Abstract: Classification algorithms are proposed based on information entropy and applied to 13 human immunodeficiency virus type 1 inhibitors. A number of results are compatible with the data suffering combinatorial explosion. After the equipartition conjecture, entropy production is most uniformly distributed. In ddI the formula is N₄O₃S₀P₀ , X = F, Cl; it is selected as a reference . In most cases (ddI, ddC, d4T, novel proposed ligand) the formula is N_3–4O₃S₀P₀X₀ , while in 3TC the formula is N₃O₃S₁P₀X₀. The analysis compares well with other classification taken as good.