Keep out of reach of children.
Read the directions carefully before use.
For prescription only.
QUALITATIVE AND QUANTITATIVE COMPOSITION
Active ingredient
Acyclovir ........................ 800 mg
Excipients q.s …………. 1 tablet
Tablet.
Product description: A pink, capsule-shaped tablet, scored on one side, imprinted on the other side, having undamaged edges.
Box of 3 blisters x 10 tablets.
Pharmacotherapeutic group: Direct acting antivirals, Nucleosides and nucleotides excl. reverse transcriptase inhibitors. ATC code: J05AB01.
Acyclovir is a synthetic purine nucleoside analogue with in vitro and in vivo inhibitory activity against human herpes viruses, including herpes simplex virus (HSV) types I and II and varicella zoster virus (VZV). The inhibitory activity of acyclovir for HSV I and HSV II and VZV is highly selective. The enzyme thymidine kinase (TK) of normal, uninfected cells does not use Acyclovir effectively as a substrate, hence toxicity to mammalian host cells is low; however, TK encoded by HSV and VZV converts acyclovir to acyclovir monophosphate, a nucleoside analogue which is further converted to the diphosphate and finally to the triphosphate by cellular enzymes. Acyclovir triphosphate interferes with the viral DNA polymerase and inhibits viral DNA replication with resultant chain termination following its incorporation into the viral DNA.
Prolonged or repeated courses of acyclovir in severely immuno-compromised individuals may result in the selection of virus strains with reduced sensitivity, which may not respond to continued acyclovir treatment. Most of the clinical isolates with reduced sensitivity have been relatively deficient in viral TK, however, strains with altered viral TK or viral DNA polymerase have also been reported. In vitro exposure of HSV isolates to acyclovir can also lead to the emergence of less sensitive strains. The relationship between the in vitro-determined sensitivity of HSV isolates and clinical response to acyclovir therapy is not clear.
There have been no studies to investigate the effect of acyclovir on driving performance or the ability to operate machinery. A detrimental effect on such activities cannot be predicted from the pharmacology of the active substance, but the adverse event profile should be borne in mind.
Pregnancy
The use of acyclovir should be considered only when the potential benefits outweigh the possibility of unknown risks.
A post-marketing acyclovir pregnancy registry has documented pregnancy outcomes in women exposed to any formulation of acyclovir. The registry findings have not shown an increase in the number of birth defects amongst acyclovir exposed subjects compared with the general population, and any birth defects showed no uniqueness or consistent pattern to suggest a common cause. Systemic administration of acyclovir in internationally accepted standard tests did not produce embryotoxic or teratogenic effects in rabbits, rats or mice. In a non-standard test in rats, foetal abnormalities were observed but only following such high subcutaneous doses that maternal toxicity was produced. The clinical relevance of these findings is uncertain.
Caution should however be exercised by balancing the potential benefits of treatment against any possible hazard.
Breast-feeding
Following oral administration of 200 mg acyclovir five times a day, Acyclovir has been detected in breast milk at concentrations ranging from 0.6 to 4.1 times the corresponding plasma levels. These levels would potentially expose nursing infants to acyclovir dosages of up to 0.3 mg/kg/day. Caution is therefore advised if acyclovir is to be administered to a nursing woman.
Fertility
There is no information on the effect of acyclovir on human female fertility.
In a study of 20 male patients with normal sperm count, oral acyclovir administered at doses of up to 1g per day for up to six months has been shown to have no clinically significant effect on sperm count, motility or morphology.
Acyclovir is eliminated primarily unchanged in the urine via active renal tubular secretion. Any drugs administered concurrently that compete with this mechanism may increase acyclovir plasma concentrations. Probenecid and cimetidine increase the AUC of acyclovir by this mechanism, and reduce acyclovir renal clearance. Similarly increases in plasma AUCs of acyclovir and of the inactive metabolite of mycophenolate mofetil, an immunosuppressant agent used in transplant patients have been shown when the drugs are co-administered. However no dosage adjustment is necessary because of the wide therapeutic index of acyclovir.
An experimental study on five male subjects indicates that concomitant therapy with acyclovir increases AUC of totally administered theophylline with approximately 50%. It is recommended to measure plasma concentrations during concomitant therapy with acyclovir.
The frequency categories associated with the adverse events below are estimates. For most events, suitable data for estimating incidence were not available. In addition, adverse events may vary in their incidence depending on the indication.
The following convention has been used for the classification of undesirable effects in terms of frequency: Very common ≥1/10, common ≥1/100 and <1/10, uncommon ≥1/1000 and <1/100, rare ≥1/10,000 and <1/1000, very rare <1/10,000.
Blood and lymphatic system disorders
Very rare: Anaemia, leukopenia, thrombocytopenia.
Immune system disorders
Rare: Anaphylaxis.
Psychiatric and nervous system disorders
Common: Headache, dizziness.
Very rare: Agitation, confusion, tremor, ataxia, dysarthria, hallucinations, psychotic symptoms, convulsions, somnolence, encephalopathy, coma.
