Epilepsy gabapentin

Gabapentin and pregabalin are prescribed in certain epileptic diseases such as absence epilepsy and in neuropathic pain. Their therapeutic target for pain suppression is the a2S-l subunit. 

Figure 16.7 The structure of some established antiepileptic drugs (AEDs) and some newer ones. Note that while the structures of phenytoin and ethosuximide are similar and also close to that of phenobarbitone, they are effective in different forms of epilepsy. Vigabatrin, progabide and gabapentin are clearly related to GABA. Muscimol is a GABAa agonist but is not an effective antiepileptic drug...

Gabapentin inhibits high-voltage activated Ca channels and elevates human brain GABA levels. It is a second-line agent for patients with partial seizures who have failed initial treatment. It may also have a role in patients with less severe seizure disorders, such as new-onset partial epilepsy, especially in elderly patients. 

Ben-Menachem, E., Soderfelt, B., Hamberger, A., Hedner, T., and Persson, L. I. (1995) Seizure frequency and CSF parameters in a double-blind placebo controlled trial of gabapentin in patients with intractable complex partial seizures. Epilepsy Res. 21,231-236. 

In addition to treating insomnia, gabapentin has been used to treat epilepsy, anxiety disorders, and bipolar disorder. It is generally well tolerated with sedation and headaches being the only prominent side effects. Because gabapentin is excreted unchanged in urine, it does not require metabolism by the liver. It is therefore easily eliminated by elderly patients and those with liver disease, although it should be used with caution in those with poor renal (kidney) function. 

Neuropsychiatric adverse events (3 to 12 years of age) Gabapentin use in pediatric patients with epilepsy 3 to 12 years of age is associated with the occurrence of CNS-related adverse events. 

Marson AG, Kadir ZA, Hutton JL, Chadwick DW. Gabapentin add-on for drug-resistant partial epilepsy. Cochrane Database Syst Rev 1999. 

Rowan AJ, Ramsay RE, Collins JF, et. al. New onset geriatric epilepsy a randomized study of gabapentin, lamotrigine, and carbamazepine. Neurology 2005 64 1868-1873. 

Dimond, K.R., Pande, A.C., Lamoreaux, L., and Pierce, M.W. (1996) Effect of gabapentin (Neurontin) [corrected] on mood and wellbeing in patients with epilepsy. Progress in Neuropsychophar-macol Biol Psychiatry 20 407-17. [published erratum appears in Prog Neuropsychopharmacol Biol Psychiatry 1996 20(6) 1081]. 

Gabapentin has been approved in the United States since 1993 for adjunctive use in the management of treatment-refractory partial epilepsy. Early evidence in open-label trials indicated possible mood-stabilizing properties ( 227, 234). Recent data from a placebo-controlled crossover trial, however, found no difference between gabapentin and placebo for manic or depressed episodes (235). 

A compound commonly used for treating epilepsy but also has applications in treating pain (e.g. phenytoin, carbamezapine, gabapentin and sodium valproate). 

The patient is on gabapentin but this is for neuropathic pain rather than epilepsy so fluoroquinolones may be used. He may have renal or hepatic impairment. 

A 35-year-old woman with epilepsy without a history of psychiatric disorders developed elevated mood after being stabilized on gabapentin monotherapy (3200 mg/ day). After 5 months she developed a manic episode, which remitted when gabapentin was withdrawn. 

Gabapentin is itself an augmenting agent to numerous other anticonvulsants in treating epilepsy and to lithium, atypical antipsychotics and other anticonvulsants in the treatment of bipolar disorder... 

Sudden unexplained deaths have occurred in epilepsy (unknown if related to gabapentin use)... 

Bromide (1857) was the first drug to be used for the treatment of epilepsy, but it is now obsolete. Phenobarbital, introduced in 1912, controlled patients resistant to bromides. The next success was the discovery in 1938 of phenytoin (a hydantoin) which is structurally related to the barbiturates. Since then many other drugs have been discovered, but phenytoin still remains a drug of choice in the treatment of major epilepsy. Over the past ten years there has been a dramatic increase in the number of new anticonvulsant drugs (vigabatrin, gabapentin, lamotrigine, topiramate, oxcarbazepine, levetiracetam), but none has been shown to be superior to the major standard anticonvulsants (phenytoin, carbamazepine and sodium valproate). 

Gabapentin is effective only for partial seizures and secondary generalised epilepsy (not absence or myoclonic epilepsy), in combination with established agents. It is also used for neuropathic pain. Gabapentin may cause somnolence, imsteadiness, dizziness and fatigue. 

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