Steroid myopathy

Q: Concomitant use of which of the following medications decrease the intensity of dexamethasone induced myopathy?

A) Neuro-muscular blockers
B) Phenytoin
C) Erythromycin
D) Proton Pump Inhibitors 
E) Propofol


Answer: B

Patients with brain tumor usually use dexamethasone and phenytoin concomitantly to reduce vasogenic edema and risk of seizures respectively and get the unintended benefit of interaction between steroid and phenytoin. This interaction is due to the induction of hepatic metabolism of dexamethasone by phenytoin. On the reverse side, phenytoin level needs to be monitored as it may have an exaggerated effect.


Reference:

Pharm.D. Lisa A.Lawson, Pharm.D. Robert A.Blouin, Ph.D.Randal B.Smith Pharm.D. Robert P.Rapp, M.D. A. ByronYoung - Phenytoin-dexamethasone interaction: A previously unreported observation - Surgical Neurology Volume 16, Issue 1, July 1981, Pages 23-24