The above events are generally reversible and usually reported in patients with renal impairment or with other predisposing factors.
Respiratory, thoracic and mediastinal disorders
Rare: Dyspnoea.
Gastrointestinal disorders
Common: Nausea, vomiting, diarrhoea, abdominal pains.
Hepato-biliary disorders
Rare: Reversible rises in bilirubin and liver related enzymes.
Very rare: Hepatitis, jaundice.
Skin and subcutaneous tissue disorders
Common: Pruritus, rashes (including photosensitivity).
Uncommon: Urticaria. Accelerated diffuse hair loss. Accelerated diffuse hair loss has been associated with a wide variety of disease processes and medicines, the relationship of the event to acyclovir therapy is uncertain.
Rare: Angioedema
Renal and urinary disorders
Rare: Increases in blood urea and creatinine.
Very rare: Acute renal failure, renal pain.
Renal pain may be associated with renal failure and crystalluria.
General disorders and administration site conditions
Common: Fatigue, fever.
Please inform your doctor of all undesirable effects upon drug administration.
Acyclovir is only partly absorbed in the gastrointestinal tract.
Patients have ingested overdoses of up to 20 g acyclovir on a single occasion, usually without toxic effects. Accidental, repeated overdoses of oral acyclovir over several days have been associated with gastrointestinal effects (such as nausea and vomiting) and neurological effects (headache and confusion).
Management: Patients should be observed closely for signs of toxicity. Haemodialysis significantly enhances the removal of acyclovir from the blood and may, therefore, be considered a management option in the event of symptomatic overdose.
Store in dry places, not exceeding 30oC, protect from light.
Use in patients with renal impairment and in elderly patients
Acyclovir is eliminated by renal clearance, therefore the dose must be adjusted in patients with renal impairment. Elderly patients are likely to have reduced renal function and therefore the need for dose adjustment must be considered in this group of patients. Both elderly patients and patients with renal impairment are at increased risk of developing neurological side effects and should be closely monitored for evidence of these effects. In the reported cases, these reactions were generally reversible on discontinuation of treatment. Prolonged or repeated courses of acyclovir in severely immune-compromised individuals may result in the selection of virus strains with reduced sensitivity, which may not respond to continued acyclovir treatment.
Hydration status: Care should be taken to maintain adequate hydration in patients receiving high doses of acyclovir.
The risk of renal impairment is increased by use with other nephrotoxic drugs.
The data currently available from clinical studies is not sufficient to conclude that treatment with acyclovir reduces the incidence of chickenpox-associated complications in immunocompetent patients.
Excipients
Wheat starch in this medicine contains only very low levels of gluten and is very unlikely to cause problems if you have coeliac disease. If you have wheat allergy, you should not take this medicine.
Ponceau may cause allergic reactions.
Medskin Clovir 800 is indicated for the treatment of varicella (chickenpox) and herpes zoster (shingles) infections (excluding neonatal HSV and severe HSV infections in immunocompromised children).
Medskin Clovir 800 is recommended for children over the age of 6.
Hypersensitivity to aciclovir or valaciclovir, or to any of the excipients in this formulation.
METHOD OF ADMINISTRATION
Tablets are for oral administration and may be dispersed in a minimum of 50 ml of water or swallowed whole with a little water. Ensure that patients on high doses of acyclovir are adequately hydrated.
POSOLOGY
Dosage in adults
Treatment of varicella and herpes zoster infections: 800 mg acyclovir should be taken five times daily at approximately four-hourly intervals, omitting the nighttime dose. Treatment should continue for seven days.
In severely immunocompromised patients (e.g. after marrow transplant) or in patients with impaired absorption from the gut, consideration should be given to intravenous dosing.
Dosing should begin as early as possible after the start of an infection: Treatment of herpes zoster yields better results if initiated as soon as possible after the onset of the rash. Treatment of chickenpox in immunocompetent patients should begin within 24 hours after the onset of the rash.
Dosage in children
Treatment of varicella infections
6 years and over: 800 mg acyclovir four times daily. Treatment should continue for five days.
No specific data are available on the treatment of herpes zoster infections in immunocompetent children.
For treatment of neonatal herpes virus infections, intravenous acyclovir is recommended.
Dosage in the elderly
The possibility of renal impairment in the elderly must be considered and the dosage should be adjusted accordingly (see Dosage in renal impairment below).
Adequate hydration of elderly patients taking high oral doses of acyclovir should be maintained.
Dosage in renal impairment
Caution is advised when administering acyclovir to patients with impaired renal function. Adequate hydration should be maintained.
In the treatment of herpes zoster infections it is recommended to adjust the dosage to 800 mg acyclovir twice daily at approximately twelve-hourly intervals for patients with severe renal impairment (creatinine clearance less than 10 ml/minute) and to 800 mg acyclovir three times daily at intervals of approximately eight hours for patients with moderate renal impairment (creatinine clearance in the range of 10 - 25 ml/minute).
Or as directed by the physician.
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