Hyason (Hyaluronidase)

Hyason is employed in several clinical settings where increased tissue permeability is desired.

• As an adjunct to improve the dispersion of subcutaneously or intramuscularly injected drugs, such as local anesthetics or antibiotics.
• To facilitate retro‑bulbar anesthesia during ophthalmic surgeries by enhancing the spread of anesthetic agents.
• In the management of extravasation injuries, helping to disperse infiltrated fluids and reduce tissue damage.
• As a component of assisted reproductive techniques, for example to improve sperm motility during intrauterine insemination.
• To promote the absorption of subcutaneous fluid therapy in patients requiring rapid volume expansion.

• Hyaluronidase hydrolyzes the glycosidic bonds of hyaluronic acid, a major constituent of the extracellular matrix. By breaking down hyaluronic acid, the enzyme reduces viscosity of interstitial spaces and temporarily increases tissue permeability. This enzymatic action allows co‑administered substances to diffuse more readily through connective tissue, enhancing their distribution and absorption at the injection site. The effect is transient, typically lasting several minutes, after which normal extracellular matrix structure is restored.

Adverse reactions to Hyason are generally related to the enzymatic activity and the injection process.

Common

• Local pain, erythema, or swelling at the injection site.
• Transient bruising or mild hemorrhage.
• Temporary itching or tingling sensations in the treated area.
• Mild fever or chills within a few hours post‑injection.
• Transient headache not associated with other neurological signs.
• Temporary increase in local blood flow causing mild redness.

Serious

• Immediate hypersensitivity reactions, including urticaria or angio‑edema.
• Anaphylactic shock, characterized by respiratory distress, hypotension, or loss of consciousness.
• Severe systemic allergic response leading to cardiovascular collapse.
• Rare occurrence of localized tissue necrosis at the injection site.
• Severe systemic inflammatory response leading to multi‑organ dysfunction (extremely rare).

When prescribing or administering Hyason, several precautionary measures should be observed to minimize risk.

• Verify patient history for hypersensitivity to hyaluronidase or related enzymes before use.
• Avoid intravascular injection; ensure proper intramuscular or retro‑bulbar placement.
• Monitor patients closely for signs of allergic reaction during and after administration.
• Use with caution in patients with cardiovascular disease or uncontrolled asthma.
• Pregnancy and lactation status are not well established; consider risk‑benefit before use.
• Do not mix with other injectable solutions unless compatibility has been demonstrated.
• Store according to label instructions, protecting from light and extreme temperatures.

Hyason may interact with other agents that influence immune response or tissue permeability.

Avoid

• Concurrent use of other hyaluronidase preparations or high‑dose enzyme therapies.
• Simultaneous administration of agents known to cause severe allergic reactions (e.g., certain biologics) without appropriate monitoring.

Use with caution

• Co‑administration with vasodilators or antihistamines, which may modify hemodynamic responses.
• Use alongside anticoagulants, as increased tissue permeability could affect local bleeding risk.
• Combination with other ophthalmic anesthetics, requiring dose adjustments to avoid excessive spread.
• Administration with large volumes of subcutaneous fluids, monitoring for rapid systemic absorption.