Topical Capsaicin Cream Research Articles

Management of herpes zoster (shingles) and postherpetic neuralgia

Herpes zoster (HZ) results from recrudescence of varicella zoster virus latent since primary infection (varicella). The overall incidence of HZ is ∼ 3/1000 of the population per year rising to 10/1000 per year by 80 years of age. Approximately 50% of individuals reaching 90 years of age will have had HZ. In ∼ 6%, a second attack may occur (usually several decades after the first). Patients with HZ can transmit the virus to a non-immune individual causing varicella. HZ is not contracted from individuals with varicella or HZ. Reduced cell-mediated immunity to HZ occurs with ageing, explaining the increased incidence in the elderly and from other causes such as tumours, HIV and immunosuppressant drugs. Diagnosis is usually clinical from typical unilateral dermatomal pain and rash. Prodromal symptoms, pain, itching and malaise, are common. The most common complication of HZ is postherpetic neuralgia (PHN), defined as significant pain or dysaesthesia present ≥ 3 months after HZ. PHN results from damage and secondary changes within components of the nervous system subserving pain. Some motor deficit is common; severe and long-lasting paresis may rarely accompany HZ. More than 5% of elderly patients have PHN at 1 year after acute HZ. Predictors of PHN are, greater age, acute pain and rash severity, prodromal pain, the presence of virus in peripheral blood as well as adverse psychosocial factors. Therapy for acute HZ is intended to reduce acute pain, hasten rash healing and reduce the risk of PHN and other complications. Antiviral drugs are close to achieving these aims but do not entirely remove risk of PHN. Oral steroids show no protective effect against PHN. Adequate analgesia during the acute phase may require strong opioid drugs. Nerve blocks and tricyclic antidepressants (TCAs) may reduce the risk of PHN although firm evidence is lacking. PHN requires thorough evaluation and development of a management strategy for each individual patient. Initial therapy is with TCAs (e.g., nortriptyline) or the anticonvulsant gabapentin. Topical lidocaine patches frequently reduce allodynia. Strong opioids are sometimes required. Topical capsaicin cream is beneficial for a small proportion of patients but is poorly tolerated. NMDA antagonists have not proved beneficial with the exception of ketamine. Transcutaneous Electrical Nerve Stimulation (TENS) may be effective in some cases. HZ is a common condition. Severe complications such as stroke, encephalitis and myelitis are relatively rare whereas sight threatening complications of ophthalmic HZ are more common. PHN is common, distressing and often intractable. Good management improves outcome.

Role of intra-articular hyaluronic acid preparations in medical management of osteoarthritis of the knee

Objective: This article reviews the various pharmacological modalities for the treatment of osteoarthritis (OA) of the knee, with a particular emphasis on the use of intra-articular (IA) hyaluronic acid (HA). Methods: A literature review of the pharmacotherapy of OA of the knee was performed. Reviewed studies included those involving acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), topical analgesics, IA corticosteroids, and IA HA. Results: According to American College of Rheumatology (ACR) guidelines, acetaminophen should be used as first-line oral therapy. NSAIDs can be tried if nonpharmacological therapy and acetaminophen fail to provide adequate symptom relief. Topical capsaicin cream, either as monotherapy or as adjunctive therapy, is recommended for patients who do not respond to analgesics or who do not wish to take systemic therapy. IA corticosteroids are recommended for patients who have an effusion and local signs of inflammation. IA HA preparations are indicated for the treatment of pain in patients with OA of the knee who have failed to respond adequately to conservative nonpharmacologic therapy and to simple analgesics. Clinical trials show that IA HA therapy results in improvement in knee pain and function that is superior to placebo and comparable to NSAIDs. Conclusions: Treatment with IA HA products appears to offer a significant advantage over aspiration and placebo injections for up to 6 months. It also may have an advantage over IA glucocorticoids. Semin Arthritis Rheum 30:2-10. Copyright © 2000 by W.B. Saunders Company

Diabetic Neuropathies.

There are currently no treatments available (beyond optimal control of hyperglycemia) that arrest or reverse progressive diabetic polyneuropathy. Consultation with a diabetologist is indicated for patients with poorly controlled disease and polyneuropathy. Immunotherapy for diabetic lumbosacral plexopathy has been advocated but is not supported to date by class 1 clinical trial evidence. Pharmacologic treatment for painful neuropathy may include topical anesthetics, capsaicin cream, anticonvulsants, tricyclic antidepressants, mexiletine, and opioids. Gabapentin, a newer anticonvulsant, has an attractive side-effect profile (a consideration in older patients) and has fewer interactions with other drugs. Amitriptyline may cause excessive sedation, postural hypotension, constipation, and urinary retention, but low evening doses (10 to 25 mg), slowly titrated upward, may offer relief from nocturnal pain. Opioids should not be withheld from patients with severe pain or with intolerance of or contraindications to other agents. A single physician should supervise their use.

Topical capsaicin as an adjuvant analgesic for the treatment of traumatic amputee neurogenic residual limb pain

The treatment of amputee residual limb pain can at times be a challenge for the physician. Occasionally, traditional analgesic medication regimens cannot be used or are ineffective in relieving the pain. Topical capsaicin cream has been a beneficial adjuvant medication in the treatment of some painful conditions. The authors present three patients with traumatic upper limb amputations where topical capsaicin cream was of benefit in the treatment of neurogenic residual limb pain. The hope is that these cases will increase awareness of the potential use of capsaicin cream as an adjuvant analgesic in patients with residual limb pain. Common causes of residual limb pain and the pharmacology of capsaicin cream are discussed.

Treatment of aquagenic pruritus with topical capsaicin cream

Aquagenic pruritus is characterized by pruritus after contact with water; there are no objective cutaneous changes. Capsaicin, which induces the release of neuropeptides from A delta and C cutaneous nerve fibers, has been successfully used in the treatment of several dermatoses associated with pruritus. Among the many different neuropeptides present in human skin, the undecapeptide substance P has been shown to cause pruritus. We evaluated the clinical effect and searched for alterations in cutaneous neuropeptidergic fibers before and after treatment with capsaicin cream. Five patients with aquagenic pruritus were treated with capsaicin cream 0.025%, 0.5% or 1.0% three times daily for 4 weeks. Direct immunofluorescence (DIF) was performed before and after treatment to evaluate the storage of neuropeptides in the A delta and C type cutaneous nerve fibers. Before treatment (when by DIF the neuropeptidergic fibers appeared filled with neuropeptides), contact with water consistently provoked itching. After capsaicin treatment (when by DIF the neuropeptidergic fibers were depleted of neuropeptides), contact with water did not evoke pruritus. Areas of skin treated with the vehicle alone showed no clinical improvement or change in neuropeptide content. This study suggests that neuropeptides, including substance P, may contribute to mediating the itch in aquagenic pruritus.