Pharmacotherapy Newsletter

Volume 1, Issue 45, 11/23/2009

Question

How does the capsaicin 8% patch (Qutenza) work differently from traditional topical capsaicin cream/ointment used in the treatment of chronic pain?

Answer

On November 16, 2009, the Food and Drug Administration (FDA) approved capsaicin 8% patch (Qutenzaâ) by prescription for the management of neuropathic pain associated with postherpetic neuralgia (PHN).(1)  As a result, Pharmacology Weekly has decided to send this out as a Pharmacotherapy Newsletter issue that is serving as an update to previously published newsletters that described the mechanism of action for over-the-counter (OTC) capsaicin cream/ointment use in chronic pain management.(2,3)  Furthermore, this issue will also provide updated information related to the exact receptor being stimulated on the nerve endings of the unmyelinated afferent C-fiber neurons that are involved in the transmission of chronic pain.  This is relevant given that the mechanism of action had historically been thought to be primarily due to a depletion of substance P.  As described in the previous newsletter publications and reinforced here, depletion of substance P is not the primary mechanism for its ability to provide long-term pain control. 

Two of the primary problems with the use of traditional OTC capsaicin cream or ointment include the need for frequent reapplication of the medication and the burning discomfort associated with its application.  Topical use of the cream or ointment needs to be applied at least three to four times a day and on a scheduled basis.(4)  Patients will also have to endure...

The complete answer to this question comes with a diagram that explains the mechanism for this new dosage formulation.

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