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Herpes zoster — MSRA MCQ

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HardInfectious DiseasesHerpes zosterMSRA

A 78-year-old man is reviewed in general practice with a painful, unilateral vesicular eruption over the left T8 dermatome. The rash began 4 days ago and new vesicles have appeared this morning. He is afebrile, systemically well and has no facial rash, ocular symptoms, weakness, confusion or widespread lesions. He has stage 3b chronic kidney disease; his stable Cockcroft-Gault creatinine clearance is 38 mL/minute. He is not immunosuppressed, can maintain oral fluids and has no drug allergies. You diagnose uncomplicated herpes zoster. Which is the most appropriate management today?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: D — Prescribe oral valaciclovir 1 g twice daily for 7 days and advise adequate oral hydration

Explanation lettering: C = shown as A · E = shown as B · D = shown as C · B = shown as D · A = shown as E

This is uncomplicated localised thoracic shingles, with no ophthalmic, neurological, disseminated or systemic features requiring hospital assessment. Although antiviral treatment is most effective when started within 72 hours, UK primary-care guidance supports considering treatment up to 1 week after rash onset when new vesicles are continuing to form or the person is at increased risk of complications; both apply here. Valaciclovir is an appropriate oral antiviral, but its zoster dose must be adjusted for renal function. For a creatinine clearance of 30–49 mL/minute, the SmPC recommends 1 g twice daily. A 7-day course is appropriate in an immunocompetent adult. Adequate hydration is important because aciclovir, the active metabolite, is renally cleared and renal impairment increases toxicity risk. A uses the usual dose for creatinine clearance of at least 50 mL/minute and risks accumulation. C incorrectly treats 72 hours as an absolute cut-off despite ongoing vesicle formation. D is the dose for more severe renal impairment (creatinine clearance 10–29 mL/minute) and may undertreat. E would be appropriate for complicated, disseminated or severe zoster, but not for this stable patient with localised disease who can take oral treatment.

Reference: Valaciclovir 500 mg Film Coated Tablets - Summary of Product Characteristics (13 March 2024) — https://www.medicines.org.uk/emc/product/4349/smpc Varicella zoster/chicken pox - Herpes zoster/shingles (Antimicrobial) (2024) — https://www.rightdecisions.scot.nhs.uk/tam-treatments-and-medicines-nhs-highland/adult-therapeutic-guidelines/antimicrobial-guidance/skin-soft-tissue-antimicrobial/varicella-zosterchicken-pox-herpes-zostershingles-antimicrobial/