I have seen few cases of Shingles recently – both confirmed and false ones which have prompted me to look closer at the current recommended approach – to treat or to prevent? Shingles or herpes zoster is caused by a varicella-zoster virus (VZV), also known as human herpes virus 3 (HHV3). It is the same virus that causes chicken pox in kids. But in Shingles, it is a result of latent reactivation within the sensory ganglia of the nervous system.

Based on a review article by Gan et al, I will highlight some of the management pearls of Herpes Zoster and Post-herpetic neuralgia.  Herpes Zoster often affects adults older than 50 years old. Varicella zoster virus (VZV) is transmitted from person to person by direct contact, inhalation of aerosols from the vesicular fluid of skin lesions or infected respiratory tract secretions. Although one cannot transmit shingles from direct contact, individuals confirmed to have shingles should be isolated from others who have not had chicken pox or immunized against varicella.

The most common risk factors for shingles are:

  • immunosuppression
  • advancing age
  • malignancy
  • chronic kidney or lung disease
  • disorders of cell-mediated immunity (e.g. HIV, family history of zoster)

Acutely, Shingles can present with a painful vesicular rash with dermatomal distribution. Both the acute herpes zoster and subsequent post-herpatic neuralgia can have severe and debilitating effects on individuals.

The common clinical features of herpes zoster include prodromal pain and / or itching with eruption of painful vesicular rash in a dermatomal distribution.

Antiviral Treatment Options

Until recently, we only have the treatment options of antiviral agents:

  • Acyclovir 800mg po 5 times a day for 7-10 days (IV 10mg/kg/dose 8 hourly for 7 days in severe infection or immunocompromised states)
  • Valacyclovir 1000mg po TID for 7 days
    • LU code  159 – Herpes zoster in patients 50 years of age or older, up to 72 hours* after appearance of lesions. Dose: 1 gram 3 times/day for 7 days.
  • Famciclovir 500mg po TID for 7 days
    • LU code 147 – Herpes zoster in patients 50 years of age or older, up to 72 hours* after appearance of lesions. Dose: 500mg 3 times/day for 7 days.)

Note that all these agents are renally eliminated. In individuals with renal impairment, dosage adjustment will be required.

Often when treatment is initiated within 72 hours of onset of symptoms, antiviral therapies can be quite effective. If presentation is more than 72 hours, a course of antiviral therapy is still recommended if the risk of painful complications is high. Ophthalmic herpes zoster often requires antiviral treatment, even beyond 72 h of onset, unless treatment is contraindicated.

A treatment duration of 7 days is the general recommendation for uncomplicated cases. However, there is no consensus about extending the duration of treatment for patients who still have new vesicles forming on the 7th day, or those with cuteneous, neurologic or ocular complications.

Acute Pain Management

Pain control is important to address the acute pain during the active phase as well as the post-herpetic neuralgia.  For acute mild to moderate pain, acetamionphen and NSAIDs are preferred. If pain is moderate to severe, opioids with morphine and oxycodone can be effective.  It may also be paramount to introduce gabapentin, pregabalin or tricyclic antidepressants or corticosteroids in cases where opioids have not been effective.

Corticosteroids can reduce pain of acute herpes zoster, accelerate lesion healing and help patients to resume to daily activities. The typical dose is oral prednisolone 1mg/kg/day for 7 days, followed by 0.5mg/kg/day for 7 days, then 0.25mg/kg/day for 7 days.  It is also recommended to refer to a pain specialist for sympathetic and epidural neural blockade if pain remains intractable with medications.

Treatment of Post-Herpetic Neuralgia (PHN)

The therapeutic ladder for treatment of post-herpetic neuralgia begins with first line options:

  1. Topicals such as topical lidocaine and topical capsaicin.
  2. If these are ineffective, then second line therapies are anticonvulsants such as gabapentin, pregabalin and tricyclic antidepressants (amitriptyline, nortriptyline and desipramine).
  3. If these are ineffective, then third line options are opioid analgesics such as tramadol, morphine, oxycodone and methadone.

What about prevention?

The zoster vaccine (Zostavax) is a one-dose, high potency, live-attenuated vaccine that boosts VZV-specific cell-mediated immunity. In one study by Oxman et al that was published in New England Journal of Medicine in 2006, the vaccine has demonstrated an efficacy of reducing the burden of illness if herpes zoster by 61.1%, the incidence of post-herpetic neuralgia by 66.5% and the incidence of herpes zoster by 51.3%.  However, this study enrolled about 38546 patients mostly aged 60 years of age or older.

In Sept 2016, Public Health Ontario has decided to publicly fund the zoster vaccine for individuals between the age of 65 and 70 years of age. For more information, please click here.

Normally, a single dose of zoster vaccine costs about $200 per injection.

Here are some of my thoughts around the management of Shingles:

  • If shingle is diagnosed early enough (e.g. within 72 hrs of symptoms onset), treatment with antiviral is quite effective. Health care providers should be educated and familiar with the typical clinical manifestation of shingles in older individual so that treatments are started promptly to prevent or minimize complications with post-herpetic neuralgia.
  • While acyclovir is covered by ODB as a general benefit, valacyclovir and famciclovir are covered as limited use criteria.  If clinicians decide to treat with either of these agents, please make every effort to ensure the LU codes are listed. Many times, prescriptions are turned away or delayed due to missing the LU codes. Pharmacists should also exercise professional judgement in these situations. It is best not to delay treatment for Shingles.
  • In individuals with renal impairment, please verify how dosage adjustment may be required for the antiviral therapy.
  • The topic always come up as to whether immunocompromised individuals can receive the zoster vaccine. Given zoster vaccine is made with live attenuated virus, there is definitely some concerns around its safety in immunocompromised host. Based on expert opinion, the Canadian Rheumatology Association recommends that patients, who are ≥60 years of age with rheumatoid arthritis and who are on methotrexate ≤25 mg/week and/or prednisone <20 mg/day, may receive Zostavax®.
  • For the management of postherpetic neuralgia, I wish the Ontario Drug Benefits would consider listing topical capsaicin and topical lidocaine. After all, these are considered first line options and should be offered first, instead of exposing individuals to systemic options which have serious side effects.
  • Zoster vaccine is an option to consider. However, Public Health Ontario is only funding the vaccine for individuals between the age of 65-70. For others who cannot afford the vaccine or that it is contraindicated, treatment of herpes zoster is still the most practical option.

Thank you for reading my post and I would love to hear your experience with treatment or prevention of Shingles in your practice.

 

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