[Blood level courses after i.v., i.m. and p.o. administration of theophylline ethylendiamine and pH-neutral solution of theophylline (author's transl)].

Serum theophylline concentration was measured in nine patients with chronic-obstructive lung disease following oral, i.m. and i.v. application. Two different preparations were tested: A pH-neutral solution of theophylline (Solosin) and theophylline-ethylenediamine. 208 mg of the pH-neutral solution of theophylline showed very similar serum concentrations as did 240 mg i.v. or p.o., but definitely higher than in the case of 360 mg i.m. theophylline ethylenediamine. After 10 min following the oral or the intramuscular application, serum concentrations were high enough for strong bronchodilating action. The oral dosages only reached the lower limit of optimal concentration for the best bronchodilation. There is a decrease of the blood concentrations by 50% after about 5 h. The bronchodilating effect subsided 2-4 h after i.v. injection.