Idoxuridine and its features
Idoxuridine is a synthetic thymidine analogue. The drug is available as eye drops (known under the trade names Ofthan Idu and Kerecid).
Key characteristics:
- Indications: local therapy of herpetic keratitis and conjunctivitis.
- Regimen: requires extremely frequent administration — hourly during the day and every two hours at night.
- Limitations: contraindicated for systemic (resorptive) use due to marked toxicity.
- Side effects: contact dermatitis of the eyelids, allergic manifestations, and corneal opacity are possible.
Trifluridine
This drug is also a thymidine analogue and is intended for the same therapeutic tasks as idoxuridine.
To date, trifluridine has an important regulatory restriction: it is not officially registered in the Russian Federation.
Tromantadine for skin and mucous membranes
Tromantadine is available as a gel (trade name — Vira-MP Serol).
Key properties:
- Indications: treatment of herpetic eruptions on the skin and mucous membranes, including manifestations caused by herpes simplex virus (HSV), as well as shingles (herpes zoster).
- Pharmacokinetics: when applied topically, it practically does not penetrate into the systemic circulation.
- Side effects: limited exclusively to local allergic reactions such as itching, redness, swelling, and pain at the application site.
Briefly: answers to topical questions
What is the mechanism of action of idoxuridine at the molecular level?
Idoxuridine acts as a synthetic thymidine analogue belonging to the group of abnormal nucleosides. At the molecular level, its mechanism of action involves the disruption of viral nucleic acid synthesis. Due to high toxicity, the drug is not used systemically (resorptively), but exclusively for the local treatment of herpetic infections.
Which drugs belong to the group of topical antiherpetic agents?
The group of topical antiherpetic agents includes drugs available in forms for external use.
- Idoxuridine — eye drops indicated for the local treatment of keratitis and conjunctivitis.
- Trifluridine — a thymidine analogue for topical use.
- Tromantadine — a gel for the treatment of skin and mucosal lesions.
- Penciclovir — used topically (Fenistil Pencivir) for recurrent herpes simplex.
- Acyclovir — used as a 5% ointment as the drug of choice.
Which antiherpetic drugs are used to treat herpetic keratitis?
Specific antiviral agents and enzyme preparations are used to treat herpetic keratitis.
- Idoxuridine — eye drops indicated for the local treatment of keratitis and conjunctivitis of herpetic etiology.
- Trifluridine — an abnormal nucleoside used in ophthalmology (keratitis of herpetic and adenoviral etiology).
- Nucleases (ribonuclease, deoxyribonuclease) — enzymes used as antiviral agents for herpetic keratitis.
- Acyclovir and Valacyclovir — prescribed systemically for ocular herpes zoster accompanied by corneal involvement (keratitis).
Idoxuridine is instilled every hour during the day and every two hours at night, while tromantadine is applied as a gel without systemic absorption into the blood.
Class and exam questions
Why cannot idoxuridine be administered orally or via injection?
The drug exhibits high toxicity, which is why it is used exclusively topically.
What is the chemical structure of idoxuridine and trifluridine?
Both medicinal substances are synthetic thymidine analogues.
In what dosage form is tromantadine available, and does it absorb into the blood?
The drug is available as a gel and, when applied, practically does not penetrate into the systemic circulation.
What else to study on this topic
- Chemical structure of thymidine analogues
- Comparison of topical ophthalmic antiherpetic formulations
- Pharmacokinetic features of topical agents
- Toxicological profile of idoxuridine
- Spectrum of activity of tromantadine in herpes zoster
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