Summary
In 1915 four Edinburgh pathologists reported that free hypochlorous acid, made from bleaching powder and boric acid, killed bacteria and anthrax spores in the lab and cleaned septic wounds faster than boric acid soaks in their first clinical use. The clinical observations were uncontrolled, and the authors called them an early stage.
Key points
- Aim: an antiseptic for the first dressing in the field that destroys spores. They found hypochlorous acid more potent than its salts (hypochlorites) and made it from equal parts bleaching powder and boric acid: a powder ("Eupad") and a solution ("Eusol").
- Eusol recipe: 25 g of the powder per liter of water, or 12.5 g of each ingredient in a liter, filtered after standing. It held about 0.54% hypochlorous acid, and 0.5% stayed effective for three weeks to a month.
- Lab: 0.5% killed E. coli, Staphylococcus and anthrax spores in 2 minutes, where 1 in 20 phenol did not kill the anthrax. At 0.25%, only 1 of 8 anthrax tests was sterile.
- Rabbit injections: 0.37% was tolerated by every route. 1.7% was fatal intravenously and intraperitoneally, and caused muscle damage along the track when injected into muscle.
- Clinical: over 100 cases. In more than 50 outpatient cases, most septic wounds were clean in 1 to 3 days and healed in 7 to 14 days, against 4 to 6 days to clean with boric soaks. The powder caused pain or slight blistering in some cases.
- Their conclusion: it is "the most powerful antiseptic known", toxic effects are purely local, and a gallon of solution cost about a penny. They advise stopping once sepsis is gone, and note it tarnishes metals.
- Limits: the paper describes no randomization, and the clinical comparisons with boric acid and iodine are reported for groups of cases. The authors say this part of the work is at an early stage.