It appears from the investigations made to date that successful oral administration of penicillin may hinge on complete neutralization of the acidity of the stomach plus a relatively slow release of this drug from some chemical which adsorbs it readily. In 1929 one of us,1 following the studies of Gross,2 utilized magnesium hydroxide in the purification of diphtheria toxin. It was noted at that time that this metallic hydroxide selectively adsorbed diphtheria toxin quite firmly in the presence of proteins. After adsorption vigorous treatment was required for the release of the exotoxin from the magnesium. Other metallic hydroxides acted similarly but appeared to be less effective in their binding power. However, in all cases selective adsorption occurred rapidly, resulting in a relatively pure diphtheria toxin.
On the basis that possibly penicillin, a biologic excretory product of a mold, might behave similarly, several manufacturers' products were treated with aluminum
WELCH H, PRICE CW, CHANDLER VL. PROLONGED BLOOD CONCENTRATIONS AFTER ORAL ADMINISTRATION OF MODIFIED PENICILLIN. JAMA. 1945;128(12):845-847. doi:10.1001/jama.1945.02860290007002