Table 2.

Main pharmacokinetic characteristics of antiepileptic drugs

	PB†	Oral	T ½ §	M/P¶
			(hours)
		Bioavailability ‡
	(%)	(%)
Carbamazepine	74	100	18 – 54	0.69
Clonazepam	50 – 86	100	18 – 50	0.33
Diazepam	99	100	43	0.2 – 2.7
Ethosuximide	NA	100	30 – 60	0.94
Gabapentin	< 3	50 – 60	5 – 7	0.7 – 1.3
Lamotrigine	55	98	29	0.057 – 1.47 [33]
Levetiracetam	< 10	100	6 – 8	0.76 – 1.55 [37,38]
Oxcarbazepine	40	100	9 (oxcarbazepine metabolyte)	0.5
Phenobarbital	51	80 – 100	20 – 133	0.4 – 0.6
			(45–500 in newborns) [41]
Phenytoin	89	70 – 100	6 – 24	0.18 – 0.45
			(20–160 in preterm infants) [48]
Pregabalin	NA	90	6	NA
Primidone	25	90	5 – 18	0.72
Tiagabine	96	90	7 – 9	NA
Topiramate	15	75	18 – 24	0.86 – 1.1 [55]
Valproate	94	100	14	0.42
Vigabatrin	NA	50	7	< 1
Zonisamide	40	NA	63	0.93

^† PB: maternal plasma protein binding expressed as percentage.

^‡ Oral Bioavailability: intestinal absorption after oral administration expressed as percentage of the administered dose.

^§ T ½: half-life of the drug.

^¶ M/P: milk to plasma ratio of a drug concentration.

Data drawn from references 1–8 except where otherwise specified. NA: indicates that no data are available.