Percutaneous Absorption of Boric Acid from Boron‐Containing Preparations in Rats

Abstract

An aqueous jelly and two oleaginous ointments containing less than 3% boric acid w/v, were applied on the skin of anaesthetized rats. When application was made on the intact skin of the dorsal surface (about 28 cm 2 ) determination of boric acid concentrations in the urine 8 hours later showed no or slight increases above the normal level. When the skin was damaged the ointments caused increased excretion up to 4–8 times that of the excretion found in control animals, while the jelly caused a 34 times increase. When an enclosed skin area of 4.3 cm 2 was damaged and treated, and simultaneous recording of boric acid recovery in both the urine and applied preparations (jelly and one ointment) was made 5 hours later, about 98 % boric acid still remained in the ointment, but only 25% in the jelly. The recoveries in the urine were 1% and 25% respectively, indicating slight absorption and rapid excretion in the case of the oleaginous ointment, and high absorption with inadequate excretion when the aqueous jelly was applied.