“It has been suggested that the skin as a whole may act as a polymodal nociceptor which undergoes functional changes in painful conditions.” 
In neurogenic inflammation, the population of keratinocytes in the skin are characterized by upregulated sodium channels.  Phenytoin cream can inhibit sodium channels, not only in nerves, but also on keratinocytes:
Keratinocytes in normal skin: a balanced state without peripheral upregulation
In neurogenic inflammation, sodium channnels are upregulated on keratinocytes:
In neuropathic pain also the keratinocytes are participating in the peripheral winding-up
After application of phenytoin cream, pain is decreased, due to amongst others, normalization of the output of the keratinocytes, as the sodium channels are blocked , leading to clinical relevant pain reduction:
Phenytoin cream restores the balance and blocks overactive keratinocytes
Keratinocytes have been identified as key players in the peripheral upregulation of pain. By topical treatment using sodium channel blockers, such as phenytoin, pain can be reduced. In our hands pain reduction in neuropathic pain states characterized by neurogenic inflammatory factors (SFN, diabetic neuropathy, CIAP, herpes zoster, chemo-induced PNP  ), pain can be reduced within 20-30 minutes.
Phenytoin cream has been developed in 2 concentrations: 5 % and 10%. Phenytoin is an 80-years old molecule, but again and again with new applications in medicine. We have as first research group world wide identified phenytoin cream as a potent analgesic cream.
January 2017, Jan M. Keppel Hesselink, MD, PhD
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