Flashcards in Phenobarbital Deck (14)
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1
What is the class of Phenobarbital?
Barbiturate
2
What is Phenobarb used for?
to treat insomnia and preop for sedative effects;
anticonvulsant for acute trtment of partial seizures and tonic-clonic seizures
3
What is the MOA of Phenobarb?
-potentiates GABA
-mimics GABA
-increases influx of Cl- hyperpolarizing the membrane
-depresses the sensory cortex, causes drowsiness/sedation, decreases motor activity
4
How is phenobarb metabolized?
CYP450 inducer and metabolized in liver by hydroxylation and glucuronide conjugation. also excreted unchanged in the urine as high as 60%-90%!!
5
What is the e 1/2 l for phenobarb?
53-140 hours
6
What is the onset for PO? IV? for phenobarb
20-60 min onset PO
5 min IV
7
What is the DOA of phenobarb? PO? IV?
po 6-10 hours
IV 4-10hours
8
IS phenobarb protein bound?
weakly to moderately PB 20-40%
9
What are side effects of Phenobarb?
-BM suppression
-Agranulocytosis
-Thrombocytopenia
-Liver toxicity
-Osteopenia
-Rash
-Stevens-johnson
-apnea
-respiratory depression
- sedation
-insomnia
-hallucinations
-confusion
-dizziness
-n/v
10
What are the contraindications to phenobarb?
-Hypersensitivity to barbs
-resp disease
-dyspnea
-a/w obstruction
-severe liver disease
-porphyria
-pregnancy
11
What are drug interactions with Phenobarb?
they are enzyme inducers! increased metabolism of:
-Phenytoin
-Antiarrhythmics
-anticonvulsants
-antipsychotics
-beta blockers
-CCBs
- Cimetidine
-loop diuretics
12
What are CYP2C19 inducers that would decrease the levels of effectiveness of Phenobarb?
-aminoglutethimide
-Carbamazepine
-phenytoin
-rifampin
13
What is the pre-op sedation dose of phenobarb?
IM 100-200mg 1-1.5hrs before the procedure
14
