Pregabalin (Lyrica - Pfizer) is the first drug approved by the FDA for management of fibromyalgia. When it was first marketed, pregabalin, which is structurally similar to gabapentin (Neurontin, and others), was approved for treatment of neuropathic pain associated with postherpetic neuralgia and diabetic peripheral neuropathy and for adjunctive treatment of partial onset seizures in adults with epilepsy. It has also been prescribed off-label for other types of neuropathic pain such as sciatica.

Pregabalin (Lyrica - Pfizer), a structural analog of gamma-aminobutyric acid (GABA) similar to gabapentin (Neurontin - Pfizer, and others), which recently became available generically, has been approved by the FDA for treatment of neuropathic pain associated with postherpetic neuralgia (PHN) and diabetic peripheral neuropathy (DPN), and for adjunctive treatment of partial onset seizures in adults with epilepsy.

The FDA has required new warnings in the labels of gabapentin (Neurontin, and others) and pregabalin (Lyrica, Lyrica CR, and generics) about the risk of life-threatening or fatal respiratory depression in patients with respiratory risk factors. Respiratory risk factors include chronic obstructive pulmonary disease (COPD) and concurrent use of opioids or other CNS depressants. Elderly patients are also at increased risk.

A nephrologist and longtime reader of The Medical Letter wrote us to say that our recent article entitled Drugs for Anxiety Disorders should have said more about the need for dosage adjustment of gabapentin (Neurontin, and others) and pregabalin (Lyrica, and others) in patients with renal impairment. Both drugs, he pointed out, are exclusively renally eliminated and can accumulate in patients with diminished renal function. Symptoms, which can include altered mental status, may develop so slowly that neither the patient nor the practitioner connect them to the drug. The resolution of...

Duloxetine (Cymbalta - Lilly) is the second drug to be approved by the FDA for treatment of fibromyalgia. Pregabalin (Lyrica), which is also approved for treatment of neuropathic pain and epilepsy, was the first. Duloxetine is a selective serotonin and norepinephrine reuptake inhibitor (SNRI) that is already marketed for treatment of depression and diabetic neuropathy.

A lidocaine 1.8% patch (ZTlido – Scilex) has been approved by the FDA for treatment of pain associated with postherpetic neuralgia (PHN). A lidocaine 5% patch (Lidoderm, and generics) was approved earlier for the same indication and has been used off-label for treatment of other types of localized pain. Both of these patches are available only by prescription. Lidocaine 4% patches (Aspercreme, IcyHot, and others) are available over the counter for back, neck, shoulder, and joint pain.

The FDA has approved a topical 8% patch formulation of capsaicin (Qutenza – NeurogesX), available only by prescription, for local treatment of postherpetic neuralgia. Postherpetic neuralgia occurs after herpes zoster in about one third of patients ≥60 years old and can persist for months or even years.

Difelikefalin (Korsuva – Vifor), an IV kappa opioid receptor (KOR) agonist, has been approved by the FDA for treatment of moderate to severe pruritus associated with chronic kidney disease (CKD) in adults on hemodialysis. It is the first drug to be approved for this indication and the first KOR agonist to become available in the US. Difelikefalin has not been studied in patients on peritoneal dialysis.

Interim results of a double-blind, placebo-controlled trial suggest that off-label use of the anticholinergic drug oxybutynin may reduce the frequency and severity of hot flashes in women with breast cancer. Extended-release oral oxybutynin (Ditropan XL, and generics) has been shown to reduce the frequency and severity of hot flashes in healthy menopausal women.

Milnacipran (Savella - Forest), an oral selective serotonin and norepinephrine reuptake inhibitor (SNRI), is the third drug approved by the FDA for management of fibromyalgia. The 2 others are pregabalin, a gammaaminobutyric acid (GABA) analog also approved for treatment of diabetic neuropathy, post-herpetic neuralgia and epilepsy, and duloxetine, an SNRI also approved for treatment of depression, diabetic neuropathy and generalized anxiety disorder.