Topical analgesia is a viable option

The last 2 decades more and more attention has been given to topical analgesia. Peripheral nerves in the epidermis are influenced by topical analgesics with the aim to reduce neuropathic pain. Systemic side effects are rare, because the purpose of topical analgesics is not to penetrate deeper than the epidermis. Thus topical analgesics are particularly beneficial in the treatment of geriatric patients with high risk of undesirable side effects, drug interactions and altered metabolization due to intake of multiple medications. Even high concentrations of active compounds in topical analgesics do not give rise to serious side effects, such as ketamine cream up to 20% [1]. The absence of severe side effects most probably resides in the fact that the skin has its own metabolism for xenobiotic molecules [2]. Metabolism of ketamine occurs through various cytochrome P450s enzymes (CYP2B6, 2C9, 2C19, 3A4, 2A6, and 3A5), which are present in the epidermis [2].