Medovir

Acyclovir.

Pharmacology: Acyclovir is an antiviral agent which is highly active in vitro against herpes simplex virus (HSV) types I and II and varicella zoster virus. Toxicity to mammalian host cells is low.
Acyclovir is phosphorylated after entry into herpes-infected cells to the active compound acyclovir triphosphate. The 1st step in this process is dependent on the presence of the viral-coded thymidine kinase. Acyclovir triphosphate acts as an inhibitor of and substrate for the herpes-specified DNA polymerase preventing further viral DNA synthesis without affecting normal cellular processes.

Treatment of herpes simplex virus infections of the skin and mucous membranes including initial and recurrent genital herpes.
Suppression (prevention of recurrences) of recurrent herpes simplex infections in immunocompetent patients.
Prophylaxis of herpes simplex infections in immunocompromised patients.
Treatment of herpes zoster infections.

Adults: Treatment of Herpes Simplex: 200 mg should be taken 5 times daily at approximately 4-hourly intervals omitting the nighttime dose. Treatment should continue for 5 days, but in severe initial infections, may have to be extended. In severely immunocompromised patients (eg, after marrow transplant) or in patients with impaired absorption from the gut, the dose can be doubled to 400 mg.
Dosing should begin as early as possible after the start of an infection. For recurrent episodes, this should preferably be during the prodromal period or when lesions 1st appear.
Suppression of Herpes Simplex: In immunocompetent patients, 200 mg should be taken 4 times daily at approximately 6-hourly intervals.
Many patients may be conveniently managed on a regimen of 400 mg taken twice daily at approximately 12-hourly intervals.
Dosage titration down to 200 mg taken 3 times daily at approximately 8-hourly intervals or even twice daily at approximately 12-hourly intervals, may prove effective.
Some patients may experience breakthrough infections on total daily doses of 800 mg.
Therapy should be interrupted periodically at intervals of 6-12 months, in order to observe possible changes in the natural history of the disease.
Prophylaxis of Herpes Simplex: In immunocompromised patients, 200 mg should be taken 4 times daily at approximately 6-hourly intervals. In severely immunocompromised patients (eg, after marrow transplant) or in patients with impaired absorption from the gut, the dose can be doubled to 400 mg or alternatively, IV dosing could be considered.
The duration of prophylactic administration is determined by the duration of the period at risk.
Treatment of Herpes Zoster: 800 mg should be taken 5 times daily at approximately 4-hourly intervals, omitting the nighttime dose. Treatment should continue for 7 days.
In severely immunocompromised patients (eg, after marrow transplant) or in patients with impaired absorption from the gut, consideration should be given to IV dosing.
Dosing should begin as early as possible after the start of an infection; treatment yields better results if initiated as soon as possible after onset of the rash.
Children: For treatment and prophylaxis of herpes simplex infections in the immunocompromised, children >2 years should be given adult dosages and children <2 years should be given ½ the adult dose.
No specific data are available on the suppression of herpes simplex infections or the treatment of herpes zoster infections in immunocompetent children.
Elderly: In the elderly, total acyclovir body clearance declines in parallel with creatinine clearance. Adequate hydration of elderly patients taking high oral doses of acyclovir should be maintained. Special attention should be given to dosage reduction in elderly patients with impaired renal function.
Renal Impairment: In the management of herpes simplex infections in patients with impaired renal function, the recommended oral dose will not lead to accumulation of acyclovir above levels that have been established safe by IV infusion. However, for patients with severe renal impairment (creatinine clearance <10 mL/min), an adjustment of dosage to 200 mg twice daily at approximately 12-hourly intervals is recommended.
In the treatment of herpes zoster infections, it is recommended to adjust the dosage to 800 mg twice daily at approximately 12-hourly intervals for patients with severe renal impairment (creatinine clearance <10 mL/min) and to 800 mg 3 or 4 times daily at intervals of approximately 6-8 hrs for patients with moderate renal impairment (creatinine clearance in the range 10-25 mL/min).

Symptoms: Acyclovir is only partly absorbed in the gastrointestinal tract. It is unlikely that serious toxic effects would occur if a dose of up to 5 g were taken on a single occasion. No data are available on the consequences of the ingestion of higher doses.
Single IV doses of up to 80 mg/kg have been inadvertently administered without adverse effects.
Treatment: Ingestion of doses of acyclovir in excess of 5 g warrants close observation of the patient. Acyclovir is dialyzable.

Hypersensitivity to acyclovir.

Carcinogenicity: Acyclovir was not found to be carcinogenic in long-term studies in the rat and the mouse.
Mutagenicity: The results of a wide range of mutagenicity test in vitro and in vivo indicate that acyclovir does not pose a genetic risk to man.
Impairment of Fertility: Largely reversible adverse effects on spermatogenesis in association with overall toxicity in rats and dogs have been reported only at doses of acyclovir greatly in excess of those employed therapeutically.
Two generation studies in mice did not reveal any effect of orally administered acyclovir on fertility.
There is no experience on the effect of Medovir on human female fertility.
Medovir has been shown to have no definitive effect upon sperm count, morphology or motility in man.
Use in pregnancy & lactation: Systemic administration of acyclovir did not produce embryotoxic or teratogenic effects in rabbits or rats.
Experience in humans is limited, so the use of acyclovir should be considered only when the potential benefits outweigh the possibility of unknown risks. Limited human data show that Medovir does pass into breast milk.

Systemic administration of acyclovir did not produce embryotoxic or teratogenic effects in rabbits or rats.
Experience in humans is limited, so the use of acyclovir should be considered only when the potential benefits outweigh the possibility of unknown risks. Limited human data show that Medovir does pass into breast milk.

Skin rashes have been reported in a few patients receiving Medovir; the rashes have resolved on withdrawal of the drug.
Gastrointestinal effects, including nausea, vomiting, diarrhoea and abdominal pains have been reported in some patients receiving Medovir.
Other events reported rarely in patients receiving oral formulations of acyclovir include mild, transient rises in bilirubin and liver-related enzymes, small increases in blood urea and creatinine, small decreases in haematological indices, headaches, mild reversible neurological reactions and fatigue.

Probenecid increases the acyclovir mean t_½ and area under the plasma concentration curve. Other drugs affecting renal physiology could potentially influence the pharmacokinetics of acyclovir. However, clinical experience has not identified other drug interactions with acyclovir.

Store below 25°C.

Antivirals

J05AB01 - aciclovir ; Belongs to the class of nucleosides and nucleotides excluding reverse transcriptase inhibitors. Used in the systemic treatment of viral infections.

POM