What is the treatment for postherpetic neuralgia (PHN)?

From the Guidelines

Post-herpetic neuralgia should be treated with a multi-modal approach, starting with anticonvulsants like gabapentin (300-1200 mg three times daily) or pregabalin (75-300 mg twice daily), which are first-line options, as recommended by the 2017 HIVMA of IDSA clinical practice guideline for the management of chronic pain in patients living with HIV 1.

Treatment Options

• Anticonvulsants: gabapentin (300-1200 mg three times daily) or pregabalin (75-300 mg twice daily) are first-line options for treating post-herpetic neuralgia, with a number needed to treat (NNT) of 4.39 for gabapentin and 4.93 for pregabalin 1.
• Tricyclic antidepressants: such as amitriptyline (10-75 mg at bedtime) are also effective, with an NNT of 2.64 1.
• Topical relief: lidocaine 5% patches applied to the painful area for 12 hours daily or capsaicin 8% patches applied by a healthcare provider can help, with an NNT of 2 for lidocaine patches and 3.26 for capsaicin 0.075% 1.

Treatment Considerations

• Patients should start medications at low doses and increase gradually to minimize side effects.
• Treatment typically continues for 2-6 months, with gradual dose reduction as pain improves.
• Early treatment of shingles with antivirals like acyclovir, valacyclovir, or famciclovir within 72 hours of rash onset can reduce the risk of developing post-herpetic neuralgia, especially in older adults who are at higher risk.
• In severe cases, opioid analgesics may be considered short-term, but their long-term use should be avoided due to addiction risks, with an NNT of 2.67 for certain opioids like oxycodone, extended-release morphine, and methadone 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.

Postherpetic Neuralgia Treatment: Gabapentin is effective in the management of postherpetic neuralgia (PHN).

• The medication demonstrated efficacy in two randomized, double-blind, placebo-controlled studies.
• Patients experienced a reduction in weekly mean pain scores as early as Week 1, which was maintained throughout the treatment period.
• The studies support the use of gabapentin for the management of PHN, with dosages of 1800 and 2400 mg/day showing efficacy 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

Alternative Treatment Option: Pregabalin is also an effective treatment for postherpetic neuralgia.

• Three double-blind, placebo-controlled studies demonstrated the efficacy of pregabalin in managing PHN.
• Patients experienced a significant improvement in mean pain scores and a reduction in pain intensity from baseline.
• The studies support the use of pregabalin for the management of PHN, with dosages of 75,150, and 300 mg twice daily showing efficacy 3.

From the Research

Definition and Symptoms of Postherpetic Neuralgia

• Postherpetic neuralgia is a persistent pain condition often characterized by allodynia and hyperalgesia, resulting from an acute herpes zoster vesicular eruption that has healed 4.
• The pain associated with postherpetic neuralgia can severely affect a patient's quality of life, quality of sleep, and ability to participate in activities of daily living 4.

Treatment Options for Postherpetic Neuralgia

• First-line treatments for postherpetic neuralgia include the administration of medication therapies such as tricyclic antidepressants, pregabalin, gabapentin, and lidocaine patches 4, 5.
• Second- or third-line therapies include the application of tramadol and capsaicin creams and patches 4, 5.
• Interventional therapies, such as transcutaneous electrical nerve stimulation, local botulinum toxin A, cobalamin, and triamcinolone injection, are valuable for patients who do not respond to conservative options 4, 6.
• Spinal cord stimulation and peripheral nerve stimulation are possibly useful for the treatment of postherpetic neuralgia, although the evidence is not strong enough to support a high level of recommendation 4, 6.

Recommended Interventional Treatments

• Subcutaneous injection of botulinum toxin A or triamcinolone, transcutaneous electrical nerve stimulation, peripheral nerve stimulation, and stellate ganglion block are recommended as first-line interventional treatments 4.
• Paravertebral block and pulsed radiofrequency are recommended as second-line interventional treatments 4.
• Spinal cord stimulation could be considered if severe pain persists 4, 6.

Starting Dose of Gabapentin for Postherpetic Neuralgia

• A starting dose of 600 mg/day gabapentin could be a safe and effective starting dose for patients with postherpetic neuralgia, with minimal side effects 7.

Management of Herpes Zoster and Postherpetic Neuralgia

• Antivirals should be started, preferably within 72 h of onset, to reduce the severity and duration of the eruptive phase and to reduce the intensity of acute pain 8.
• Early initiation of gabapentin or amitriptyline after the onset of herpes zoster is suggested for patients at high risk of developing postherpetic neuralgia 8.