Pentoxifylline (PTX) modulates immunologic activity by stimulating cytokine production. Pentoxifylline is a methylxanthine derivative that inhibits phosphodiesterase and affects blood rheology. It also inhibits platelet aggregation and improves blood flow by increasing erythrocyte and leukocyte flexibility.

Theobromine (3,7-Dimethylxanthine), a xanthine alkaloid, is used as a bronchodilator and as a vasodilator.

3-Methylxanthine, a xanthine derivative, is a cyclic guanosine monophosphate (GMP) inhibitor with an IC50 of 920 μM on guinea-pig isolated trachealis muscle. It inhibits xanthine crystallization and could protect patients with xanthinuria from developing renal xanthine calculi.