Aciclovir Reneval, tablets 400 mg 20 pcs

Pharmacotherapeutic group: antiviral drug.

ATX code: J05AB01

Pharmacological properties

Pharmacodynamics

Acyclovir is a synthetic purine nucleoside analog that has the ability to inhibit in vitro and in vivo human herpes viruses, including herpes simplex virus (HPV) types 1 and 2, varicella zoster virus (Varicella zoster virus (VZV)), Epstein-Barr virus (EBV) and cytomegalovirus (CMV). In cell culture acyclovir has the most pronounced antiviral activity against HPV-1, followed in descending order of activity by: HPV-2, VZV, EBV and CMV. </The inhibitory effect of acyclovir against herpes viruses (HAV-1, HAV-2, VHF, EBV and CMV) is highly selective. Acyclovir is not a substrate for thymidine kinase enzyme of uninfected cells, so acyclovir is slightly toxic for mammalian cells. Thymidine kinase of cells infected with HPV, EVD, EBV and CMV converts acyclovir into acyclovir monophosphate, a nucleoside analog, which is then sequentially converted into diphosphate and triphosphate under the action of cellular enzymes. Incorporation of acyclovirtriphosphate into the chain of viral DNA and subsequent chain breakage block further replication of viral DNA.

In patients with severe immunodeficiency, prolonged or repeated courses of acyclovir therapy may lead to the emergence of resistant strains, so further treatment with acyclovir may not be effective. Most isolated strains with reduced sensitivity to acyclovir showed relatively low levels of viral thymidine kinase, impaired viral thymidine kinase structure or DNA polymerase. Exposure of herpes simplex virus (HPV) strains to acyclovir in vitro can also lead to the formation of less sensitive strains. No correlation has been established between the sensitivity of herpes simplex virus (HPV) strains to acyclovir in vitro and the clinical efficacy of the drug.

Pharmacokinetics

Intake

Acyclovir is only partially absorbed from the intestine. After administration of 200 mg of acyclovir every 4 hours, the mean maximum equilibrium plasma concentration (Css_max) was 3.1 µM (0.7 µg/mg), and the mean equilibrium minimum plasma concentration (Css_min) was 1.8 µM (0.4 µg/mL). When 400 mg and 800 mg of acyclovir were given every 4 hours, Css_max was 5.3 µM (1.2 µg/mL) and 8 µM (1.8 µg/mL), respectively, and Css_min was 2.7 µM (0.6 µg/mL) and 4 µM (0.9 µg/mL), respectively.

Distribution

The concentration of acyclovir in cerebrospinal fluid is approximately 50% of its concentration in plasma.

Aciclovir binds only slightly (9-33%) with plasma proteins, therefore drug interactions due to displacement from binding sites with plasma proteins are unlikely.

Elimation

In adults after oral administration of acyclovir the elimination half-life from the blood plasma is about 3 hours. Most of the drug is excreted unchanged by the kidneys. Renal clearance of acyclovir significantly exceeds creatinine clearance, which indicates excretion of acyclovir not only by glomerular filtration, but also by tubular secretion. The main metabolite of acyclovir is 9-carboxymethoxymethylguanine, which accounts for about 10-15% of the administered dose of the drug in the urine. When administering acyclovir 1 hour after taking 1 g of probenecid, the half-life of acyclovir and AUC (area under the pharmacokinetic curve “concentration-time”) increased by 18% and 40%, respectively.

Special patient groups

In patients with chronic renal failure the half-life of acyclovir averaged 19.5 hours. With hemodialysis, the average half-life of acyclovir was 5.7 hours. The plasma concentration of acyclovir decreased by approximately 60% during dialysis.

In elderly patients, acyclovir clearance decreases with age in parallel with a decrease in creatinine clearance, but the half-life of acyclovir changes only slightly.

The pharmacokinetic characteristics of both drugs were virtually unchanged when acyclovir and zidovudine were administered simultaneously to HIV-infected patients.

Indications

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Composition

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Synopsis

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Side effects

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