The new PHN drug is Qutenza. It's made by Lohmann Therapie-Systems AD of Andernach, Germany, and distributed by NeurogesX Inc. of San Mateo, Calif.
PHN is excruciating, and is often described as a burning, stabbing, or gnawing pain. It starts with an attack of shingles, in which the herpes zoster virus -- the chickenpox virus, lying dormant at nerve roots -- reactivates.
PHN is pain that persists after the shingles scales heal. It affects 10% to 15% of people who have shingles. It may get better over time. It may not. Treatments include prescription pain medications, anticonvulsants, and antidepressants.
Now there's Qutenza, a radically different approach. The active ingredient in Qutenza is synthetic capsaicin, the chemical that makes chili peppers burn. There are over-the-counter capsaicin products, but the FDA notes in a news release that "Qutenza is the first pure, concentrated, synthetic capasaicin-containing prescription drug to undergo FDA review."
"The product can provide effective pain relief for patients who suffer from PHN," Bob Rappaport, MD, FDA director of Anesthesia, Analgesia, and Rheumatology Products, said in a news release.
Qutenza is applied by a doctor via a patch or patches placed for an hour on the places on the skin that hurt. Before applying the patch, the doctor spreads a topical anesthetic on the area to be treated.
After an hour, the doctor carefully removes the patch. For a few days, the treated areas may be sensitive to heat from hot showers, sunlight, or vigorous exercise.
The drug burns during application. The drug's label warns that there may be "substantial procedural pain." In clinical trials, 42% of patients reported pain, and 63% reported reddening of the skin. But only 1% of patients discontinued treatment due to these or any other side effect.
Patients may receive an opioid pain drug before or after treatment.
Qutenza may cause a temporary increase in blood pressure that can last for two hours after treatment. Usually this blood pressure increase is less than 10 points, but some patients have had greater increases.
Does it work? Qutenza is not a cure for PHN. But in clinical trials, 40% to 50% of treated patients reported that their pain was at least 30% less severe.
Qutenza may be used in combination with other PHN treatments. Qutenza treatment may be repeated every three months.