Bibrocathol

Bibrocathol is a bismuth-containing substance which acts as antiseptic, adstringent and secretion inhibitng agent on mucous membranes and wounds. The mechanism of action is explained by its phenolic molecular structure consisting of tetrabromopyrocatechol and bismuth hydroxide that causes the precipitation of proteins and the shrinking of superficial layers of tissue. These activities result in the formation of a protective membrane against pathogenic invasion and non-specifically inhibit inflammation and secretion.

Bibrocathol is almost insoluble in water and therefore does not penetrate into aqueous humour of the eye. Therefore, its ophthalmologic use is limited to the topical treatment of chronic inflammation of the lid margin (Blepharitis chronica).

There is no remarkable systemic absorption after topical application.

Acute toxicity

The systemic administration of single intragastric bibrocathol doses vastly exceeding the therapeutic dose temporarily accelerated respiration and decreased activity of mice, but not in rats. No mortality was observed.

Subchronic toxicity

Multiple ophthalmologic bibrocathol doses up to 2-fold of the therapeutic dose in rats and up to 150-fold of the therapeutic dose in rabbits for 30 days did not result in appreciable adverse effects. The elevated levels of triglycerides or cholesterol determined in the blood of rabbits and rats, respectively, did not correlate with histological changes.

Genotoxicity and carcinogenicity

Bibrocathol did not show any genotoxic potential in bacteria and bone marrow cells of mice. Carcinogenicity studies were not performed.

Reproductive toxicity

In limited investigations of the reproductive toxicity in rats, ophthalmic administration of up to 2-fold of the therapeutic dose did not affect male and female fertility, embryogenesis or foetal and postnatal development.

Local tolerance in topical application

No ocular intolerabilities of bibrocathol were observed up to maximum dosages in repeated-dose toxicity studies in rats and rabbits. Single ophthalmic administration of up to 20% bibrocathol also did not induce hypersensitivities or effects on humoral, cell-mediated or non-specific immunity of guinea pigs and mice, respectively.