Phosphodiesterase V PDE

The drug sildenafil, sold imder the trade name Viagra, is a potent inhibitor of phosphodiesterase V (PDE V), an enzyme found in high levels in the corpus cavemosum of the penis. Inhibitors of this enzyme enhance vascular smooth muscle relaxation and are used for treatment of male impotence. Following is an outline for a s)mthesis of sUdenafil. 

FIGURE 14—5. The action of cGMP is terminated by the enzyme phosphodiesterase. In the penis, the type of phosphodiesterase is type V (PDE V). 

FIGURE 11.2 Interactions of vanadium with the hormone-sensitive G protein modulated cAMP producing signal transduction system. Bold lines with arrows leading away from V represent stimulation, blunt-ended lines represent inhibition. V shows where vanadium interactions have geen found. Pase phosphatase, PDE(IV) phosphodiesterase (IV), PEPCK phosphoenolpyrurate carboxykinase, PKA, protein kinse A inactive, PKAa PKA active. This figure was adapted from [13]. 

Phosphodiesterase Inhibitors — LM 209 (19) has been shown to be a noncompetitive inhibitor of lung phosphodiesterase (PDE) (2.5 x 10 4M) in contrast to theophylline, which is a competitive inhibitor. 19 is antihistaminic, orally effective and inhibits bronchospasm provoked by histamine, serotonin or citric acid. It is distinguished from other antihistamines by its lack of sedation and long duration of action. Absorption, distribution and elimination studies in rat and dog after i.v. or oral administration have been reported. ... 

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