ABSTRACT
The vast majority of chemical compounds used as drugs are small molecules of molecular weight 200 to 300 Da. Few drugs are administered as conjugates, but many drugs form conjugates in vivo. It was originally thought that formation of conjugates was a final step in making xenobiotics water soluble for elimination in the urine and thus little attention was given to the analysis of the conjugates. The process development chemist in the pharmaceutical industry is responsible for creating an efficient and economic method of preparing commercially useful amounts of new drugs. Prodrugs are chemical structures which are not pharmacologically active, but in the body are converted to an active molecule. In general, the prodrug has chemical characteristics, such as stability, lipophilicity, state of ionisation, that increase its chances of reaching its site of action, or which protect intervening biological structures from the effect of the active drug.
