Povidone-Iodine (PVP-I) CAS No. 25655-41-8

Surgical and Procedural Antisepsis: Widely used for skin preparation before surgery (e.g., neurosurgery, craniotomy, fascia lata graft harvesting) to reduce infection risk. Applied as a 10% solution; effective in preventing surgical site infections but requires careful application to avoid pooling.

Treatment of Ocular Infections: Effective in managing infectious keratitis (corneal ulcers) and endophthalmitis (e.g., fungal cases like Arthrographis kalrae). Used topically (e.g., 5% solution) or infused during pars plana vitrectomy (dilute 0.05% in balanced salt solution) to eradicate fungi while awaiting culture results. Reduces infiltrate/ulcer size and colony-forming units (CFUs); alternative in resource-limited settings where fortified antibiotics are unavailable.

Pleurodesis and Respiratory Management: Chemical pleurodesis for congenital chylothorax in infants; e.g., 2 mL of PVI mixed with lidocaine and saline, instilled via chest tube, repeated every other day. Reduces pleural effusion output rapidly, leading to resolution without recurrence.

Graft and Tissue Preparation: Soaking tendon grafts (e.g., porcine flexor tendons) in a 0.35% solution for 3-30 minutes to prevent intraoperative contamination during reconstructions (e.g., ACL surgery). Eliminates bacteria without significantly harming biomechanical properties.

Catheter-Related Infection Prevention: Skin disinfection for vascular access devices (e.g., central venous catheters) to prevent catheter-related bloodstream infections (CRBSIs). Recommended as a 10% aqueous or alcohol-based solution; alternative to CHG in cases of intolerance. Reduces microbial colonization at insertion sites.

Wound Care and Burn Management: Topical application for wound cleaning and preventing secondary infections; e.g., in chemical burns or postoperative care. Used with silver sulfadiazine for healing.

Other Applications: Adjunct in global eye care for antibiotic-resistant infections; potential low-cost alternative in rural/underprivileged settings. Not superior to antibiotics alone in some studies but beneficial when added to standard care.

Chemical Composition and Structure: Povidone-Iodine (PVP-I) is an iodophore, a complex of elemental iodine with povidone (polyvinylpyrrolidone or PVP). PVP acts as a carrier to solubilize and stabilize iodine, reducing its irritant and corrosive properties while retaining antiseptic efficacy. The complex releases free iodine gradually upon application.

Physical Properties: Available as a solution (e.g., 10% w/v for skin prep, or diluted to 0.35% or lower for specific uses). It has a brownish color and is water-soluble. In dilute forms, it can be infused or soaked without immediate precipitation.

Antimicrobial Spectrum and Mechanism: Broad-spectrum antiseptic effective against bacteria (including MRSA and multidrug-resistant organisms), fungi (e.g., Fusarium, Aspergillus, Arthrographis kalrae), viruses, and protozoa. It works by releasing free iodine, which penetrates microbial cell walls, oxidizes proteins, enzymes, and nucleic acids, leading to cell death. It has residual activity (persists on skin for hours) and is enhanced by alcohol (e.g., isopropyl alcohol) in formulations, which aids in rapid drying and additional antimicrobial action.

Biomechanical and Tissue Effects: Can alter tissue size and properties; e.g., soaking porcine flexor tendons in 0.35% PVI increases cross-sectional area (CSA) by ~6-12% (similar to saline), potentially due to swelling from osmotic effects. No significant impact on tendon stiffness, load at failure, modulus, or stress at failure in most cases, but may reduce collagen and glycosaminoglycan (GAG) distribution subtly on histology.

Pharmacological Variations: Efficacy varies by concentration (e.g., 10% for skin prep, 0.35% for tendon soaking, dilute 0.05% for intraocular use). Alcohol-based formulations (e.g., PVI-IPA) improve efficacy but may increase irritation. It has low systemic absorption but can affect thyroid function with prolonged use.

Environmental Persistence: Higher persistence and potential ecological risk compared to chlorhexidine (CHG), as it may bioaccumulate or affect aquatic life.

Adverse Effects and Toxicity: Can cause chemical burns (deep partial-thickness) with prolonged skin exposure or pooling (e.g., during surgery), leading to erythematous lesions, blistering, pain, and scarring. Reduces tenocyte viability in tendons (e.g., 14.4% viability after 0.35% exposure vs. 35.4% in controls), with tendinous portions more susceptible than entheses. In eyes, dilute forms are nontoxic, but higher concentrations may cause irritation. Potential for thyroid disruption (e.g., elevated TSH) with systemic absorption. Allergic reactions (e.g., contact dermatitis) possible, though less common than with elemental iodine.

Handling Precautions: Apply with proper technique (e.g., avoid pooling under drapes or prolonged contact). Rinse after use if needed. For intraocular use, dilute to 0.05% to minimize toxicity. Monitor for signs of irritation in sensitive areas (e.g., thighs, eyes). In pleurodesis, clamp tubes post-instillation and rotate patient to distribute evenly. No safety concerns reported in dilute topical/ocular use for keratitis.

Contraindications and Risks: Avoid in patients with iodine allergy or thyroid disorders. Less effective than 2% CHG-IPA in some comparisons for infection prevention. Environmental risks include higher persistence than CHG, potentially harming ecosystems. In resource-limited settings, balance benefits with availability.

Management of Adverse Events: For burns, use wound care with silver sulfadiazine, NSAIDs for pain; heals in 2-3 weeks with possible depigmented scars. No long-term toxicity in dilute intraocular use.