Vidarabine

The D arabinose analog of adenosine is an anitiviral agent (vidarabine) used to treat con junctivitis and shingles Wnte a structural formula for this compound... 

ANTTBIOTTCS - BETA-LACTAMS - BETA-LACTAMASE INHIBITORS] (Vol 3) 2pDeoxycoformycin (co-vidarabine, pentostatin) [53910-25-1]... 

Antiviral Agents. Although a number of antibiotics have been shown to have some sort of antiviral activity, only vidarabine [5536-17-4] (adenine arabinoside) is used clinically against viral infections at this time. As the need for new antiviral agents (qv) increases and new screening procedures are developed, one would expect the discovery of other new effective antiviral antibiotics that could be used safely in human therapy. 

Purine Nucleoside Derivatives. A number of purine nucleoside analogues are also found to be active against several DNA vimses (Fig. 3). The clinically active antiviral drug ara-A (9-P-D-arabinofuranosyladenine [5536-17-4] vidarabine, 23) is active against a number of DNA vimses in vivo and also inhibits certain RNA tumor vimses which repHcate through a DNA intermediate (43). Ara-A, was first synthesized in 1960 (44) and later... 

CI3OP 10025-87-3) see Cyclophosphamide Estramustine phosphate Etopophos Ifosfamide Miltefosine Torasemide Vidarabine... 

Feedback interference/lactose, sugar alcohols, H2 antagonists, carbamazepine, vidarabine, isradipine, dopaminergics, finasteride Feedback interference (proestrogens, finasteride, methoxychlor, cadmium) Feedback interference (proestrogens, dopamine agonists)... 

Vidarabine inhibits vitally induced DNA polymerase more strongly than it does the endogenous enzyme. Its use is now limited to topical treatment of severe herpes simplex infection. Before the introduction of the better tolerated acyclovir, vidarabine played a major part in the treatment of herpes simplex encephalitis. 

Currently, amantadine, vidarabine, trifluridine, idoxuridine, sciclovir, ribavirin, and zidovudine are used as antiviral drugs. An analysis of the mechanisms of action of existing and used viral drugs permits the conclusion to be made that they can increase resistance of... 

Reacting this with sodium methoxide leads to the formation of an epoxide— 9-(2, 3 -anhydro- 8-luxofuranosyl)adenine (36.1.9). Finally, heating this epoxide with sodium acetate or benzoate opens the epoxide ring in the dimethylformamide-water system to make the corresponding dihydroxy derivative, vidarabine [12,13]. 

Another way of synthesis of vidarabine that was developed later consists of alkylating of 6-benzamidopurine with 2,3,5-tn-(9-benzyl-D-arabinofuranosyl chloride using sodium in liquid ammonia. This simultaneously iV-debenzylates the sixth position of the purine system and fulfil 0-debenzylation of hydroxyl groups of the furanosyl fragment of the molu-cule, giving vidarabine [14]. 

Epithelial keratitis that has not responded clinically to topical idoxuridine, or when ocular toxicity or hypersensitivity to idoxuridine has occurred. In a smaller number of patients resistant to topical vidarabine, trifluridine was also effective. 

Vidarabine (adenine arabinoside, ara-A) is phos-phorylated in the cell to the triphosphate derivative which blocks DNA synthesis by inhibiting DNA polymerase. It is indicated for infections with herpes simplex virus and varicella-zoster however its use has to a large extend been surpassed by aciclovir. It is administered topically or intravenously. It is inactivated rapidly by adenosine deaminase which for systemic use necessitates constant infusion of the drug. Vidarabine is the least toxic of the purine analogues. Nausea and vomiting are the most frequent adverse effects and neurotoxicity may occur. 

Hudarabine phosphate is a fluorinated nucleotide analog of the antiviral agent vidarabine. Its cytotoxicity is not well understood. It is rapidly dephospho-rylated at the cell membrane level and then rephos-phorylated intracellularly by deoxycytidine kinase to the active triphosphate derivative. It inhibits DNA polymerase and DNA primase. It is also incorporated into DNA and RNA. Hudarabine is administered intravenously by infusion over 30-120 min. It is eliminated by renal excretion with a terminal half life 10 hours. Adverse effects include myelosuppres-sion, nausea, vomiting, chills and fever. The number of CD4 positive cells is reduced and the incidence of opportunistic infections is increased. 

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