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51 terms

THEOPHYLLINE kinetics

STUDY
PLAY
FALSE (poorly soluble)
TRUE/FALSE - theophylline is water soluble
aminophylline
The salt of theophylline is _____
170 (85%)
200mg of IV aminophylline yields ____ theophylline
CHADS G (cardiac dx, hepatic dx, age, drug interactions, smoking, gender)
Theophylline dosing depends on what factors?
4-5mg/kg (over 30mins)
Loading dose of IV theophylline is ______
0.5mg/kg/hr
Maintenance dose of IV theophylline is ____
200-300mg po TID/QID (non-sustained release), 200-400mgpo BID (sustained release)
average Maintenance dose of oral theophylline is ____
5-15mcg/ml
As a bronchodilator, the therapeutic range of theophylline is ______
5-10mcg/ml
As a treatment for neonatal apnea, the therapeutic range is ____
20mcg/ml
What is the toxic serum level of theophylline?
50% increase in FEV1
With a serum level of 5mcg/ml, you would see what effect?
75% increase in FEV1
With a serum level of 10mcg/ml, you would see what effect?
85% increase in FEV1
With a serum level of 15mcg/ml, you would see what effect?
toxic (85% increase in FEV1 can be achieved at 15mcg/ml)
With a serum level of 20mcg/ml, you would see what effect?
12.8mcg/ml
Stable asthmatics see no improvement in theophylline levels over _____
FALSE
TRUE/FALSE - intermittent bolus administration of theophylline is more efficacious than continuous infusion
TRUE (only see a reduction of dyspnea)
TRUE/FALSE - no improvement in COPD pulmonary function tests is seen with theophylline
CNS, CV, kidneys, GI, lungs (caffeine effects to an extreme, tachycardia, diuresis, nervousness, seizures, insomnia)
What systems does theophylline affect?
85
___% of people get theophylline side effects at concentrations of 25mcg/ml
10
___% of people get theophylline side effects at concentrations of 20mcg/ml
16x greater
Elderly have how much more of a chance of having side effects?
parenteral, oral soln, regular and enteric coated oral tablets, IR and SR capsules, granules, rectal solutions and suppositories
How is theophylline available? (dosage forms)
1-2hrs
Liquid or nonsustained release theophylline dosage forms peak in how long?
100%
Sustained release theophylline tablets have how much bioavailability?
TRUE
TRUE/FALSE - the rate of absorption of theophylline is affected by food
TRUE
TRUE/FALSE - bioavailability of theophylline is different between patients
FALSE (night absorption more slow)
TRUE/FALSE - absorption of theophylline is higher at night
14-70mins
What is the time to onset of theophylline?
TRUE
TRUE/FALSE - theophylline crosses placenta and breast milk and CSF
40
Theophylline is ___% protein bound
0.5 (higher in premies and cyctic fibrosis)
What is the Vd of theophylline in adults and peds over 1yr?
20%
What percentage of theophylline is excreted unchanged in the urine?
80%
What percentage of theophylline is metabolized by the liver?
neonates (under 1 year old)
In what population does theophylline change to caffeine during metabolism?
fairly active
Theophylline has _____ metabolites
0.04L/kg/hr (using IBW)
What is the clearance of theophylline?
CHF, influenza, pulmonary disease, hepatic cirrhosis, renal disease (all decrease clearance)
What diseases affect the clearance of theophylline?
phenobarbital, phenytoin, rifampin
What drugs cause an increase in theophylline clearance?
erythromycin, cipro, cimetidine, propranolol, fluvoxamine (and many more)
What drugs cause a decrease in theophylline clearance?
8hrs (shorter/faster in kids and smokers, longer/slower in CHF,elderly and obese, much slower in neonates)
What is the average theophylline halflife in an adult?
smokers, kids
Theophylline has a shorter/faster half-life in what populations?
CHF, elderly, obese, neonates (VERY slow in neonates)
Theophylline has a longer/slower half-life in what populations?
steady state
Trough is most reliable at _____
30mins after LD, then at SS
When should theophylline levels be sampled on IV administration?
2hrs (for IR) 4hrs (for SR) 10hrs (for QD formulations)
When should theophylline levels be sampled on oral administration?
activated charcoal 1g/kg with 75-100ml of sorbitol
Give a treatment for theophylline toxicity
100mcg/ml (patients young, suicide)
Acute ingestion of theophylline that reach levels of ______ can cause seizures and arrhythmias
60mcg/ml (older patients, more serious)
Chronic ingestion of theophylline that reach levels of ______ can cause seizures and arrhythmias
6mg/kg IV amino, 2mg/kg q8-12hrs (no more than 6mg daily - 5mg/kg po theophylline)
LD and MD of theophylline for apnea of prematurity
trough on day 4 (levels more accurate - 1hr after IV or 2hrs after po)
In the treatment of apnea of prematurity, when should levels be drawn?
50%
Increase dose by no more than ____ when treating premature apnea