'"`UNIQ--vote-00000013-QINU`"' Strong CYP3A4 induction via the phenobarbital metabolite produces many interactions (reduces oral contraceptives, warfarin, many psychotropics). Essential-tremor efficacy is the unique pharmacological selling point'"`UNIQ--ref-00000014-QINU`"'.
Seizures: 100-125 mg PO at bedtime x 3 days, then BID, then TID, escalating to 750-1500 mg/day. Essential tremor: 25-50 mg PO at bedtime, titrate slowly to 250-750 mg/day
preparations
String
Tablets 50, 250 mg
fda_max
String
2 g/day (seizures); typically much lower for essential tremor
pill_id
Text
routes
List of String, delimiter: ,
Oral
onset
String
Anticonvulsant effect emerges with slow titration over weeks; tremor effect over weeks
duration
String
BID-TID dosing
halflife
String
Primidone 5-15 hours; '''phenobarbital active metabolite 50-150 hours'''; PEMA (phenylethylmalonamide) active metabolite 16 hours'"`UNIQ--ref-00000017-QINU`"'
bioavailability
String
~90% (oral)'"`UNIQ--ref-00000018-QINU`"'
pregnancy
String
Substantial teratogenic signal (barbiturate class effects including neonatal withdrawal and hemorrhagic disease of newborn).<sup class="pcp-cn" title="This claim needs a citation.">[[[Pharmacopedia:Citation needed|citation needed]]]</sup>
legal
String
[[USLegal:Prescription only|Rx-only]] in US. '''Federally non-controlled despite being a barbiturate''', a paradoxical situation given that its primary active metabolite phenobarbital is Schedule IV'"`UNIQ--ref-00000019-QINU`"'
