Fast onset of relief after topical phenytoin in neuropathic pain after chemotherapy

Abstract

During or after chemotherapy, a peripheral neuropathy might rise. Neuropathic pain in such cases is often difficult to treat, and pain is sometimes even increasing in intensity after the cessation of chemotherapy. In 2016 we started a topical phenytoin project to treat pain due to chemotherapy induced peripheral neuropathy (CIPN) and meanwhile we monitored the efficacy and safety of a special phenytoin 5% or 10% cream in great detail in 6 patients suffering from CIPN. We will present in some detail one exemplary case from this cohort, responding to application of the cream. In all 6 cases a fast onset of perceptible pain relief was reported by patients. This is of great importance, as a fast onset will support compliance and help patients to rapidly perceive perspective in their chronic burden.

Efficacy of a topical gabapentin gel in a cisplatin paradigm of chemotherapy-induced peripheral neuropathy

“…A variety of topical preparations have been investigated in CIPN. These include a baclofen with amitriptyline plus ketamine organogel (BAK) combination [37], low-concentration menthol [38, 39], phenytoin [40], an amitriptyline and ketamine cream [41] and topical combinations of α 2 -adrenergic receptor agonists or nitric oxide (NO) donors combined with either phosphodiesterase (PDE) or phosphatidic acid (PA) inhibitors [42].…”

Pain in chemotherapy-induced peripheral neuropathy: NGF and the logic of topical phenytoin cream

“…Recently we demonstrated that it can be of use to apply topical formulations containing phenytoin, a broad acting sodium channel blocker, in pain due to CIPN. Phenytoin application resulted in a fast onset of action; within a time frame of 30 minutes, patients report clinical relevant reductions of pain [5][6][7]. This quick onset of action suggests indeed a local effect on the structures in the epidermis, such as the keratinocytes and the nociceptors (Figure 1).…”

“…In the past we reported a number of patients suffering from burning pain in both feet due to CINP, pain which did not subside after months or years following the chemotherapy. Topical treatment with phenytoin 10% diminished the pain considerably, and increased quality of life [5][6][7]. It might be that an ex juvantibus approach using topical phenytoin,could result in relevant pain reduction in a subcohort of CIPN patients, in case of a close fit between phenytoin's mechanism of action and the pathophysiology of CIPN pain.…”