect of hyaluronidase. | Moderate |
| Hyaluronic Acid Dermal Fillers (Restylane, Juvederm) | Hyaluronidase will rapidly degrade and dissolve hyaluronic acid fillers. This is a therapeutic interaction used for correction. | High |
7. Patient Counselling
- Do inform your doctor about any allergies, especially to beef or other enzymes.
- Do report any history of swelling, hives, or breathing difficulties after previous injections.
- Don't apply pressure or massage the injection site vigorously unless instructed.
- Do monitor the injection site for signs of increased redness, pain, or swelling.
8. Toxicology & Storage
Overdose: Overdose is unlikely due to local use. Theoretical effects include excessive tissue edema, increased systemic absorption of co-administered drugs leading to their toxicity, and severe allergic reactions.
Storage: Store the unopened vial at 2°C to 8°C (under refrigeration). Do not freeze. Protect from light. After reconstitution, the solution is stable for up to 24 hours if refrigerated at 2°C to 8°C, but it is recommended to use immediately for sterility. Discard any unused portion.