What is the treatment for Postherpetic Neuralgia (PHN)?

From the Guidelines

Postherpetic neuralgia should be treated with gabapentin as a first-line oral pharmacological treatment, with a typical adult regimen titrating to 2400 mg per day in divided doses, as recommended by the 2017 HIVMA of IDSA clinical practice guideline for the management of chronic pain in patients living with HIV 1. The treatment of postherpetic neuralgia typically begins with topical agents like lidocaine 5% patches applied to the painful area for 12 hours daily or capsaicin 8% patches applied by healthcare providers.

• Oral medications are often needed, including:
  • Anticonvulsants (gabapentin 300-1200 mg three times daily or pregabalin 75-300 mg twice daily)
  • Tricyclic antidepressants (amitriptyline 10-75 mg at bedtime)
  • SNRIs (duloxetine 30-60 mg daily)
• For severe cases, opioids like tramadol or oxycodone may be considered short-term.
• Treatment should be individualized and may require combination therapy.
• Non-pharmacological approaches include TENS units, physical therapy, and psychological support.
• Prevention is important through zoster vaccination for adults over 50. The pain typically improves gradually over months, though some patients experience persistent symptoms requiring long-term management, as noted in the 2017 HIVMA of IDSA clinical practice guideline for the management of chronic pain in patients living with HIV 1. Early treatment of shingles with antivirals within 72 hours of rash onset can reduce the risk of developing postherpetic neuralgia, as supported by the 2017 HIVMA of IDSA clinical practice guideline for the management of chronic pain in patients living with HIV 1. If patients have an inadequate response to gabapentin, clinicians might consider a trial of pregabalin for patients with post-herpetic neuralgia, as recommended by the 2017 HIVMA of IDSA clinical practice guideline for the management of chronic pain in patients living with HIV 1. Capsaicin is recommended as a topical treatment for the management of chronic HIV-associated peripheral neuropathic pain, with a single 30-minute application of an 8% dermal patch or cream administered at the site of pain providing pain relief for at least 12 weeks, as noted in the 2017 HIVMA of IDSA clinical practice guideline for the management of chronic pain in patients living with HIV 1.

From the FDA Drug Label

Gabapentin was evaluated for the management of postherpetic neuralgia (PHN) in two randomized, double-blind, placebo-controlled, multicenter studies. The intent-to-treat (ITT) population consisted of a total of 563 patients with pain for more than 3 months after healing of the herpes zoster skin rash Both studies demonstrated efficacy compared to placebo at all doses tested The reduction in weekly mean pain scores was seen by Week 1 in both studies, and was maintained to the end of treatment.

Gabapentin is effective for the management of postherpetic neuralgia (PHN), with significant reduction in pain scores seen as early as Week 1 and maintained throughout treatment, as demonstrated in two randomized, double-blind, placebo-controlled studies 2.

The efficacy of pregabalin for the management of postherpetic neuralgia was established in three double-blind, placebo-controlled, multicenter studies These studies enrolled patients with neuralgia persisting for at least 3 months following healing of herpes zoster rash and a minimum baseline score of greater than or equal to 4 on an 11-point numerical pain rating scale Treatment with all doses of pregabalin statistically significantly improved the endpoint mean pain score and increased the proportion of patients with at least a 50% reduction in pain score from baseline

Pregabalin is also effective for the management of postherpetic neuralgia, with significant improvement in pain scores and a significant proportion of patients achieving at least a 50% reduction in pain score from baseline, as demonstrated in three double-blind, placebo-controlled studies 3.

• Key points:
  • Gabapentin and pregabalin are both effective for the management of postherpetic neuralgia.
  • Significant reduction in pain scores can be seen as early as Week 1 with gabapentin.
  • Pregabalin treatment results in significant improvement in pain scores and a significant proportion of patients achieving at least a 50% reduction in pain score from baseline.

From the Research

Definition and Characteristics of Neuralgia Postherpetica

• Neuralgia postherpetica, also known as post-herpetic neuralgia (PHN), is a chronic neuropathic pain condition that persists 3 months or more following an outbreak of shingles 4.
• PHN is associated with persistent and often refractory neuropathic pain, and patients may experience multiple types of pain, including constant deep, aching, or burning pain; paroxysmal, lancinating pain; hyperalgesia; and allodynia 4.

Treatment Options for Neuralgia Postherpetica

• The pharmacological treatment of PHN may include a variety of medications, such as alpha-2 delta ligands (gabapentin and pregabalin), other anticonvulsants (carbamazepine), tricyclic antidepressants (amitriptyline, nortriptyline, doxepin), topical analgesics (5% lidocaine patch, capsaicin), tramadol, or other opioids 4.
• First-line treatments for PHN include tricyclic antidepressants, gabapentin, and pregabalin, and the topical lidocaine 5% patch 5.
• Opioids, tramadol, capsaicin cream, and the capsaicin 8% patch are recommended as either second- or third-line therapies in different guidelines 5.
• Interventional therapies, such as transcutaneous electrical nerve stimulation, local botulinum toxin A, cobalamin, and triamcinolone injection, may be valuable for patients who do not respond to conservative options 6.

Comparison of Treatment Effectiveness

• A retrospective cohort study found that pregabalin (PGB) was more effective than gabapentin (GPT) in the treatment of PHN, with significantly higher clinical effectiveness and improved analgesic effect, sleep quality, and adverse emotions 7.
• The study also found that the overall incidence of adverse events was equivalent in the PGB and GPT groups 7.

Guidelines for Care

• Current guidelines on the care of patients with PHN recommend a stepped approach to treatment, with first-line treatments including tricyclic antidepressants, gabapentin, and pregabalin, and the topical lidocaine 5% patch 5.
• The guidelines also discuss the use of invasive procedures, such as sympathetic blockade, intrathecal steroids, and implantable spinal cord stimulators, for relief of PHN in patients refractory to noninvasive pharmacologic interventions 5.