Preparation of 1-acyloxyethyl esters of 7-[2-(2-aminothiazol-4-yl)acetamido]-3-[[[1-(2-dimethylaminoe thy l)-1H-tetrazol-5-yl]thio]-methyl]ceph-3-em-4-carboxylic acid (cefotiam) and their oral absorption in mice

Prodrugs of butyric acid. Novel derivatives possessing increased aqueous solubility and potential for treating cancer and blood diseases

The synthesis and biological activities of acidic, basic and neutral types of butyric acid (BA) prodrugs possessing increased aqueous solubility are described. The compounds are butyroyloxyalkyl derivatives of carboxylic acids, which possess functionalities suitable for aqueous solubilization. The anticancer activity of the prodrugs in vitro was evaluated by examining their effect on the growth of human colon, breast and pancreatic carcinoma cell lines, and their solubility in aqueous media was determined. The most promising compounds, with respect to activity and solubility, were found to be the butyroyloxymethyl esters of glutaric 2a and nicotinic acids 4a and phosphoric acid as its diethyl ester 10a, which displayed IC(50) values of 100 microM or lower. These prodrugs are expected to release formaldehyde upon metabolic hydrolysis. The corresponding butyroyloxyethyl esters (2b, 4b and 10b) that release acetaldehyde upon metabolism were significantly less potent. A similar correlation was observed for growth inhibition of the human prostate carcinoma cell lines PC-3 and LnCap and for induction of differentiation and apoptosis in the human myeloid leukemia cell line HL-60. The higher biological activity of the formaldehyde-releasing prodrugs 2a and 10a was further confirmed when induction of hemoglobin (Hb) synthesis in the human erythroleukemic cell line K562 was measured. Moreover, a therapeutic index (IC(50)/ED(50)) of ca. 5 was observed. The acute i.p. toxicity LD(50) in mice for 2a, 2b, 10a and 10b was similar and in the range of 400-600 mg kg(-1). The results obtained support the potential use of the butyric acid prodrugs for the treatment of neoplastic diseases and beta-globin disorders.

Prodrugs of CL316243: a selective beta3-adrenergic receptor agonist for treating obesity and diabetes

CL316243 is a highly selective and potent beta3-adrenergic receptor agonist, and has been shown in rodent models to be an effective agent for treating obesity and Type II diabetes. To improve the oral absorption and pharmacokinetic profiles of CL316243, a number of prodrugs have been synthesized and evaluated. Several ester-type prodrugs show significant improvements in oral bioavailability in both rodent and primate models.

Discovery of the hemifumarate and (alpha-L-alanyloxy)methyl ether as prodrugs of an antirheumatic oxindole: prodrugs for the enolic OH group

Ether, ester, and carbonate derivatives of the antirheumatic oxindole 1 were prepared and screened as potential prodrugs of 1. This effort led to the discovery of the (alpha-L-alanyloxy)-methyl ether and hemifumarate derivatives of 1 which deliver the drug efficiently into the circulation of test animals, are stable in the solid state, and possess good stability in solution at low pH as required to ensure gastric stability. Success in achieving acceptable bioavailabilities of 1 across species (rats, dogs, and monkeys) followed the inclusion of ionizable functionality within the promoiety to compensate for masking the polar enolic OH group of the free drug. However, the introduction of ionizable functionality was often associated with decreased stability, as demonstrated by the hemisuccinate, hemiadipate, hemisuberate, and alpha-amino ester derivatives of 1 which could not be isolated. A clear exception was the hemifumarate derivative of 1 which was not only isolable but actually more stable at neutral pH than the nonionizable ester analogues. The solution and solid state stability of the hemifumarate, together with its activity as a prodrug of 1, suggests that hemifumarate be considered as an alternative to hemisuccinate as a prodrug derivative for alcohols, particularly in situations where solution state stability is an issue.

Glycolamide esters as biolabile prodrugs of carboxylic acid agents: synthesis, stability, bioconversion, and physicochemical properties

Benzoic acid esters of various substituted 2-hydroxyacetamides (glycolamides) were found to be hydrolyzed extremely rapidly in human plasma solutions, the half-lives of hydrolysis being less than 5 s in 50% plasma solutions for some N,N-disubstituted glycolamide esters. The rapid rate of hydrolysis could be largely attributed to cholinesterase (also called pseudocholinesterase) present in plasma. From a study of a variety of substituted glycolamide esters and structurally related esters, the most prominent structural requirement needed for a rapid rate of hydrolysis was found to be the glycolamide ester structure combined with the presence of two substituents on the amide nitrogen atom. A structural similarity of such esters with benzoylcholine, a good substrate for cholinesterase, was put forward. Esters of N,N-disubstituted glycolamides are suggested to be a useful biolabile prodrug type for several carboxylic acid agents. The esters combine a high susceptibility to undergo enzymatic hydrolysis in plasma with a high stability in aqueous solution. Furthermore, as demonstrated with the benzoic acid model esters, it is feasible to obtain ester derivatives with almost any desired water solubility or lipophilicity with retainment of marked lability to enzymatic hydrolysis.