Povidone: Action as Excipient and Carrier
Povidone, chemically polyvinylpyrrolidone (PVP), is a synthetic polymer used in pharmacy and medicine in two important functions. As an excipient in tablets, eye drops, suspensions and ointments, povidone provides consistency, film formation and stability. As a complexed active ingredient in the form of povidone iodine (PVP iodine, brand names Betaisodona, Braunol, Polyiodine), it is one of the most important antiseptics in ambulatory and inpatient wound care.
In tear replacement with povidone, patients benefit from the film-forming property, which creates prolonged protection of the eye surface. In eye drops such as Lac Ophtal or Vidisept, povidone is a central component. As an antiseptic, povidone iodine combines the disinfecting effect of iodine with gentler application via the polymer complex. Compared to classical iodine solution, tolerance is significantly better.
Mechanism of Action
Povidone (PVP) is a water-soluble polymer with high viscosity in solution. It forms stable films on mucous membranes and skin surface, binds water and creates a protective layer. In the tear film, it prolongs the residence time of aqueous components and stabilizes the lipid layer. The effect is physical, the polymer has no pharmacological activity in the classical sense.
With povidone iodine, iodine is chemically bound to the polymer. The iodine is slowly and controlledly released once the solution comes into contact with mucous membrane or wound tissue. The released iodine acts microbicidally through oxidation of bacterial proteins, enzymes and cell membranes against bacteria (including MRSA), fungi, viruses (including HIV and SARS coronaviruses), mycobacteria, spores and protozoa. This very broad spectrum of action makes povidone iodine one of the most important antiseptics.
Systemic resorption is low. In deeper wounds or with large-scale application, iodine can be resorbed and influence thyroid parameters, especially in at-risk patients. Pure povidone without iodine component is not resorbed and is pharmacokinetically unremarkable.
Areas of Use
- Tear replacement and dry eye, eye drops with povidone for stabilization of the tear film
- Wound antisepsis with povidone iodine for acute and chronic wounds, burns, surgical fields
- Preoperative skin disinfection, especially on sensitive skin areas
- Mucosal antisepsis for mouth and throat rinses, vaginal antisepsis, perioperative antisepsis
- Galenic application in tablets, suspensions, eye drops, transdermal patches as excipient
- Diabetic foot syndrome and chronic wounds in specific wound care concepts
- Mouth and throat antisepsis for aphthae, gingivitis, postoperatively
Povidone and povidone iodine are not intended for systemic application. In case of iodine hypersensitivity, thyroid autonomy, lithium therapy, pregnancy (especially in the second and third trimester) and in infants, povidone iodine should be used restrictively.
Dosage and Administration
Eye drops with povidone: one drop in the lower conjunctival sac three to four times daily, more or less frequently depending on severity of symptoms. An additional application before bedtime is often recommended.
Povidone iodine solution 7.5 or 10 percent: apply directly to the wound or skin, allow to work briefly, rinse with physiological saline if necessary. For intact skin, a contact time of approximately 30 seconds is sufficient.
Povidone iodine ointment 10 percent: apply thinly to the wound, use dressing if necessary. Daily wound inspection for chronic wounds.
Mouth and throat rinses with povidone iodine: move 10 ml undiluted or diluted in the mouth, approximately 30 seconds, then spit out. Do not swallow.
Vaginal application: rinse solution according to manufacturer, or vaginal suppositories, individual treatment duration.
Renal insufficiency and hepatic insufficiency: povidone without iodine is not resorbed and unproblematic. With povidone iodine, caution in deep wounds with iodine resorption.
Side Effects
Frequent (eye drops): temporary blurred vision, burning, tearing.
Frequent (povidone iodine): skin irritation, pruritus, local burning sensation, temporary skin discoloration.
Occasional: contact allergy to iodine, allergic contact dermatitis, mucosal irritation with prolonged application.
Rare: systemic iodine resorption with impairment of thyroid function (hyperthyroidism, hypothyroidism), with large wound areas or burns with extensive application.
