Longer biological half-life

Artemisinin and its derivatives, artesunate and arthemether, kill both asexual and sexual blood stages (Fig. 2). However, artemisinins are quickly eliminated from the body, resulting in parasite recrudescence, and are therefore combined with schizontocides that have a longer biological half-life, such as amodiaquine,... 

The longer biological half-life appears to be due to low-body clearance value (1.26 0.08 ml/kg/min). The cumulative urinary excretion of parbendazole for 5 days was found to be very low (0.475 0.144%). Fecal excretion of the drug was slightly higher (4.20 0.71% of the total administered dose) and may be suggestive of biliary excretion [43]. 

It is, however, pertinent to state here that even though sulphanilamide has sufficient lipid solubility (10.5%) to cross the bacterial membrane, 99.7% of the total available molecules would usually remain in the molecular (inactive) state once inside. Based on the above statement of facts the existing difference in the lipoidal solubility between the two aforesaid drugs would certainly permit the scope of prediction that sulfadiazine should possess a distinct longer biological half-life. 

Longer biological half life with prolonged effective level... 

It is worth mentioning that the production of the 17-amino-17-demethoxy-geldanamycin, albeit in low yields, is remarkable. In fact, it has been shown recently that this derivative is the major active metabolite of 17-AAG, and is more potent than 17-AAG itself, and has a longer biological half-life in vivo. Thus, it seems worthwhile searching for the optimizated fermentation conditions to produce this promising derivative [190]. 

---