Repository Injection of Penicillin in Water-in-Oil Emulsion. I. Effect on Gonorrhea. ∗

Abstract

There have been numerous efforts to improve the administration of penicillin by either prolonging its absorption 1 or delaying its excretion. 2 Most recently methods of administering penicillin by mouth have been reported. 3

This study was undertaken to determine if penicillin injected intramuscularly is more effective in a water-in-oil emulsion than in aqueous solution. It was hoped that the absorption of penicillin might be prolonged by incorporating it in a water-in-oil emulsion so that the number of injections and perhaps the amount of penicillin could be reduced. Patients with gonococcal infections were chosen for testing the method because clinical manifestations are usually clear-cut and cure can be established readily by bacteriological methods.

Water-in-oil emulsions were prepared by combining an aqueous solution of sodium penicillin with a lanolin-like substance† and peanut oil (other vegetable oils may be used). They contain microscopic droplets of aqueous solution of penicillin in a menstruum of oil and “Falba.”† (Fig. 1.) Such preparations can be made conveniently in a clinical laboratory as follows: One part of autoclaved and melted “Falba” is placed in a mortar and 1.3 parts of a penicillin solution are added to the “Falba” drop by drop while mixing with a pestle. Then 1.8 parts of autoclaved peanut oil are mixed slowly with the penicillin-“Falba” mixture. Solutions containing up to 200,000 units of sodium penicillin per ml can thus be incorporated; it has been found convenient, however, to use solutions containing 100,000 units per 1.4 ml of normal saline. A somewhat simpler procedure, particularly useful in preparing larger amounts of emulsion, is to mix the “Falba” with peanut oil and add the aqueous solution of penicillin slowly to the oil-Falba mixture while it is being agitated by an electric stirrer.

A single dose can be prepared without laboratory facilities in the following way: One and four-tenths ml of sterile 0.85% salt solution are drawn into a sterile syringe and ejected into a vial containing 100,000 Oxford units of dry penicillin.