Aciclovir 800mg Tablets (Ramsay Hunt Syndrome / Herpes Zoster Oticus)

SOURCE: eMC UK SPC, productName 'Aciclovir 200 mg Tablets' (https://www.medicines.org.uk/emc/product/4334/smpc), §4.2. VERBATIM: 'Treatment of varicella and herpes zoster infections: 800 mg Aciclovir should be taken five times daily at approximately four-hourly intervals, omitting the night time dose. Treatment should continue for seven days.' STRENGTH CAVEAT: the fetched SPC is the 200 mg tablet product, although its §4.2 states the 800 mg zoster regimen literally — confirm against the 800 mg tablet SPC before publishing. INDICATION CAVEAT: the SPC does not name Ramsay Hunt syndrome or herpes zoster oticus anywhere; the regimen above is the generic herpes zoster regimen and the clinician must confirm it is the one intended for this page. TIMING: 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 onset of the rash. IMMUNOCOMPROMISED / IMPAIRED ABSORPTION: 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. OTHER INDICATIONS IN THE SAME SPC (not this page's indication): treatment of herpes simplex — 200 mg five times daily at approximately four hourly intervals omitting the night time dose for 5 days, extended in severe initial infections, and the dose can be doubled to 400 mg in severe immunocompromise or impaired gut absorption; suppression of herpes simplex in immunocompetent patients — 200 mg four times daily at approximately six-hourly intervals, or 400 mg twice daily at approximately twelve-hourly intervals, with titration down to 200 mg three times daily or twice daily, some patients may experience break-through infection on total daily doses of 800 mg, and therapy should be interrupted periodically at intervals of six to twelve months in order to observe possible changes in the natural history of the disease; prophylaxis of herpes simplex in immunocompromised patients — 200 mg four times daily at approximately six-hourly intervals (doubled to 400 mg in severe immunocompromise or impaired gut absorption), duration determined by the period at risk. ELDERLY: the possibility of renal impairment must be considered and the dosage adjusted accordingly; maintain adequate hydration on high oral doses. PAEDIATRIC — NOT carried into paedDose: the SPC states 'No specific data are available on the suppression of herpes simplex infections or the treatment of herpes zoster infections in immunocompetent children.' The only per-kg figure in this SPC belongs to the treatment of VARICELLA, not zoster — 'Dosing may be more accurately calculated as 20 mg/kg bodyweight (not to exceed 800 mg) Aciclovir four times daily', with fixed bands for varicella of 800 mg four times daily at 6 years and over, 400 mg four times daily at 2 to 5 years and 200 mg four times daily under 2 years, for five days. It has deliberately NOT been structured into paedDose because it is a different indication from this page and would otherwise be read as a paediatric zoster regimen. For treatment and prophylaxis of herpes simplex, children aged two years and over should be given adult dosages and children below the age of two years half the adult dose; for neonatal herpes virus infections intravenous aciclovir is recommended. Oral aciclovir should be used in the paediatric population mainly for non-severe skin and mucosa HSV infections; IV aciclovir should be used for neonatal HSV and severe HSV infections in immunocompromised children (§4.4). Verify all under-18 dosing against a children's formulary. No maximum dose for herpes zoster is stated anywhere in §4.2, so no maxDose is asserted in this draft.