1. Clinical Overview
Hyaluronidase is a hydrolytic enzyme that depolymerizes hyaluronic acid, a major component of the extracellular matrix. It acts as a 'spreading factor' by temporarily decreasing the viscosity of the interstitial barrier, facilitating the diffusion and absorption of other injected fluids, drugs, and contrast media. The 1500IU strength is a common injectable preparation used for subcutaneous fluid administration (hypodermoclysis), enhancing local anesthesia, and improving the dispersion of other injectable drugs.
| Onset | Duration | Bioavailability |
|---|---|---|
| Immediate upon injection. | 24 to 48 hours. The effect is temporary as the body regenerates hyaluronic acid. | 100% when administered via subcutaneous or intradermal routes, as it acts locally. |
2. Mechanism of Action
Hyaluronidase hydrolyzes hyaluronic acid, a glycosaminoglycan polymer found in the interstitial spaces of connective tissue. By breaking the glucosaminidic bonds between C1 of the glucosamine moiety and C4 of glucuronic acid, it reduces the viscosity of the ground substance. This decreases tissue barrier resistance and increases tissue permeability, allowing for enhanced diffusion and absorption of co-administered fluids and drugs.
3. Indications & Uses
- Adjuvant to increase the absorption and dispersion of other injected drugs
- Adjuvant in subcutaneous fluid administration (hypodermoclysis) for rehydration
- Enhancement of the efficacy of local anesthetics in infiltration anesthesia
- Management of extravasation of contrast media or certain drugs (e.g., vinca alkaloids, aminophylline)
4. Dosage & Administration
Adult Dosage: Highly variable based on indication. Common: 1500 IU added to 1 liter of fluid for hypodermoclysis. For local anesthesia enhancement: 150 IU added to the local anesthetic solution. For extravasation: 1500 IU in 1-2 mL saline injected subcutaneously into the affected area.
Administration: For reconstitution: Use only supplied diluent or sterile normal saline. Do not shake vigorously. Administer via subcutaneous injection, intradermal wheal, or as an additive to other solutions for SC infusion. NEVER administer intravenously for local indications. For extravasation, multiple small injections around the infiltration site are recommended.
5. Side Effects
Common side effects may include:
- Local injection site reactions: erythema, pain, swelling, itching
- Localized urticaria (hives)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Local Anesthetics (Lidocaine, Bupivacaine) | Hyaluronidase increases the spread and absorption of local anesthetics, potentially increasing their systemic absorption and risk of toxicity. It also shortens their duration of action. | Moderate |
| Salicylates (Aspirin), Corticosteroids (Hydrocortisone) | These drugs may inhibit the effect of hyaluronidase. | Moderate |
| Adrenaline (Epinephrine) | Adrenaline may delay the absorption of substances dispersed by hyaluronidase. Often co-administered to prolong local effect. | Moderate |
| Antihistamines (Diphenhydramine) | May interfere with the enzymatic activity of hyaluronidase. | Mild |
| Hyaluronic Acid Fillers (Dermal Fillers) | Hyaluronidase will rapidly degrade hyaluronic acid-based dermal fillers. This is a therapeutic use for complication management. | Major (Intentional Interaction) |
7. Patient Counselling
- Do inform your doctor about any allergies, especially to bee stings, bovine proteins, or previous enzyme injections.
- Do report any signs of infection at the injection site (increased redness, pain, pus, fever).
- Don't rub or massage the injection site vigorously unless instructed.
- Don't apply extreme heat or cold to the injection area immediately after the procedure.
8. Toxicology & Storage
Overdose: Overdose is unlikely due to local administration and rapid inactivation. Theoretical overdose could lead to excessive tissue permeability, widespread edema, and potential for increased systemic absorption of co-administered drugs, leading to their toxicity.
Storage: Store unopened vials at 2°C to 8°C (in a refrigerator). Do not freeze. Protect from light. After reconstitution, use immediately. Discard any unused portion. Do not use if the solution is cloudy or contains particulate matter.