Congener drugs

Oil-soluble derivatives of testosterone itself predate those of its 19-nor congener these agents too are used to administer depot injections so as to provide in effect long-term blood levels of drug. Thus, acylation of testosterone with propionyl chloride in the presence of pyridine yields testosterone propionate (76a)acylation by means of decanoic anhydride yields testosterone decanoate (76b).Finally, reaction of 75 with 3-cyclopentylpropionyl chloride affords testosterone cypionate (76c)This last undergoes hydrolysis unusually slowly because of the presence of two substituents at the 5 position (see Newman s Rule of 6). ... 

The huge clinical success of drugs in this class has spawned an enormous list of congeners. Synthetic activity has, however, now slowed to the point that a separate chapter dealing with these heterocycles is no longer warranted. 

In the strict sense, opiates are drugs which are derived from opium and include the natural products morphine, codeine, thebaine and many semi-synthetic congeners derived from them. In the wider sense, opiates are morphine-like drugs with non-peptidic structures. The old term opiates is now more and more replaced by the term opioids which applies to any substance, whether endogenous or synthetic, pqrtidic or non-peptidic, that produces morphine-like effects through an action on opioid receptors. 

Medicinal chemists have a distinct advantage in pursuing mechanism-of-action studies because it is possible to synthesize a series of structurally related congeners and measure their biological activity. A correlation between activity and particular structural features not only helps to identify the pharmacophore, or active moiety imbedded within the molecule, but also may establish critical requirements or complementarity for the biological target or receptor for the particular drug class. 

PMEA and its congeners are more effective in vivo than could be predicted from their in vitro potency. While less potent as an antiretrovirus agent than AZT in vitro, PMEA proved clearly superior to AZT when the two drugs were compared for their effectiveness in vivo, in mice infected with murine Moloney sarcoma virus [51,52]. PMEA was also shown to be effective against various other retrovirus infections, including Friend leukemia virus (FLV), Rauscher leukemia virus (RLV), and LP-BM5 (murine AIDS) virus infection in mice, feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV) infection in cats, and SIV infection in macaque (rhesus) monkeys (for review, see Ref. 53). In the latter model [54], again PMEA proved far superior to AZT in suppressing several parameters of the disease. 

Campbell, M.A., S. Bandiera, L. Robertson, A. Parkinson, and S. Safe. 1983. Hepta-, hexa-, tetra- and dichloronaphthalene congeners as inducers of hepatic microsomal drug-metabolizing enzymes. Toxicology 26 193-205. 

Elucidation of the mechanism of action for virtually all biologically active substances has been a collaborative effort between scientists in a variety of disciplines. In the area of drug research, medicinal chemists have played important roles by providing series of homologs and congeners of prototype compounds. The development of potency series, where the in vivo action can be correlated with in vitro or biochemical effects, has often played a pivotal role in formulating hypotheses about mechanism of drug action at the molecular level. 

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