Its clinical use has been limited by its narrow therapeutic index and high inter- and intra-individual pharmacokinetic variability.

[1] CYP2D6 accounts for only a small percentage of total hepatic CYP450s but it is one of the main pathways for phase one metabolism of xenobiotics.

[4] Most PMs have an autosomal recessive polymorphism in the CYP2D6 locus which results in the severely compromised metabolism of at least 25 drugs.

[9][10] The symptoms of peripheral neuropathy include weakness or sensory loss and pain in the arms, hand, legs, and feet.

Histological investigations indicate the development of phospholipoidosis, with scaly inclusions in hepatocytes, Schwann cells and other tissues which could point to the cause of peripheral neuropathy.