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# Hyaluronic Acid ## Overview Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan found in various connective tissues. It acts as a lubricant and shock absorber. When used therapeutically, it is typically synthesized and administered as a viscoelastic solution. ## Primary Indications * **Intra-articular injection:** Osteoarthritis of the knee. * **Ophthalmic surgery:** Viscosurgical device for anterior chamber maintenance, corneal protection, and viscoelastic wound closure during cataract and other intraocular surgeries. * **Topical/Dermal:** Skin hydration, wound healing, and cosmetic applications (e.g., dermal fillers). *Note: These are often specific formulations and may not be universally classified as "drugs" in the same sense as injectables.* ## Adult Dosing * **Intra-articular (Knee Osteoarthritis):** * Dosing varies significantly by product. Common regimens include: * Single injection: 20 mg (2 mL) or 40 mg (2 mL). * Multiple injections: 20 mg (2 mL) administered once weekly for 3 consecutive weeks, or 5 consecutive weeks. * Refer to specific product labeling for exact dosage and administration schedule. Some protocols may suggest repeating treatment every 6 months. * **Ophthalmic Surgery:** * Used as needed during surgical procedures. Typical volumes administered range from 0.1 mL to 0.5 mL, depending on the surgical step and product viscosity. * Specific product guidelines must be followed. ## Pediatric Dosing Dosing for hyaluronic acid in pediatric patients is not established for most intra-articular or ophthalmic indications. Use is generally not recommended unless specifically indicated and under expert guidance. ## Dose Adjustments No dose adjustments are typically required for renal or hepatic impairment. Dosing is based on the specific formulation and indication. ## Contraindications * Known hypersensitivity to hyaluronic acid or any component of the formulation. * Active infection at or near the injection site. * Severe skin conditions at the injection site (for intra-articular). ## Adverse Effects * **Intra-articular:** Local pain, swelling, stiffness, transient joint effusion, arthralgia, bruising, itching, rash. Anaphylactic reactions are rare but possible. * **Ophthalmic:** Transient increase in intraocular pressure, post-operative inflammation, corneal edema, cystoid macular edema (rare). ## Key Drug Interactions * **Intra-articular:** Avoid concurrent intra-articular injection of corticosteroids, as this may increase the risk of infection or rapid joint degeneration (though some protocols explore sequential use). * **Ophthalmic:** Concurrent use with other ophthalmic medications should be evaluated carefully based on the specific surgical context. ## Monitoring * **Intra-articular:** Monitor for signs of local infection or allergic reaction. Assess pain and functional improvement. * **Ophthalmic:** Monitor intraocular pressure post-operatively. ## Clinical Pearls * Hyaluronic acid solutions vary in molecular weight and concentration, affecting their viscoelastic properties and clinical use. Always consult product-specific information. * For intra-articular use, proper aseptic technique is crucial to prevent infection. * Patient education regarding potential side effects and the expected onset of pain relief (which may be delayed) is important. *** *Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions. Dosing and recommendations may vary based on specific product formulations and local protocols.*