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Abstract:
This document is the Summary of Product Characteristics (SmPC) for Aciclovir 200 mg tablets, an antiviral medication effective against herpes viruses. It serves as a comprehensive guide for healthcare professionals on the safe and effective use of the drug. The document outlines the therapeutic indications, which include the treatment and suppression of herpes simplex virus (HSV) infections (e.g., cold sores, genital herpes) and the treatment of varicella zoster virus (VZV) infections (chickenpox and shingles).
Detailed dosing (posology) instructions are provided for adults, children, the elderly, and patients with renal impairment, highlighting the critical need for dose adjustment and adequate hydration, especially with high doses. Key warnings focus on the risk of renal impairment and neurological side effects, which are elevated in elderly patients and those with pre-existing kidney conditions. The text also covers potential drug interactions, use during pregnancy and lactation, a list of undesirable effects, and management of overdose. The pharmacological section explains that Aciclovir is a selective antiviral agent that inhibits viral DNA replication.
Aciclovir 200 mg Tablets: A Guide to Use, Dosage, and Safety
4.1 Therapeutic Indications: Aciclovir is an antiviral medication used to treat infections caused by the herpes simplex virus (HSV), such as cold sores and genital herpes, and the varicella-zoster virus (VZV), which causes chickenpox and shingles.
4.2 Posology (Dosage): Dosage varies significantly depending on the condition and patient:
Herpes Simplex Treatment: 200 mg five times daily for 5 days.
Herpes Simplex Suppression (prevention of recurrence): 200 mg four times daily, or 400 mg twice daily.
Chickenpox and Shingles Treatment: 800 mg five times daily for 7 days.
Special Populations: Doses must be reduced for children, the elderly, and patients with impaired kidney (renal) function. Maintaining adequate hydration is crucial for all patients on high doses.
4.3 Contraindications: The drug should not be used by individuals with a known hypersensitivity (allergy) to aciclovir or valaciclovir.
4.4 Special Warnings & The Risk with Alcohol:
Key Takeaway: The primary risk of taking Aciclovir is to the kidneys, not the liver. Aciclovir is cleared from the body by the kidneys.
For an otherwise healthy patient taking 200 mg five times daily, the main danger associated with heavy alcohol consumption is dehydration.
Dehydration impairs the kidneys' ability to filter and excrete the drug effectively. This can lead to the drug accumulating, increasing the risk of kidney damage (renal pain, crystalluria, or acute renal failure) and neurological side effects (e.g., confusion, agitation, headache).
Crucial Precaution: It is essential to maintain excellent hydration while taking Aciclovir, especially if consuming alcohol, to support kidney function and prevent complications.
4.5 Drug Interactions: Aciclovir can interact with other drugs that are also cleared by the kidneys (nephrotoxic drugs) or compete for excretion, such as probenecid and cimetidine, which may increase its concentration in the blood.
4.6 Use in Pregnancy and Breastfeeding: Aciclovir should only be used during pregnancy if the potential benefits justify the potential risks. The drug passes into breast milk, so caution is advised for nursing mothers.
Very Rare but Serious: Anemia, confusion, hallucinations, seizures, coma, acute renal failure, hepatitis, and jaundice. Neurological side effects are more common in patients with impaired renal function.
4.9 Overdose: Accidental overdose can lead to gastrointestinal effects (nausea, vomiting) and neurological symptoms (headache, confusion). In severe cases, haemodialysis may be used to remove the drug from the blood.
5.1 Pharmacodynamics (How it Works): Aciclovir is a highly selective antiviral. It is converted into its active form only inside virus-infected cells, where it interferes with viral DNA polymerase to stop the virus from replicating.
Medical Terms Glossary
AUC (Area Under the Curve): A term in pharmacokinetics that represents the total exposure of the body to a drug over time.
Contraindication: A specific situation in which a drug, procedure, or surgery should not be used because it may be harmful to the person.
Crystalluria: The presence of crystals in the urine, which can indicate a risk of kidney stones or renal damage.
Immunocompromised: Having an impaired immune system, making it harder for the body to fight infections and diseases.
Nephrotoxic: Damaging or destructive to the kidneys.
Pharmacodynamics: The study of what a drug does to the body.
Pharmacokinetics: The study of what the body does to a drug (absorption, distribution, metabolism, and excretion).
Posology: The branch of medicine concerned with the determination of appropriate doses of drugs.
Prophylaxis: Action taken to prevent disease.
Renal: Relating to the kidneys.
Teratogenic: An agent that can disturb the development of an embryo or fetus, potentially causing birth defects.