Capsaicin

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DRUGS
Capsaicin

Capsaicin belongs to the class of topical analgesics. Capsaicin is a neuropeptide releasing agent selective for primary sensory peripheral neurons. Capsaicin aids in controlling peripheral nerve pain.

Introduction

Capsaicin belongs to the class of topical analgesics. Capsaicin is a neuropeptide releasing agent selective for primary sensory peripheral neurons. Capsaicin aids in controlling peripheral nerve pain.

Pharmacological class: Topical Analgesic

Indications

  • Postoperative pain

  • Diabetic neuropathy and postherpetic neuralgia

  • Cluster headaches

  • Osteoarthritis and rheumatoid arthritis

Pharamcological Action

Capsaicin works by first stimulating and then decreasing the intensity of pain signals in the body. Although pain may at first increase, it usually decreases after the first use. Capsaicin stimulates the release of a compound believed to be involved in communicating pain between the nerves in the spinal cord and other parts of the body.

Dosage

Usual Adult Dose for Postherpetic Neuralgia

Up to 4 patches can be applied and allowed to remain in place for 30 minutes for the feet and 60 minutes for other locations

Usual Adult Dose for Pain

Not to be applied more than 3 to 4 times a day

Pharmacokinetics

There has been no published data from low-concentration formulations, but after 60 or 90 min capsaicin 8% patch treatments for painful peripheral neuropathy, plasma concentrations are also very low (with a population Cmax of 1.86 ng ml−1) and transient (mean elimination half-life of 1.64 h). The longer elimination half-life of topical capsaicin relative to oral exposure is likely to reflect its slow release from the skin at the patch application site.

Contraindications

  • Contraindicated in patients with hypersensitivity to capsaicin

  • Contraindicated in pregnancy

  • Contraindicated in children younger than 18-year-old

Drug Interactions

  • If a patient is being administered treatment of generic drugs for varied multiple conditions, then capsaicin should not be used without the supervision of a physician.

  • Capsaicin should not be consumed by individuals on ACE inhibitors, agents that reduce stomach acid, aspirin, blood-thinning medications and herbs, and theophylline

Side effects

Common (affecting between 1 in10 to 1 in 100)

  • Burning

  • Itching

  • Dryness

  • Pain

  • Redness

  • Swelling, or soreness at application site

Uncommon (affecting 1 in 100 to 1 in 1000)

  • Blurred vision

  • Dizziness

  • Headache

  • Nervousness

  • Pounding in the ears

  • Slow or fast heartbeat

Very rare (affecting less than 1 in 10,000)

  • Bloating or swelling of the face, arms, hands, lower legs, or feet

  • Increased sensitivity to pain

  • Increased sensitivity to touch

  • Rapid weight gain

  • Tingling in the hands and feet

  • Unsteadiness or awkwardness

  • Unusual weight gain or loss

  • Weakness in the arms, hands, legs, or feet

Precautions

  • Always wear gloves when applying ointment to affected area

  • Apply when skin is cool. Do not apply after bathing or using heating pad

  • Do not get ointment in the eyes or nose.

  • Do not apply to broken skin

  • Pregnant women should consult their physician before use

  • Do not wrap the affected area with cloth or heating pad.

Clinic Evidence

In a randomized double-blind multi-centre study, 281 patients suffering from chronic soft tissue pain were treated either with a cream containing capsaicin 0.05% (n = 140) or placebo (n = 141). Of these, 151 were excluded from the ITT analysis, as they had in addition to their soft-tissue pain, pain of other origin. The primary outcome measure was a positive treatment response, defined as a pain sum score reduction of 30% or more. After 3 weeks of treatment, median pain sum score had decreased by 49% (capsicum group) and 23% (placebo group) (ITT analysis, p = 0.0006). The odds ratio of the responders in favor for capsaicin was 4.3 (CI 97.5% lower limit 1.9, p < 0.0001). Improvements in secondary efficacy measures confirmed the results. Likewise, all outcome measures had significantly more improved in the capsaicin compared with the placebo chronic back pain sufferers. All patients were included in the safety assessments. More adverse events occurred in the capsicum group (n = 13) than in the placebo group (n = 6). The capsaicin cream was generally well tolerated. The results indicate that capsaicin cream is useful in patients with chronic soft tissue pain and is also efficacious in patients with chronic back pain for which effectiveness has been demonstrated in earlier clinical trials.1

References

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