In infants: increased risk of iodine resorption with impairment of thyroid function. In newborns, restrictive application.
With thyroid autonomy: risk of iodine-induced hyperthyroidism. With autonomous adenomas and latent hyperthyroidism, povidone iodine is not first choice.
Interactions
- Mercury-containing dressings or antiseptics: formation of caustic compounds, avoid combination.
- Hydrogen peroxide: mutual inactivation, therefore do not use simultaneously.
- Other antiseptics (octenidine, chlorhexidine): rarely combined in practice because a single antiseptic solution is usually sufficient.
- Iodine-containing contrast agents and systemic iodine therapy: additional iodine burden possible, caution with thyroid autonomy.
- Lithium: combined effect on thyroid, caution.
- Phytotherapeutic wound treatments with honey or herbal tinctures: mutual effects should be considered.
Special Notes
Pregnancy: povidone without iodine is safe. Povidone iodine should not be used on large areas, especially in the second and third trimester, because iodine crosses the placental barrier and can cause thyroid disorder in the fetus. Brief, small applications are usually acceptable. Breastfeeding: iodine passes into breast milk, with large-scale application caution and consultation with pediatrics recommended.
Infants and newborns: application only briefly and on small areas, ideally with alternative antiseptics without iodine, such as octenidine.
Thyroid disorders: with autonomous adenoma, latent hyperthyroidism or planned radioiodine therapy, povidone iodine is not recommended because relevant iodine resorption may affect diagnosis and therapy.
Before operations: povidone iodine is one of the established preoperative skin antiseptics. For iodine allergy, alternatives such as chlorhexidine or octenidine are available.
Wound care: povidone iodine is suitable for acute wounds and burns. For chronic wounds, the evidence regarding promotion or inhibition of wound healing is mixed; individual wound care concepts and phase-appropriate therapy are more appropriate than routine continuous application.
Driving ability: temporary blurred vision with eye application, otherwise usually not impaired.
You might also be interested in
- Carbomer, another polymer in eye drops
- Dexpanthenol, skin regenerating care
- Chlorhexidine, alternative antiseptic for iodine intolerance
- Sodium perchlorate, for iodine-induced hyperthyroidism
- Cromoglycic acid, another active ingredient in eye drops
Frequently Asked Questions
How does povidone differ from povidone iodine?
Povidone (PVP) is a pure polymer without iodine, used in eye drops and galenic preparations. Povidone iodine (PVP iodine) is povidone with chemically bound iodine and acts as an antiseptic through slow iodine release. Both have different areas of use and safety profiles.
Does povidone iodine help with every wound?
It is a proven antiseptic for acute wounds, burns and surgical fields. For chronic wounds, the evidence is mixed, some studies describe delayed granulation. Modern wound care selects the antiseptic phase-appropriately and avoids routine continuous application.
Why does povidone iodine discolor the skin?
Iodine has an intense brownish-red color. It is harmless and can be washed off with water and soap. The discoloration is even diagnostically helpful because it makes the distribution of the antiseptic visible.
When should I not use povidone iodine?
With known iodine allergy, thyroid autonomy, latent or manifest hyperthyroidism, before radioiodine therapy, in newborns and with large-scale application in late pregnancy. In these cases, alternative antiseptics such as chlorhexidine or octenidine are more suitable.
Sources
- Gelbe Liste, Povidone Iodine Active Ingredient Profile
- BfArM, Federal Institute for Drugs and Medical Devices
- AWMF, Guidelines for Wound Care and Antisepsis
- German Ophthalmological Society
Legal Notices and Disclaimer
The information provided on this page is for general information purposes only and does not constitute medical advice, diagnosis or treatment recommendation. It does not replace the advice of an approved physician or pharmacist. For deep, infected or chronic wounds, medical consultation is necessary. All information is based on expert information and recognized scientific sources published at the time of creation; the currently valid expert information from the manufacturer is always authoritative. Sanoliste assumes no liability for completeness, timeliness or accuracy of the information presented. In a medical emergency, call emergency number 112.