Antiviral drugs,

The antiviral agent foscamet (trisodium phosphonoformate) has been measured in plasma by HPLC using an ODS-modified silica column with ED. Pettersson et al used PGEs (Ei +0.75, E2 +0.90 V vs Pd). The eluent was methanol-aq. phosphate buffer (43 mmol L , pH 6.8) (25 + 75) containing tetrahexylammonium hydrogen sulfate (ImmolL ). Sample preparation involved ultrafiltration and 

Historically, the development of antiviral drugs has been slow when compared with the development of other antimicrobial drugs. This was probably because the majority of viral infections are eliminated by the host s immune system. With the advent of the HIV and acquired immunodeficiency syndrome (AIDS) that follows infection with HIV, many new antiviral drugs have been introduced since the end of the 1990s. As more is known about how viruses replicate inside cells and how they affect cell function, then no doubt more antiviral dmgs will be developed. 

Antiviral drugs have been developed that work by the following mechanisms  

Resistance can occur through a number of consequences of viral mutation. There may be reduced phosphorylation of the dmg (for example with nucleoside analogues), alteration of viral enzyme targets (for example with reverse transcriptase inhibitors), or alteration of target channel protein (for example with amantadine). 

These synthetic compounds resemble the natural nucleotides of viral DNA or RNA. They are phosphorylated in infected cells and then compete with the normal nucleotides for incorporation into viral DNA or RNA. This results in irreversible inhibition of viral polymerase (the enzyme that sticks nucleotides together to form DNA/RNA). 

Aciclovir is an analogue of guanosine nucleoside. It is used to treat herpes infections. 

It has been found that viruses (Appendix 10) utilize a number of virus specific enzymes during replication. These enzymes and the processes they control are significantly different from those of the host cell to make a useful target for medicinal chemists. Consequently, antiviral drugs usually act by either inhibiting viral nucleic acid synthesis, inhibit attachment to and penetration of the host cell or inhibit viral protein synthesis. 

M ore than 200 viruses have been identified as capable of producing disease Acute viruses, such as the common cold, have a rapid onset and quick recovery. Chronic viral infections, such as acquired immunodeficiency syndrome (AIDS), have recurrent episodes of exacerbations (increases in severity of symptoms of the disease) and remissions (periods of partial or complete disappearance of the signs and symptoms). Display 14-1 describes the viruses discussed in this chapter. 

Viruses can reproduce only within a living cell. A virus consists of either DNA or RNA surrounded by a protein shell. The virus is capable of reproducing only when it 

Lemon balm isa perennial herb with heart-shaped leaves that has been used for hundreds of years. Its scientific name is Melissa officinalis. Traditionally the herb has been used for Graves disease (see Chap. 51), asa sedative, arrtispasmodic, and an antiviral agent. When used topically, lemon balm has antiviral activity against herpes simplex virus(HSM). No adverse reactions have been reported when lemon balm is used topically. 

Although infections caused by a virus are common, antiviral drugp have limited use because they are effective against only a small number of specific viral infections. 

General uses of the antiviral dragp include the treatment of  

Viruses are small infective agents consisting essentially of nucleic acid (either RNA or DNA enclosed in a protein coat). Some viruses contain additional lipoproteins, which may contain antigenic viral glycoproteins. Viruses are intracellular parasites with no metabolic machinery of their own. To replicate, they must attach to and enter the living host cell animal, plant, or bacteria and use its metabolic process. 

Specific uses for the antiviral dm are listed in the Summary Drug Table Antiviral Dru.  

Viruses are obligate parasites having the operational characteristics of an exogenous submicroscopie unit capable of multiplication only inside specific cells. 

The size range is eonsiderable, ranging from an approximate diameter of 200 micrometers ( im) vaeeinia down to 10 ( lm) for foot and mouth disease. They can be seen and identified-only with the aid of an eleetron microscope. 

In general, viruses are essentially made up of a nucleic acid core having either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) that provides the genetic material and also forms the basis for classification of viruses. 

The viruses may be conceived as particles attaching themselves to particular receptors of the succeptible cells. These receptors may be chemical configurations that combine with either viruses or allied substances of similar composition. After due attachment the viruses gain entry into the cell and subsequently multiply. Thus the newly constituted viruses are eventually realised from the cell to paraciticize other cells of the host. In such transformation the metabolic activity of the host cell is modified in some manner. 

A number of diseases are caused by different types of viruses which are enumerated briefly as 

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Antiviral drug Antivitamins Antiwear agents Antiwear treatment Anto3 "E" [61931-82-6] Anto3 "H" [101-72-4] Antoine equation... 

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... 

Picornaviruses construct their shells from 60 copies each of three different polypeptide chains. These 180 subunits are arranged within the shell in a manner very similar to the 180 identical subunits of bushy stunt virus. In some picornaviruses there are protrusions around the fivefold axes, which are surrounded by deep "canyons." In rhinoviruses, the canyons form the virus s attachment site for protein receptors on the surface of the host cells, and they are adjacent to cavities that bind antiviral drugs. 

Although the term nucleoside was once limited to the compounds in Table 28.2 and a few others, cunent use is more permissive. Pyrimidine derivatives of D-arabinose, for exfflnple, occur in the free state in certain sponges and are called spongonticleosides. The powerful antiviral drug ribavirin, used to treat hepatitis C and Lassa fever, is a synthetic nucleoside analog in which the base, rather than being a pyrimidine or purine, is a triazole. 

Viruses are small infectious agents composed of a nucleic acid genome (DNA or RNA) encased by structural proteins and in some cases a lipid envelope. They are the causative agents of a number of human infectious diseases, the most important for public health today being acquired immunodeficiency syndrome (AIDS), hepatitis, influenza, measles, and vituses causing diarrhoea (e.g., rotavirus). In addition, certain viruses contribute to the development of cancer. Antiviral drugs inhibit viral replication by specifically targeting viral enzymes or functions and are used to treat specific virus-associated diseases. 

Antiviral Drugs. Figure 1 Basic steps of viral replication (A) binding, (B) entry, (C) genome replication, (D) gene expression, (E) assembly, (F) release. 

Mechanisms of Action of Currentiy Used Antiviral Drugs... 

Antiviral Drugs. Figure 2 Mechanism of action of chain-terminating nucleoside analogues. 

Antiviral Drugs Viral Proteases Chemokine Receptors... 

Calpains Viral Proteases Antiviral Drugs Non-viral Peptidases... 

Hsu JT, Wang HC, Chen GW et al (2006) Antiviral drug discovery targeting to viral proteases. Curr Pharm Des 12 1301-1314... 

Discuss the uses, general drug action, adverse reactions, contraindications, precautions, and interactions of antiviral drugs. 

Discuss important preadministration and ongoing assessment activities the nurse should perform on the patient receiving an antiviral drug. 

List some nursing diagnoses particular to a patient taking an antiviral drug. 

Discuss ways to promote an optimal response to therapy, how to manage adverse reactions, and special considerations to keep in mind when educating the patient and the family about the antiviral drugs. 

Because there are a limited number of antiviral drug s and more than 200 viral diseases, the primary health care provider may decide to prescribe an antiviral drug for an unlabeled use even though documentation of its effectiveness is lacking. Approval by the Food and Drug Administration (FDA) is necessary for a drug to be prescribed. On occasion, the use of a drug for a specific dis-... 

Antiviral drugs are given systemically or as topical dragp. When used systemically these dm may be administered orally or intravenously (IV). Rapid IV administration can result in crystalluria (presence of crystals in the urine). The most common adverse reactions when these drugp are administered systemically... 

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