Microcyn Toxicology

The Microcyn formulation used in the toxicology studies is the same as that to be used in clinical studies on human subjects (Gutiérrez 2006). 

Since Microcyn is produced at only a single strength, the dose of Microcyn can only be varied by changes in the volume applied per unit of skin surface area.  The doses of Microcyn topically applied to intact skin in the toxicology studies ranged from 0.05 to 0.07 mL/cm2 in the acute dermal toxicity study to 8.0 mL/cm2 in the skin irritation study.   In full-thickness dermal wounds in rats Microcyn was applied at a dose of .09 mL/cm2.  Use of gauze squares “saturated” with Microcyn in the clinical studies on human subjects will result in an application rate of approximately 0.31 mL/cm2. 

The toxicology studies of Microcyn topically applied to intact skin were conducted using a single application with exposure for 4 to 24 hours.  Multiple applications of Microcyn, once or twice daily, over a period of 7 days were assessed in full-thickness dermal wounds in rats.  A one-minute single application topical use is anticipated for pre-operative skin preparation and will be used in clinical studies on human subjects. 

Two studies were conducted to assess the effect of Microcyn on intact skin; acute skin irritation in rabbits and acute dermal toxicity in rabbits.  No clinical signs, dermal irritation or abnormalities on gross necropsy were noted in any animals exposed to Microcyn on intact skin.

Characterization of local and systemic toxicities from topically applied Microcyn to a full-thickness dermal wounds was assessed in rats.   No abnormal clinical observations, significant differences in serum chemistry or hematology parameters, or abnormalities on gross necropsy, were noted in any of the animals.  Skin irritation scores and histopathology of the wounds and surrounding tissues did not reveal any differences between the Microcyn treated wounds and the saline control treated wounds.

Systemic toxicity of Microcyn was also assessed by intraperitoneal injection in mice.  No mortality or evidence of any systemic toxicity was observed in any of the animals receiving a single intraperitoneal dose of Microcyn.

Microcyn was administered by the oral route to rats to permit absorption and characterize any inherent toxicities of the product.  No mortality, clinical signs, or abnormalities on gross necropsy were noted in any animals exposed to Microcyn in a single oral dose.

The potential for ocular irritation from topically applied Microcyn was assessed in rabbits. No ocular irritation or other clinical signs were noted in any animals exposed to Microcyn via topical ocular administration.

Microcyn was administered by inhalation to rats to determine the acute inhalation toxicity potential.  All animals showed very slight or slight decreased activity and very slight piloerection after exposure but all were asymptomatic by the following day.  No mortality or abnormalities on gross necropsy were noted in any animals exposed to Microcyn by inhalation. 

The potential for skin sensitization from Microcyn was assessed in guinea pigs using a modified closed patch (Buehler) method.   No irritation was seen in the naive control animals after a single treatment challenge or in the test (induction treated) animals after the challenge treatment.  Therefore, Microcyn did not elicit a sensitizing reaction.

Genotoxicity, A major concern when using super-oxidized solutions is the potential induction of genotoxicity. In accordance, a micronucleus testing conducted as per ISO standards has shown that Microcyn is not genotoxic.