Analgesic treatment of acute HZ should follow the three-step WHO pain ladder, based on pain severity, and individual considerations:
- mild pain intensity – NSAIDs or other nonopioids
- moderate pain – nonopioids in combination with weak opioid analgesics
- severe pain – nonopioids combined with strong opioids, if needed.23
If a patient’s pain severity at baseline is moderate to severe or other risk factors for PHN are present, it is worth considering supplementing with an antidepressant (e.g. amitriptyline, nortriptyline; not a licensed indication) or antiepileptic (gabapentin, pregabalin) drug.23
Herpes zoster antiviral therapy
Three antiviral drugs (aciclovir, valaciclovir and famciclovir) have established efficacy in the treatment of acute HZ by accelerating the resolution of lesions, reducing viral shedding and decreasing the severity of acute pain. They also reduce the overall duration of acute HZ pain. Valaciclovir and famciclovir are usually preferred because of their better oral absorption, higher blood levels and easier dosing.24 Oral aciclovir does not reduce the incidence of PHN significantly and there is insufficient evidence to determine the effect of other antiviral treatments on PHN.17
Controlled trials of prednisone (in doses of 40 mg daily for seven days, tapering by 5 mg daily over the subsequent two weeks) have shown benefit, particularly for acute HZ pain and quality of life.25,26 In contrast, there is no evidence that corticosteroids reduce the incidence of PHN,25 nor the total duration of pain.27 Corticosteroids should not be used for acute HZ without concomitant administration of antiviral drugs, as they are immunosuppressive.
There is reasonable evidence that pharmacotherapy such as topical lidocaine patches, gabapentin, pregabalin, tricyclic antidepressants or opiates can reduce the pain burden from PHN.28-33 Opioids should not be considered for first-line therapy, given the uncertainty regarding long-term efficacy and concern about safety.34
PHN remains difficult to treat. Fewer than half the patients with PHN in clinical trials of available therapies have had a 50% or greater reduction in pain.14 In addition, adverse effects are common, particularly in older patients.14
The best protection against HZ is to boost an individual’s immunity by vaccinating with the HZ vaccine. The live attenuated HZ vaccine is currently the only vaccination available in Australia to prevent HZ. This vaccine is effective in preventing HZ and PHN. It is licensed in Australia for adults 50 years and over. It is recommended for immunocompetent adults aged 60 years and older and is funded under the National Immunisation Program (NIP) for those aged between 70 and 79 years. As 95% of young adults have had varicella infection it is not necessary to check immunity.
The efficacy of this vaccine was examined in the Shingles Prevention Study, a double-blind randomised-controlled trial conducted with more than 38,000 people over the age of 60 years.35 Subjects received a concentrated (14-fold) form of the live attenuated varicella (Oka strain) vaccine and were followed for a median of 3.1 years. This vaccine was shown to be both safe and efficacious, preventing HZ in 51% of subjects, preventing PHN in 66% of subjects and reducing the burden of illness (a measure of severity and duration of pain) by 61%.
Although the efficacy of the live attenuated HZ vaccine in preventing shingles was found to be reduced in people over the age of 70 years and waned further with increasing age, the beneficial effect of the vaccine on the severity of illness and the incidence of PHN was similar among older subjects.35,36
Subsequent follow-up studies suggested efficacy may wane, probably over five to eight years.36 This has led to suggestions that a booster may be necessary at 10 years, although there are no current international recommendations for this.
The HZ vaccine contains live, attenuated VZV and is therefore contraindicated in patients who are significantly immunocompromised. Disseminated HZ and death have occurred postvaccination in patients with malignant haematological disorders.37,38
Although anti-tumour necrosis factor biologics are listed as a contraindication to the live attenuated HZ vaccine, it appears safe in patients receiving these drugs.39 However, more studies are needed to define vaccine safety with other biologics and in moderately immunocompromised patients.