THM 1) The three anti-viral drugs available for the treatment of herpes zoster are acyclovir, famciclovir and valaciclovir.
THM 2) Oral acyclovir 800 mg five times a day for 7 days, famciclovir 500 mg three times a day for 7 days and valaciclovir 1 gm three times a day for 7 days reduce acute pain and incidence & duration of post-herpetic neuralgia in patients who are treated within 72 hours of rash onset.
THM 3)The most common adverse effects are nausea, vomiting, diarrhea and headache.
The dose should be adjusted for renal insufficiency.
THM 4) Giving anti-viral drugs after 72 hours of onset of rash is practically useless.
An exception to the 72 hour threshold for treatment is made for patients who have opthalmic zoster, patients who continue to have new vesicle formation and in immunocompromised patients eg: in Aids.
THMs on ‘PAIN MANAGEMENT IN ACUTE ZOSTER:
THM 1) Paracetamol and NSAIDs can be used in acute zoster. They have limited efficacy and hence will be useful in mildly symptomatic patients.
THM 2) TCAs including amitriptyline and nortryptiline are useful in acute zoster though they take time to show benefit.
THM 3) There is questionable benefit in pain of acute zoster with anticonvulsants like gabapentin and these should not be used.
THM 4) Tramadol and Tapentadol are both effective as pain relievers with greater potency than paracetamol/NSAIDs and quicker action than TCAs.
THM 5) Local agents like lignocaine and capsaicin should not be used.
THM 6) Oral steroids have a role in improving symptoms (see below).
THM 7) The agents that have greatest benefit in reducing intensity and duration of pain are the antiviral agents; if started within 72 hours. Locally applied acyclovir has no value.
STEROIDS IN ACUTE ZOSTER –
Steroids started with an antiviral drug may help resolve rash and acute pain more rapidly. Am quoting below a paragraph from Harrison’s. Personally, i have never used steroids in acute zoster.
“In one study, glucocorticoid therapy administered early in the course of localized herpes zoster significantly accelerated such quality-of-life improvements as a return to usual activity and termination of analgesic medication. The dose of prednisone administered orally was 60 mg/d on days 1-7, 30 mg/d on days 8-14, and 15 mg/d on days 15-21. This regimen is appropriate only for relatively healthy elderly persons with moderate or severe pain at presentation.”