primidone

Q: 22 years old male is brought to ER with acute symptoms of ataxia, nausea, vomiting, severe sedation, and dizziness. Primidone is recently added to patient's anti-seizure medicines. Primidone is a prodrug of? (select one)

 A) phenobarbital

B) phenytoin

C) clonazepam

D) gabapentin

E) valproate

Answer: A

In the body, Primidone gets converted into two active metabolites, named phenobarbital and phenylethylmalonamide (PEMA). Phenobarbital binds to the GABA(A) receptor. PEMA enhances the activity of phenobarbital. 

Although primidone is a prodrug of phenobarbital and as expected many side-effects are the same as of phenobarbital, primidone can produce acute adverse reactions independent of it consisting of dizziness, ataxia, nausea, and vomiting.

#toxicology

#pharmacology

#neurology

References:

1. Abou-Khalil BW. Antiepileptic Drugs. Continuum (Minneap Minn) 2016; 22:132.

2. Lenkapothula N, Cascella M. Primidone. 2021 Jul 29. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 32965968.