practice employs three preparations; (1) iodine tincture, (2) Lu-gol’s iodine and ( 3) povidone-iodine. The latter is the most useful
either for short-term first aid or long term surgeries (see Figure 3).
Over the years, tincture of iodine has prevented infections
in the hospital, home and battlefield. Despite decades of such
success, it has always possessed properties undesirable for practical application: unpleasant odor, staining and painfulness in
open wounds. The development of the iodophor carrier in the
late 1950-1960s, called“tamed iodine,” led to a distinct upgrade
in aseptic surgery, preparatory procedures and general first aid
treatment from inside the home to the hospital. The magic of the
iodophor discovery is in the presence of a “carrier” of the three
species to the wound site, not merely the absence of alcohol.
Among the 29 antiseptics cited in the September 2016 FR, the
iodophor alone supplied data indicating that the compound does
not convert an organism to drug resistance. 5
PVP-I has one of the widest ranges of kill/inactivation without resistance. This agent rapidly—seconds to minutes—works
against either the resident or transient flora of the skin including
Gram positive and negative bacteria, yeasts and molds including
conidial and hyphal forms and a broad range of enveloped and
naked viruses. In other words, molecular iodine, as for years in
the“tincture” captures the same breadth of activity when weakly
bonded inside of the PVP molecule as when dissolved in alcohol and infamously known as “Tincture of iodine.” The release
of iodine from the carrier provides two ionic and one molecular
(I2) form of the germicide. We note that only the latter molecular
form is biocidal.
Free molecular iodine released from the carrier penetrates the cell
walls of organisms and proceeds to oxidize sulfyhydryl groups.
Iodination of amino acids and lipids also contributes to the mi-crobiocidal activity of iodine. 6
The PVP carrier povidone (or polyvinylpyrolidone) is known to
SODIUM HYPOCHLORITE (NA+CLO-)
have been studied by German and American scientists in World
War II as a substitute for“blood plasma,” the liquid only part of
“whole blood.” Povidone-iodine (PVP-I) was discovered in 1955
by HA Shelanski, a toxicologist/microbiologist at the industrial
toxicology lab in Philadelphia while doing toxicity studies on
the PVP plasma substitute. He determined that when combined
with iodine it formed a stable molecule that was less irritating but
equally as active as the tincture. He named the new molecule“io-
dophor.” Human clinical trials eventually showed that the com-
pound was superior to other iodine formulations. 5
Commonly referred to as bleach, sodium hypochlorite is perhaps
the most well known consumer house-hold disinfectant and
bleaching agent. Similar to the other compounds reviewed in this
report, it appears on the WHO list of essential medicines under
the category of disinfectant. The usage of chlorine compounds
as bleaching agents and disinfectants date back to the late 17th
century. Although the usage of chlorine as a bleaching agent, wa-ter/pool treatment and a general purpose disinfectant are well
known, its historical use as an antiseptic is less known and will
be briefly reviewed here.
During World War I, an English chemist by the name of Henry
Dakin prepared a highly diluted sodium hypochlorite/boric acid
solution called Dakin’s solution in an attempt to treat battlefield
wounds. Prior to wound closure, Dakin’s solution was used for
wound disinfection and irrigation via administration through
perforated rubber tubing. The solution is credited to have helped
significantly reduce the rate of death and amputation during
Dakin’s solution (0.125-0.5%), manufactured by Century
Pharmaceuticals, is still used today as a broad-spectrum antimicrobial wound care solution
for acute and chronic wounds.
Although the antiseptic contains
the same active chemical used in
the disinfectant, certain dilutions
and treatments are performed
in order to reduce the inherent
skin irritation properties. Common household bleach sold at
“removed ~”1-8% sodium hypochlorite is effective against a wide
variety of aerobic and anaerobic
bacteria, yeast, molds and enveloped and non-enveloped viruses
(see Figure 4).
Dakin’s solution is a broad-spectrum antimicrobial cleanser effective against aerobic and anaerobic bacteria including common
resistant clinical strains, viruses, yeasts and molds. It is based on
the reactivity of the chlorine atom, which has proven useful from
the home to a terror site as either a disinfectant or antiseptic.
Sodium hypochlorite is a highly active oxidizing agent that targets
the sulfyhydryl groups of vital enzymes. The chlorine compound
quickly destroys phospholipids and restricts cellular metabolism.
In 2008, Winter et al. demonstrated that hypochlorous acid causes
the oxidative unfolding and aggregation of certain cellular proteins both in vitro and in vivo. 8 Despite extensive research, the
exact mechanism has yet to be fully elucidated. We point the
reader to the 5th edition of Block6 for a more in-depth analysis
FIGURE 4: Structural formula of
FIGURE 3: Structural formula of Povidone-iodine.