Cycloren

Cycloren (Aciclovir) is a synthetic antiviral drug
CLINICAL PHARMACOLOGY:
Cyloren is an antiviral agent that is highly active against herpes simplex virus (HSV) types I, II and varicella zoster virus in vitro, Aciclovir is phosphorylated after entry into herpes `infected cell to the active compound aciclovir triphosphate, which acts as an inhibitor and substrate for the herpes specified DNA polymerase, preventing further viral DNA synthesis without affecting normal cellular processes. Aciclovir is only partially absorbed from the gut. Mean steady state peak plasma concentrations following oral doses of 200mg of aciclovir administered four hourly were 0.68 mcg/ml and the equivalent trough plasma levels were 0.36 mcg/ml. Most of the drug is excreted unchanged by the kidney. Renal clearance of aciclovir is substantially greater than creatinine clearance, indicating that tubular secretion in addition to glomerular filtration, contributes to the renal elimination of the drug.
INDICATIONS:
Cycloren is indicated in the management of herpes simplex virus infections of the skin and mucous membranes including initial and recurrent genital herpes. Cycloren is indicated for the suppression (prevention of recurrences) of frequent and/or severe episodes of recurrent genital herpes or recurrent herpes simplex infections at other sites, in immune competent patients, who cannot be satisfactorily managed by intermittent treatment.Cycloren is also indicated for the prophylaxis of herpes simplex infections in immunocompromised patients.
CONTRAINDICATIONS:
Cycloren is contraindicated in patient known to be hypersensitive to aciclovir.
PRECAUTIONS:
Cycloren should be used with caution in those patients who have underlying neurologic abnormalities and those with serious renal, hepatic or electrolyte abnormalities or significant hypoxia.It should also be used with caution in patients who have manifested prior neurological reactions to cytotoxic drugs or those receiving concomitant intrathecal methotrexate or interferon. There are no adequate and well controlled studies of aciclovir in pregnant women. Aciclovir should not be used during pregnancy unless potential benefit justifies the potential risk to the fetus. Aciclovir concentrations have been documented in breast milk following oral administration of aciclovir.Caution should be exercised when administered to a nursing woman.
ADVERSE REACTIONS:
Skin rashes have been reported in a few patients receiving aciclovir tablets; the rashes have resolved on withdrawal of the drug. Gastrointestinal effects including nausea, vomiting, diarrhoea and abdominal pain have been reported in some patients receiving aciclovir. In double-blind, placebo-controlled trials the incidence of gastrointestinal events has not been found to differ between placebo and aciclovir recipients.Other events reported rarely in patients receiving oral formulations of aciclovir include mild, transient rises in bilirubin and liver related enzymes, small increase in blood urea and creatinine, small decreases in hematological indices, headache, mild reversible neurological reactions and fatigue.
DRUG INTERACTIONS:
Probenecid increases the aciclovir mean half-life and area under the plasma concentration curve.Other drugs affecting renal physiology could potentially influence the pharmacokinetics of aciclovir. However, clinical experience has not identified other drug interactions with aciclovir.
DOSAGE AND ADMINISTRATION:
For the treatment of Herpes simplex infections, the adult dose of Cycloren is 200mg 5 times daily for 5 days, approximately 4 hourly, omitting the night time dose. In severe initial infections, the treatment may have to be extended for more than 5 days. In severely immunocompromised patients with impaired absorption from the gut, the dose of Cycloren can be doubled to 400mg. For suppression or prophylaxis of herpes simplex infection in immunocompetent patients, a starting dose of 200mg Cycloren should be taken four times daily at approximately six hourly intervals or 400mg twice daily at approximately twelve-hourly intervals. Some patients may experience break-through infections on total daily doses of Cycloren 800mg.When indicated for suppression of herpes simplex infections, Cycloren therapy should be interrupted periodically at intervals of six to twelve months, in order to reassess suitability for continued suppression.
Dosage in children: Treatment of herpes simplex infections and prophylaxis of herpes simplex infections in immunocompromised: Children aged 2 years and over should be given adult dosages and children below 2 years should be given half the adult dose. Treatment should be continued for 5 days. Dosage in elderly: In elderly, total aciclovir body clearance declines along with creatinine clearance. Adequate hydration of elderly patients taking high oral doses of Cycloren should be maintained.
Dosage in renal impairment: In patients with severe renal impairment, an adjustment of dosage to 200mg Cycloren twice daily 12-hourly intervals is recommended.
OVERDOSAGE:
Aciclovir is only partly absorbed in the gastrointestinal tract. It is unlikely that serious toxic effects would occur if a dose of up to 5g were taken on a single occasion. No data are available on the consequences of the ingestion of higher doses: such an occurrence warrants close observation of the patient. Aciclovir is dialyzable.
PRESENTATION: Cycloren tablets are available in a strip of 10 tablets, each tablet containing aciclovir BP 200mg.
STORAGE:
Store below 30℃, protected from light and moisture.