Drug administration prodrugs,

Of interest here is that certain drugs and prodrugs that contain an isoxazole ring are metabolized to a cyano enol, e.g., leflunomide (11.122, R = CF3, R = H), a prodrug of the potential anti-arthritic agent 2-cyano-3-hydroxy-A-[4-(trifluoromethyl)phenyl]but-2-enamide (11.123). After oral administration of 50 mg/kg of 11.122 to rats, the plasma concentration of the prodrug peaked at 1 pg/ml and dropped rapidly, whereas the concentration of the active metabolite 11.123 was maintained at ca. 100 pg/ml for 24 h [147]. This... 

Mycophenolic acid (MPA) was isolated from cultures of Penicillium spp. in 1896 and was purified in 1913. Initially the compound was studied for its antifungal and antibacterial effects and later for its antitumor effects. Many years later, its immunosuppressive activities were recognized and after further developmental work, an ester prodrug mycophenolate mofetil was developed, which was approved by the United States Food and Drug Administration for the prevention of acute renal allograft rejection in 1995 and for heart transplant recipients in 1998. Mycophenolate mofetil is a cytotoxic agent now used for immunosuppressive therapy and is the mofetil ester of MPA, which is the active immunosuppressive agent. 

Odour and taste are important aspects of drug administration. A drug with a poor odour or too bitter a taste will be rejected by patients, especially children. Furthermore, a drug that causes pain when administered by injection can have a detrimental effect on a patient. The formation of a carrier prodrug can sometimes alleviate some of these problems. For example, palmitic acid and other long chain fatty acids are often used as carriers, since they usually form prodrugs with a bland taste. 

The present review deals essentially with enhancement of gastrointestinal availability cf drugs through prodrug administration, but some other aspects of the prodrug concept are also discussed briefly. 

Prodrug. A precursor that, after administration and subsequent transformation in the body, forms the active drug. 

Another method of delivery of drug to the anterior segment of the eye that has proved successful is prodrug administration [144]. Since the corneal surface presents an effective lipoidal barrier, especially to hydrophilic compounds, it seems reasonable that a prodrug that is more lipophilic than the parent drug will be more successful in penetrating this barrier. 

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