Few animal studies have proved that gabapentin has a potential to activate a serotonin receptor (5HT3) at the spinal level and also attenuate the function of microglial cells.
In some parts of the brain such as periaqueductal grey (PAG) and anterior cingulated cortex, gabapentin has been shown to elevate the level of GABA, a major inhibitory neurotransmitter, which might serve as an explanation of its’ efficacy in partial management of seizure. Although gabapentin is approved to be used as an add-on treatment of focal epilepsies in 6 years and older patients and as monotherapy in patients older than 12 years of age, it seems to show no efficacy when used in a management of generalized tonic-clonic seizures, generalized absence…show more content… Due to an effect of gabapentin at the level of hypothalamus to regulate the temperature, it can also be used as an effective non-hormonal therapy for hot flashes, a bothersome problem of menopause. It is shown to be more efficacy if used in patients with hot flashes that associated with sleep interference . Study shows that a bioavailability of gabapentin is low and it is dose-dependent. The bioavailability of 300 mg is around 60% and decreasing to less than 30% if the dosage is 1600 mg 3 times a day [4; 11]. It has low protein binding property and it is eliminated unchanged in the urine, which means it will not change into toxic metabolite or intermediate that can be harmful to the body. Gabapentin has a short half life of 5 to 9 hours, but with renal impairment, it will increase. A dose adjustment is required in patient who has creatinine clearance of 60 ml/min and in the elderly because of reduced renal function that has been thought to be decreased around 1% per year after the age of 40[4; 16]. A number needed to treat (NNT) of gabapentin is 6.3 and its number needed to harm (NNH) is 25.6, therefore it is considered a safe drug . The ceiling effect has been reported to be 100 mg/kg in one study and 30-300 mg/kg in another study following oral administration . The pharmacokinetic of absorption of gabapentin is not linear unlike other newer anti-seizure medications. The explanation for this event is because gabapentin absorption depends on