A few compounds of the 5(7)-alkylamino-6-nitroazolopyrimidine and 8-alkylazolo[5,1-b]purine series were selected based on the structural analysis of A1 adenosine receptor inhibitors and role of this biological target in the modulation of intraocular pressure which is an important factor in the pathogenesis of glaucoma. In this paper we synthesized six compounds of the 5(7)-alkylamino-6-nitroazolopyrimidine and 8-alkylazolo[5,1-b]purine series. It has been shown that these heterocycles possess low affinity towards A1 adenosine receptor in a model of adenosine-dependent changes in chronotropic effect in vitro on isolated atria of white mice. On the other hand, thiadiazolo[3,2-a]pyrimidines and triazolo[5,1-b]purine have shown hypotensive effect in vivo at rats: the leader compound (5-methyl-8-(hydroxyethyl)triazolo[5,1-b]purine) (0.2% solution) resulted in a 34% reduction in ophthalmotonus after 3 hours, while no undesirable resorptive effect was observed. In addition, heterocycles that affect IOP have been shown to exhibit 1–2 order less cytotoxicity than reference compound doxorubicin by MTT-test on the human HepG2 cell line.