Drug managment Flashcards
Digoxin.. how does it circulate through the body? Metabolism, and half life?
20-30% Dig bound to alb
80% excreted unchanged by kidneys
20% metabolized by liver
serum 1/2 life: 36-38 hr
when does digoxin peak after oral dose and what is the therapeutic range
Oral dose, digoxin peaks in 30-90min, declines till plateau after 6-8 hr
*don’t draw blood till after this 6-8 hr
Range: 0.5-2 ug/100mL
Do you use loading dose with Dig?
Yes, if need earlier effect (unlike warfarin)
start with 0.25-0.5mg STAT then give 0.25mg every 6-8 hr till total of 1-1.5mg given
what is the maintenance dose with dig
0.125-0.25mg/d
IV vs oral for digoxin and onset of action
IV: dig onset in 15-30min
oral: w/in 2 hr
how does reduced renal function affect digoxin levels
ELEVATES (reduces excretion).. may increase 1/2 life from 36 hr to 5 days
*amt of dig depends on pt.. some pt can have adequate dig effect w/ below normal blood level
frequency of Dig toxicity and predisposing factors?
May occur in 5-15% of pt
Risk: electrolyte abn (esp low K), drug interaction, hypoxemia, hypoTH, renal insuff, volume depletion
Cardiac SE of dig are. Other SE??
PVC, AV block ,Vtach, **PAT WITH BLOCK
Other: anorexia, N/V, diarrhea (which can make hypoK worse)
*altered mental status, agitation, vision color changes
tx for dig toxicity
depends on clinical feature and blood level:
- dc drug
- ensure adequate K
- cardiac monitoring
- correct exacerbating factors
- antiarrhythmic meds if needed
- avoid cardioversion except as last resort
DIGIFAB for life threatening when no other available
*40mg vial = 0.6 mg dig
What is Dilantin (phenytoin)
commonly used anticonvulsant (usually 300 mg/d)
*occasionally used as anti-arrhythmic
How safe is Dilantin (phenytoin), what is the therapeutic range and how do you determine adequacy of next dose
Narrow therapeutic window
excess is toxic
THERAPEUTIC range: 10-20ug/mL
*draw blood before next dose to get levels
*also, if toxic sx present, get drug levels during sx or peak levels
How does Dilantin/phenytoin circulate throughout the body. How is it metabolized?
90% bound to serum pro
70%** METABOLIZED IN LIVER
5% excreted unchanged in kidney
when do you get peak levels of Dilantin
4-8 hr after oral dose or 15 min after IV
Serum half life 24 hr, steady state achieved 4-6 days after starting
what is the key to phenytoin pharmacology
dose response curve is not linear, small increases may result in very large increase in serum level
what are common SE of phenytoin/Dilantin
RASH (morbilliform or sever exfoliative)
LETHARGY
MEGALOblastic anemia (responds to folic acid)
Benign Lymphoid hyperplasia
GINGIVAL HYPERTROPHY (also in “dipine” CCB)
HIRSUTISM
rash, tired, big anemia, gingiva, LAD, Hairy
what would be an excessive phenytoin blood level and what clinical findings might indicate this
> 20 ug/mL = pheny toxic
findings:
lethargy, nystagmus/tremor, ataxia, reduced coordination, dizzy, slurred speech
*LOTS OF NEURO SX with pheny toxic
A pt comes in lethargic, ataxic, slurring speech and losing balance. You find out they have blood level of 21 ug/mL of phenytoin. How do you treat their phenytoin toxicity
NO ANTIDOTE :( poor pheny
supportive care, follow blood levels, hemodialysis possibly
what percent of pt with AMI don’t even have classic chest pain? what about nondx ECG of pt who actually end up having an AMI
1/4 pt don’t have chest pain
1/2 have nondx ECG
Acute Coronary syndrome consists of
- unstable Angina
- STEMI (AMI)
- NSTEMI (AMI)
what are classifcations for unstable angina
- min exertion or at rest >10min or 20min
- New onset (past 4-6 wk) and severe (limits PA)
- Worse than previously (crescendo pattern)
- more sever, more prolonged, more frequent
what are descriptions for noncardiac chest pain
Pleuritic - sharp, knife like, hurt when cough or breath
Mid to lower abdomen
discomfort localized with one finger
discomfort reproduced by mvmt of palpation
constant pain lasting for days
Fleeting pain lasting sec
pain radiating to legs or above mandible
what are the cardiac enzymes
CK-MB
Troponin more sensitive and specific
*if normal ecg and CK-MB but elevated troponin, may still indicate MI
Criteria for MI
rise and fall of cardiac enzyme PLUS
a) ischemic sx
b) new Q wave
c) ECG changes: ST elevation or depression
d) imaging evidence of new loss of viable myocardium or new regional wall motion abn
the line bw UA and MI…
UA: sx but no enzyme or EKG indications
MI: assumed if troponin and/or CK-MB are elevated
