Chemical Structure:
C15H12N2O2
Mechanism of Action:
Phenytoin works by inhibiting voltage-gated sodium channels, which decreases the release of glutamate, the body's main excitatory neurotransmitter.
Structure-Activity Relationship (SAR) of Phenytoin:
1.Hydantoin Ring:
Phenytoin's core structure is a hydantoin ring, which is essential for its antiepileptic activity. The hydantoin ring is a five-membered ring containing two nitrogen atoms.
2.Phenyl Group:
The presence of a phenyl group at position 5 of the hydantoin ring is crucial. This phenyl group significantly enhances the anticonvulsant activity of the molecule.
3.Substitution at Position 5:
The substitution pattern, particularly at the 5th position of the hydantoin ring with a phenyl group, is critical for activity. Modifications here can drastically affect the drug's efficacy and potency.
4.Lipophilicity:
The overall lipophilicity of the molecule, contributed by the phenyl group, affects its pharmacokinetic properties, including absorption and brain penetration, which are important for its antiepileptic effects.
Synthesis of Phenytoin (Chemical Reaction):
The synthesis of Phenytoin is typically done through the following simplified reaction:
1.Condensation of Benzil with Urea:
Benzil + Urea → (heat, base, or acid catalyst) → Phenytoin
In this reaction, benzil (a diketone) is condensed with urea under heat, typically in the presence of a base or acid catalyst. The reaction proceeds through the formation of an intermediate that cyclizes into the hydantoin ring, resulting in Phenytoin.
Uses:
It's used as an anticonvulsant to control seizures.
Side Effects:
It can cause dizziness, drowsiness, and, in more serious cases, liver damage.