Hypoxanthine is a naturally occurring purine derivative and a reaction intermediate in the metabolism of adenosine and in the formation of nucleic acids by the salvage pathway. Hypoxanthine is a necessary additive in the certain cell, bacteria, and parasite cultures as a substrate and nitrogen source. For example, it is commonly a required reagent in malaria parasite cultures, since Plasmodium falciparum requires a source of hypoxanthine for nucleic acid synthesis and energy metabolism.

Didanosine was developed by Bristol-Myers Squibb in collaboration with the NIH for the treatment of HIV-1 infections. Upon administration the drug is metabolized to the active metabolite which inhibits HIV-1 reverse transcriptase both by competing with deoxyadenosine 5'-triphosphate and by its incorporation into viral DNA. Didanosine was approved by FDA under the name Videx (among the other names).

Inosine is a naturally occurring nucleoside which serves as an intermediate in purine metabolism. The metabolism of purines in humans generates a potent antioxidant compound, uric acid, which is known to be a natural scavenger of both oxygen and nitrogen reactive species as well as having chelator properties. Inosine, as a precursor of uric acid, was shown to have neuroprotective effect in vitro and is being tested in phase III of clinical trials for the treatment of Parkinson disease. The treatment with inosine is belived to prevent or slow the disease.