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exam 3 pharm
ch 22
| Question | Answer |
|---|---|
| anticonvulsants | stabilize nerve cell membranes and suppress abnormal electrical activity in cerebral cortex |
| action of anticonvulsants | 1. suppress sodium influx, prolonging channel inactivation, prevents neuron firing 2. prevents electrical current generated by Ca ions to the t-type calcium channel 3. increases the action of GABA, which inhibits neurotransmitter throughout the brain |
| drugs that suppress sodium influx | phenytoin, fosphenytoin, carbamazepine, valproic acid, toprimate, zonisamide, lamotrigine |
| drugs that suppress calcium influx | valproic acid and ethosuximide |
| drugs that enhance the action of GABA | barbits, benzos, tiagabine |
| drug that promotes GABA release | gabapentin |
| hydantoins | ☺act by inhibiting sodium influx, stabilize cell membraines, reduce repetitive neuronal firing ☻also used for dysrhythmias by increasing the electrical stimulation threshold in cardiac tissue ♥do not use in pregnancy due to teratogenic effect on fetus ♦drug dose is age related - slower metabolism in older adult means lower dose, high metabolism in children means higher dose ♣dosage is adjusted according to therapeutic plasma or serum levels |
| phenytoin therapeutic level and stuff (I am tired of this stuff) | ☺10-12 mcg/mL ☻highly PB ♥IV admin by direct injection into a large vein ♣may be diluted in saline, do NOT use dextrose cause it will precipitate ♠IV infusion rate greater than 50 mg/min may cause HoTN or dysrhythmia, local irritation and sloughing ♦do not give IM |
| s/e and a/e of hydantoins | slurred speech, confusion, depression, thrombocytopenia, leukopenia, gingival hyperplasia, hyperglycemia (drug inhibits insulin), n/v, constipation, drowsiness, HA, alopecia, hirsutism, nystagmus |
| drug-drug interactions hydantoins | ☺compete with highly protein bound drugs, anticoags, asa ☻barbits, rifampin, ethanol increase hydantoin metabolism ♥sulfonamides and cimetidine increase action by inhibiting liver metabolism ♦antacids, antineoplastic drugs decrease absorption ♣antipsychotics and herbs lower seizure threshold and increase seizure activity |
| barbits | phenobarbital - long acting ☺used for: status epilepticus seizures, meningitis, toxic reactions, eclampsia ☻therapeutic level: 20-40 mcg/mL ♥taper to d/c ♦s/e: resp depression, confusion, depression, irritability a/e: SI, physical dependence |
| succinimides | ethosuximide ☺treats absence or petit mal seizures ☻therapeutic range - 40-100 mcg/mL ♥a/e: blood dyscrasias, renal/liver impairment, SLE |
| benzos | clonazepam, clorazepate dipotassium, and diazepam ☺clonazepam - petit mal but tolerance may occur w/i 6 months ☻diazepam - acute status epilepticus, must be admin IV, short-term effect, must give phenytoin or phenobarbital during or immediately after |
| iminostilbenes | carbamazepine ☺treats refractory seizure disorders that have not responded to other drugs ☻also used for psychiatric disorders, bipolar disorder, trigeminal neuralgia, and etoh w/d ♥therapeutic level: 5-12 mcg/mL ♦no grapefruit juice |
| valproate | valproic acid, divalproex sodium (Depakote) ☺not established as safe for small children ☻hepatoxicity therapeutic level: 50-100 mcg/mL ♥also used for bipolar and migraine ♦avoid during pregnancy |
| anticonvulsants and pregnancy | ☺pregnancy causes seizures to ↑ by 25% ☻hypoxia can harm the fetus ♥phenytoin and carbamazepine are linked to fetal abnormalities of the heart and cleft palate, valproic acid is known to cause major congenital malformation ☺anticonvulsants act as inhibitors for vit K contributing to hemorrhage in infants - give oral vit K supp for the last 10 days of pregnancy ☻anticonvulsants increase the loss of folate - take daily folate supp |
| anticonvulsants and febrile seizures | ☺usually occur in children 3 mo - 5 yrs old ☻do not use valproic acid in children <2 yo ♥epilepsy develops in 2.5% of children that have febrile seizures ♦phenobarbital or diazepam are used prophylactically |
| NC phenytoin | ☺assess pts knowledge regarding medications ☻urinary output must be >1500 mL/day ♥lab values for renal and liver, if both BUN and creatinine are elevated then renal disease is suspected ♦therapeutic range: 10-20 mcg/mL; toxic level 30-50 ♣seizure precautions ♠may cause anorexia, make sure pt is receiving adequate nutrition |
| teach phenytoin | ☺shake suspension ☻don't get pregnant on phenytoin or valproic acid ♥monitor phenytoin levels closely while pregnant (did you not just hear me tell you not to get pregnant?) ♦no etoh or CNS depressants ♣taper off medication ♠regular dental appts •get regular lab tests ◘monitor glucose levels closely - hyperglycemia |
| s/e of phenytoin | ☺urine will be a harmless pinkish or redish color ☻use a soft toothbrush ♥report sore throat, nosebleeds, bruising - may indicate a blood dyscrasia ♦report gingivitis, nystagmus, slurred speech, s-j syndrome starts with a rash |
| status epilepticus tx | ☺diazepam (valium) IV or lorazepam (Ativan)followed by phenytoin IV ☻if seizure continues midazolam (versed) or propofol (diprivan) and then high dose barbiturates ♥admin slowly to avoid resp depression |
| clonazepam | ☺used for petit mal, myclonus and status epilepticus |
| diazepam (valium) | ☺status epilepticus - drug of choice ☻admin slowly to prevent resp depression ♥repeat q10-15 min up to 30 mg PRN then q2-4 hr PRN ♦also used to treat anxiety and substance abuse w/d |
| lorazepam (ativan) | ☺use to treat status epilepticus ☻infusion rate should not exceed 2 mg/min♥ ♥also used to treat anxiety and substance abuse w/d |
| carbamazepine (tegretol) | ☺for tonic clonic, partial, simple, complex seizures ☻also used to treat bipolar disorder ♥t/r: 5-12 |
| gabapentin (neurontin) | ☺used as an adjuctive therapy for partial seizures ☻give with food to prevent GI upset ♥taper to d/c ♦max dose 3600 mg/d - high doses are used short term |
| lamotrigine (lamictal) | ☺maintenance dose: 250 mg BID ☻used for partial and tonic clonic, tx of Lennox-Gastaut syndrome ♥blocks sodium influx ♣d/c if rash appears as it may be the start of s-j syndrome |
| pregabalin (lyrica) | ☺used for partial seizures and fibromyalgia ☻affects calcium channels in CNS ♥0% PB |
| PB for anticonvulsants | all are highly PB except for phenobarbital |
| herbal alert | ☺evening primrose and borage may lower seizure threshold ☻gingko may decrease phenytoin effectiveness |
Created by:
nursingTSJC2013
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