Pharmacology for Dentistry

Antiepileptic Agents 109

Clonazepam is well absorbed orally and
approximately 85 percent is bound with
plasma proteins, completely metabolized in
liver and excreted through kidney.

Adverse effects include sedation, lack
of concentration, irritability, ataxia and
behavioural abnormalities.

The detailed pharmacology of diazepam is
discussed in chapter ‘Sedative and hypnotics’.

CLOBAZAM

It is 1, 5 benzodiazepine with a chemical
structure slightly different from that of diaz-
epam and clonazepam. This change in struc-
ture results in less sedative and psychomo-
tor retardation. Though introduced as an
anxiolytic it has been found to be useful in
treatment of patients with refractory epilepsy.

Its antiepileptic activity results from its
binding to one or more specific GABA recep-
tors increasing GABA mediated inhibition.

Adverse reactions include drowsiness,
hangover effects, dizziness, weight gain,
headache, dry mouth and orthostatic
hypotension etc.

PHENYLTRIAZINE DERIVATIVE

LAMOTRIGINE

It is phenyltriazine compound, chemi-
cally unrelated to existing antiepileptic
drugs. It acts primarily via a dose depen-
dent blockade of voltage sensitive sodium
channels in their slow inactivated state,
thus stabilizing the presynaptic neuronal
membrane inhibiting release of excitatory
neurotransmitters mainly glutamate.

Lamotrigine is almost completely

absorbed after oral administration and

metabolized completely in liver.

The adverse effects include headache, rash,

nausea, dizziness, somnolence and insomnia.

It is mainly used as adjunctive therapy

in patients for simple partial seizures,

complex partial seizures, secondary

generalised tonic and clonic seizures.

NEWER COMPOUNDS

TOPIRAMATE

It is used as adjunctive treatment of

seizures including refractory seizures,

simple and complex partial seizures.

It acts by reducing epileptiform

discharges generated by blocking the

sensitive sodium channel and enhancing

the activity of GABA receptors.

It is rapidly absorbed after oral

administration and is unaffected by

presence of food and excreted mainly

through kidney.

Adverse effects include abdominal pain,

anorexia, weight loss, impaired concentra-

tion, confusion, mood disorders, ataxia, diz-

ziness, drowsiness, fatigue and psychotic

symptoms.

GABAPENTIN

It is a new anticonvulsant drug and is a

structural analogue of GABA. It increases

the release of GABA by unknown mecha-

nism. It modifies maximal electroshock as

well as inhibits pentylenetetrazol induced

convulsions.