Excretion of Mercury Following Administration of Mercurial Diuretics with and without Theophylline

Abstract

It has recently been shown that the addition of theophylline to the mercurial diuretics Mercurin and Salyrgan practically prevents their local toxic action 1 2 and promotes their absorption after intramuscular injection. 3 Although Mercupurin (Mercurin with theophylline) has been found to have a somewhat greater diuretic efficiency than Salyrgan, 4 5 6 7 it remains to be proven unequivocally, however, that theophylline exerts any influence after the drug has reached the circulation. It was therefore decided to study the excretion of mercury by laboratory animals after the administration of these diuretics with and without theophylline. It is fully realized that results thus obtained cannot necessarily be referred to man. Nevertheless, it was felt that information concerning the pharmacology of drugs of this type could more readily be obtained by using animals whose food, salt and water ingestion could be kept perfectly constant.

A total of 24 albino rabbits weighing between 2 and 3 kg were used in these experiments. All the animals had been raised on a diet of alfalfa hay and oats and had received a constant daily supply of water. On the day of the experiment each rabbit was tied to an animal board and 75 cc of water at body temperature administered by stomach tube. One hour later the animal was catheterized (French No. 10 catheter), the urine discarded and 0.10 cc of the drug to be studied was injected with a tuberculin syringe and 26 gauge needle either into the tibialis anterior muscle or one of the marginal veins of the ear. This was equivalent to 3.71 mg of mercury in the case of Salyrgan or Salyrgan with theophylline and 3.80 mg in the case of Mercurin or Mercupurin. The catheter was strapped in place with adhesive tape and all the urine excreted within the next 6 hours collected in 25 cc graduates. Since the rates of excretion vary considerably for the different drugs and methods of administration, it was necessary to space the collection of samples so that the time at which maximum excretion occurred could easily be determined.