Antiviral agents valacyclovir

Some drugs with low intrinsic permeability achieve acceptable oral bioavailability because they are substrates for uptake transporters, which normally function in nutrient uptake. The most prominent example is the peptide transporter, PepTl, which is active toward peptidomimetic antibiotics such as cephalexin, the antiviral agent valacyclovir [24] and other drugs. PepTl is natively expressed in Caco-2 cells, and adenovirus transduction has been used to increase PepTl expression levels [25]. However, the expression of PepTl was not polarized in this system and this expressed system appears to be of limited value as an improved screening model. PepTl has also been expressed in Chinese hamster ovary cells and a variety of other mammalian systems [26, 27]. 

Detailed pharmacology of acyclovir, valacyclovir, penciclovir and famciclovir is discussed in detail in chapter Chemotherapeutic agents- Antiviral agents. ... 

The use of trimethoprim-sulfamethoxazole in cancer patients at risk for P. jiwveci pneumonia has reduced the incidence of this protozoal infection substantially. Antiviral prophylaxis with acyclovir or newer agents (valacyclovir and famciclovir) is employed in most centers to reduce the risk of HSV reactivation in patients with acute leukemia undergoing intensive chemotherapy. Varicella vaccine provides good protection (90%) in leukemic children and also may be useful in seronegative adults, although the vaccine has been less well studied in this population. 

U87 Valaciclovir ValACV Valacyclovir. Antiviral agent. Prodrug of acyclovir. Glaxo Wellcome Inc. 

Figure 9.15 An example of the use of a prodrug to improve carrier-mediated transport. Valacyclovir, an L-valine ester prodrug, is transported across intestinal epithelial cell membranes by the HPTl and PEPTl transporters, and is then enzymatically hydrolyzed to the antiviral agent acyclovir before being converted to the true active component, acyclovir triphosphate, in cells.

Any prior history of viral infections, such as chronic or recurrent herpes simplex, active dermatoses of the atopic, seborrheic or eczematous types, and medications such as topical or oral retinoids, must be reviewed. Those patients with a history of recurrent herpes infection should be treated prophylactically with oral antiviral agents, preferably Valtrex (valacyclovir), on the morning of the peel and continued for a routine course of therapy. If the patient presents on the morning of the peel with active herpetic infection in the areas to be treated, it is best to postpone the peel until complete resolution has occurred. 

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