Ацикловир

As it is evident from the chemical structure, acyclovir looks like a nucleoside analog of guanosine in side chain of which, instead of the traditional cyclic sugar residue a 2-hydroxyethoxymethyl acyclic side chain is present. Acyclovir possesses antiviral activity with respect to types 1 and 2 of herpes simplex, shingles virus, Epstein–Barr virus, and cytomegalovirus.

white to light yellow crystal powder

Acyclovir (Zovirax) is a synthetic purine analog derived from guanine. It exerts its effects on the herpes simplex virus (HSV) and varicella-zoster virus by interfering with DNA synthesis through phosphorylation by viral thymidine kinase and subsequent inhibition of viral DNA polymerase, thereby inhibiting viral replication. It is effective against HSV-1 and 2, varicella-zoster virus, Epstein-Barr virus, herpesvirus simiae, and cytomegalovirus. Acyclovir may be administered intravenously, orally, or topically.

ChEBI: An oxopurine that is guanine substituted by a (2-hydroxyethoxy)methyl substituent at position 9.

Acyclovir (Zovirax) is a synthetic purine analog derived from guanine. It exerts its effects on the herpes simplex virus (HSV) and varicella-zoster virus by interfering with DNA synthesis through phosphorylation by viral thymidine kinase and subsequent inhibition of viral DNA polymerase, thereby inhibiting viral replication. It is effective against HSV-1 and 2, varicella-zoster virus, Epstein-Barr virus, herpesvirus simiae, and cytomegalovirus. Acyclovir may be administered intravenously, orally, or topically.
Acyclovir (400 mg PO b.i.d. or 200 mg PO five times a day) or other antiviral antibiotics can suppress herpes-associated EM. It is of no value once the EM has started. Not all episodes of a herpes simplex recurrence are associated with EM, but in recurrent cases, a 6-month trial of suppressive therapy can be helpful.

Activity is restricted to viruses of the herpes group. Herpes simplex virus (HSV) types 1 and 2, simian herpes virus B and varicella zoster viruses (VZV) are susceptible to concentrations readily attainable in human plasma. The 50% inhibitory concentration (ID50) is 0.1 μmol for HSV-1 and HSV-2 and 3 μmol for VZV, concentrations much below those toxic to cells. Valaciclovir is metabolized to aciclovir, and has the same antiviral profile. Thymidine-kinase-negative HSV mutants and cytomegalovirus (CMV) do not code for thymidine kinase and are generally resistant. Although Epstein–Barr virus (EBV) may have reduced thymidine kinase activity, its DNA polymerase is susceptible to aciclovir triphosphate and shows intermediate susceptibility. Human herpes viruses 6 and 7 are less susceptible than EBV.

Mutations in HSV that involve deficient thymidine kinase or an altered substrate are most common; alterations in the DNA polymerase gene also result in resistance. Resistant mutants may be found in wild virus populations; mutants lacking thymidine kinase activity may be readily induced by passage of HSV in the presence of the drug. Resistant strains have mostly been reported in immunocompromised patients, are generally thymidine-kinase negative, and have decreased virulence. Resistant mutants that retain thymidine kinase activity appear to retain virulence. Emergence of resistant HSV strains is less frequent in immunocompetent patients, occurring in about 2% of those receiving prolonged treatment.

Acyclovir, 9-[2-(hydroxyethoxy)methyl]-9H-guanine (Zovirax),is the most effective of a series of acyclic nucleosidesthat possess antiviral activity. In contrast with true nucleosidesthat have a ribose or a deoxyribose sugar attached to apurine or a pyrimidine base, the group attached to the basein acyclovir is similar to an open chain sugar, albeit lackingin hydroxyl groups. The clinically useful antiviral spectrumof acyclovir is limited to herpesviruses. It is most active (invitro) against HSV type 1, about two times less against HSVtype 2, and 10 times less potent against varicella–zostervirus (VZV).
The ultimate effect of acyclovir is the inhibition of viralDNA synthesis. Transport into the cell and monophosphorylationare accomplished by a thymidine kinase that is encodedby the virus itself.The affinity of acyclovir for the viralthymidine kinase is about 200 times that of the correspondingmammalian enzyme.
use: oral and parenteral. Oral acyclovir is used in the initialtreatment of genital herpes and to control mild recurrentepisodes. It has been approved for short-term treatment ofshingles and chickenpox caused by VZV. Intravenous administrationis indicated for initial and recurrent infectionsin immunocompromised patients and for the prevention andtreatment of severe episodes. The drug is absorbed slowlyand incompletely from the GI tract, and its oral bioavailabilityis only 15% to 30%. Nevertheless, acyclovir is distributedto virtually all body compartments.

A synthetic acyclic purine nucleoside analog of the natural nucleoside 2′ deoxyguanosine, formulated for oral and topical use, and as the sodium salt for intravenous infusion. Valaciclovir (the l-valyl ester) is a prodrug formulation supplied as the hydrochloride for oral use.

Antiviral agent, active against herpes simplex viruses HSV-1 and HSV-2 (EC 50 values are 0.85 and 0.86 μ M respectively). Interferes with viral DNA polymerization through competitive inhibition with guanosine triphosphate. Induces apoptosis in cells transfected with HSV-TK (suicidal gene therapy).

Aciclovir
Herpes simplex keratitis
Chickenpox and herpes zoster
Herpes simplex encephalitis and neonatal herpes
Prophylaxis of HSV infections in the severely immunocompromised
Valaciclovir
Herpes zoster and genital HSV infections