PVP-I

PVP-I in antiviral applications
PVP-I formulations are also known to have broad antiviral properties. These effects are mechanistically similar in principle to iodine's antibacterial activity. For example, the virucidal mechanisms of action of PVP-I have been determined to involve the inhibition of essential viral enzymes such as neuraminidase. The inactivation of this enzyme blocks viral release from the host cell, preventing further spread of the virus to uninfected cells. In addition, PVP-I also inhibits viral haemagglutinin, resulting in the blockade of attachment to host cell receptors. By simultaneously targeting both critical aspects of the viral machinery needed for replication, PVP-I reduces the likelihood of resistance emerging through sudden mutation.
Under such guidelines, PVP-I formulations have been shown to elicit viral inactivation of > 99.99% in test systems using a modified vaccinia virus. Virucidal efficacy has in some cases been determined to occur within 15 s of contact. Following a hand simulation study with the murine norovirus, it was found that hand washing with PVP-I was more effective than chlorhexidine and soft soap, a gold standard recommended by the WHO. PVP-I was also shown to be more virucidal against both enterovirus and coxsackievirus when compared to other disinfectants.

PVP-I for Hospital infection control
Hospital settings are particularly challenging for antisepsis, as antibiotic-resistant strains are a constant threat. PVP-I is widely used in surgical settings to prevent infection by ensuring preoperative decontamination. The aim of such decontamination is to reduce the risk of skin flora being introduced into sensitive areas once the skin barrier has been breached. Normal and innocuous bacterial flora that usually colonise healthy skin can become harmful in such settings, particularly for immuno-compromised individuals. A PVP-I surgical scrub with a detergent and foam booster is recommended for the most effective preoperative sterilisation.
Antisepsis agents were then used in a randomised approach and the number of test organisms released from the fingertips was calculated in terms of mean log10 reduction factor as per EN1499 guidelines. The direct comparison of PVP-I 7.5% and chlorhexidine 4% formulations showed a clear superiority of PVP-I against the murine norovirus, while both PVP-I and chlorhexidine were significantly better than soft soap against E. coli. Such experimental models could be helpful in broader assessments of antisepsis agents.

PVP-I for Hygienic interventions
It has long been known that hand washing, when performed properly, can significantly reduce the carriage and spread of pathogens. This has a direct effect on reducing patient morbidity and mortality from nosocomial infections. Hand washing is an important and established procedure for infection control with clinically-validated efficacy and a core component of protocols aimed at reducing infectious outbreaks. The skin can act as a reservoir for infectious agents, and the use of PVP-I for hand disinfection represents an alternative to alcohol-based hand rubs, with medicated soaps containing PVP-I now readily available. Such PVP-I soaps have shown equivalent or superior efficacy to alcohol-based hand sanitisers when tested against norovirus, a common cause of gastroenteritis. In contrast, chlorhexidine and triclosan-based hand washes, have been shown to be inferior against norovirus in practical application tests. Hand washing with PVP-I-based formulations have shown similar antimicrobial efficacy to an alcohol-based hand rub, with both being preferable to the use of soap and water alone.
PVP-I scrubs have better skin tolerance than soap formulations of chlorhexidine and quaternary ammonium compounds. Although there is an urgent need for well-designed studies directly comparing the clinical and economic profiles of antiseptics in such settings, PVP-I can be considered the antiseptic of choice for the management of superficial skin infections.

PVP-I Against antimicrobial-resistant bacterial strains
The PVP-I formulation containing up to 1% available iodine was able to kill all strains tested in under 5 min, with most cells being destroyed within 30 s. While dilute concentrations were noted to take in excess of 10 min to achieve an effect, even these iodine dilutions were successful in killing all strains upon prolonged exposure. In real-world scenarios, over-the-counter PVP-I formulations are accommodating of such prolonged exposure to healthy skin, with some commercial formulations known to be active for 12–14 h, compared to the 1–4 h of activity documented for chlorhexidine against fungi and endospores. Of particular note, clinical isolates of chlorhexidine-resistant Klebsiella pneumoniae that are also cross-resistant to colistin have recently been identified. While chlorhexidine is commonly used in disinfectants, these new findings suggest that exposure to chlorhexidine is associated with stable resistance to colistin, an antibiotic of last resort for multidrug-resistant infections.

Efficacy of PVP-I in comparison to other antiseptic agents
It has been more than 60 years since PVP-I was first marketed as an antibiotic/antiseptic agent. Since its introduction, various other agents including triclosan and carbapenem have been introduced, although it has been 30 years since a new class of antibiotic was last discovered.
According to recent reviews, there have been no confirmed reports of resistance to PVP-I to date. Numerous studies have shown that PVP-I has a broader antimicrobial spectrum than other available antiseptics including chloroxylenol, chlorhexidine, and quaternary ammonium compounds. Although alcohol-based antiseptics also have broad potency, unlike PVP-I formulations, they typically have no effect on fungal or bacterial spores. Interestingly, honey and maggots have been shown to have antibacterial properties when applied in therapeutic wound-treatment settings, although their potency in comparison to iodine against viruses and endospores remains to be determined.

PVP-I - Treatment of infection in burns
A 10% ointment of povidone-iodine(PVP-I)was developed after the active agent demonstrated a broad spectrum of antimicrobial attributes in liquid form. Although its active antimicrobial component is iodine, there has been no documentation associated with intact skin hypersensitivity or toxic effects. It has a broad spectrum of antibacterial and antifungal activities. Povidone-iodine(PVP-I) ointment can be employed effectively in both the closed and open techniques. Quantitative bacteriological assessments imply that iodine is most efficacious when it is administered every 6 hours. When it is used in this manner, it is effective in controlling and/or preventing bacterial colonization.
However, there are some adverse drug effects associated with the use of this topical antimicrobial at burn wound sites. The topical application of this agent is painful. Recent studies intimate that the iodine component of this topical agent may be absorbed more extensively in burn wound sites, resulting in iodine toxicity, renal failure, and acidosis. Concomitantly, povidone-iodine(PVP-I) has been shown to be cytotoxic to fibroblasts. However, it remains a highly effective disinfectant when used on intact skin.