Medication Summary
Treatment of brachioradial pruritus remains a challenge. Most patients find relief with the application of cold packs that numb the skin; hence, a positive "ice-pack sign" is almost pathognomonic for this condition. [3] Oral antihistamines and topical corticosteroids are only occasionally of value. If potent or superpotent topical corticosteroids are used, care must be taken to avoid cutaneous atrophy from overzealous use. Occasionally, patients are helped with topical anesthetics (eg, lidocaine cream or gel) or with 5% topical doxepin.
Substance P is a neurotransmitter important in the transmission of pain and itch neural signals. Topical capsaicin cream (0.025-0.05%) is a natural plant product that depletes substance P from cutaneous nerve endings. [47] It has been reported by a number of authors to provide relief of brachioradial pruritus within weeks. [16, 22, 48, 49, 50] Capsaicin patches have also been used. [51, 52]
Numerous oral medications have been tried with varying success. Case reports describe sustained symptomatic relief with gabapentin (1800 mg/d), [33] lamotrigine (200 mg/d), [9] amitriptyline (25-150 mg qhs), [22] and pimozide (1-2 mg/d). Oxcarbemazepine has proven effective in several patients reported by Savk and Savk. [31] Risperidone has been used with some success in certain patients. No medication works predictably. When using psychotropic medications, obtaining a psychiatric opinion is advisable unless the treating physician commonly prescribes these agents.
Analgesic, Topical
Capsaicin topical (Zostrix High Potency, Trixaicin HP, Zostrix Sports)
Capsaicin is a natural chemical derived from plants of the Solanaceae family. It penetrates deep for temporary relief of minor aches and pains of muscles and joints associated with inflammatory reactions. Capsaicin may render skin and joints insensitive to pain by depleting substance P in peripheral sensory neurons. It has demonstrated effectiveness in several studies of diabetic neuropathic pain and in other types of neuropathic pain.
Antianxiety Agent
Doxepin cream (Prudoxin, Zonalon)
Doxepin is a TCA that has potent H1-blocking activity, making it quite useful for urticaria. However, it has very potent sedative and anticholinergic effects. It can be quite effective if used at bedtime because the sedative effects can help a patient with pruritus sleep. Widespread use produces sedation, as does use in areas of high percutaneous absorption (eg, genitals). Many individuals develop an allergy to topical doxepin.
Antiarrhythmic Agent, Class I-b
Lidocaine (Topicaine, Senatec)
Lidocaine decreases permeability to sodium ions in neuronal membranes. This results in the inhibition of depolarization, blocking the transmission of nerve impulses
Anticonvulsant
Gabapentin (Gabarone, Neurontin)
Gabapentin is a membrane stabilizer, a structural analogue of the inhibitory neurotransmitter GABA, which paradoxically is thought not to exert effect on GABA receptors. It appears to exert action via the alpha(2)delta1 and alpha(2)delta2 auxiliary subunits of voltage-gaited calcium channels. Gabapentin is used to manage pain and provide sedation in neuropathic pain.
Pregabalin (Lyrica)
Pregabalin is a structural derivative of GABA. Its mechanism of action is unknown. Pregabalin binds with high affinity to alpha2-delta site (a calcium channel subunit). In vitro, it reduces calcium-dependent release of several neurotransmitters, possibly by modulating calcium channel function. This agent is FDA approved for neuropathic pain associated with diabetic peripheral neuropathy, postherpetic neuralgia, or fibromyalgia. It is also indicated as adjunctive therapy in partial-onset seizures.
Antidepressant, Tricyclic
Amitriptyline (Elavil)
Amitriptyline is an analgesic for certain chronic and neuropathic pain. It blocks the reuptake of norepinephrine and serotonin, which increases concentration in the CNS. It decreases pain by inhibiting spinal neurons involved in pain perception. Amitriptyline is highly anticholinergic. It is often discontinued because of somnolence and dry mouth.
Cardiac arrhythmia, especially in overdose, has been described; monitoring QTc interval after reaching target level is advised. Up to 1 month may be needed to obtain clinical effects.
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Area of pruritus demarcated in pen in a middle-aged woman with brachioradial pruritus. Macroscopically, no skin changes are visible.
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Subtle excoriations on the dorsal forearm of a middle-aged woman with brachioradial pruritus.
