Q: Which statement is true? - Select one
A) Fosphenytoin is the water-soluble prodrug of phenytoin
B) Fosphenytoin is the lipid-soluble prodrug of phenytoin
Answer: A
Fosphenytoin is a water-soluble prodrug that converts into phenytoin. It was created in the hope that it would act faster. It can also be given intramuscularly, which is an advantage when an IV line is not available. It can also be given three times faster, an advantage in status epilepticus scenarios.
Phenytoin carries various risks such as local irritation, tissue necrosis, and "purple glove syndrome", and if given faster, can cause cardiac arrhythmias. Fosphenytoin may negate those risks due to its water solubility.
#pharmacology
#neurology
References:
1. Madhiyazhagan M, Roshan R, Dhanapal SG, Joseph JV, Ganesan P, Mathew V, A Kundavaram PP. Comparison of Phenytoin and Fosphenytoin in Treatment of Active Seizures in the Emergency Department. Neurol India. 2023 May-Jun;71(3):447-452. doi: 10.4103/0028-3886.378665. PMID: 37322738.
2. Aaronson PM, Belgado BS, Spillane JP, Kunisaki TA. Evaluation of intramuscular fosphenytoin vs intravenous phenytoin loading in the ED. Am J Emerg Med. 2011 Nov;29(9):983-8. doi: 10.1016/j.ajem.2010.05.005. Epub 2010 Aug 3. PMID: 20685063.
3. DeToledo JC, Ramsay RE. Fosphenytoin and phenytoin in patients with status epilepticus: improved tolerability versus increased costs. Drug Saf. 2000 Jun;22(6):459-66. doi: 10.2165/00002018-200022060-00004. PMID: 10877039.