1. Methylxanthines
RC 195

2. Types of Methylxanthines
Caffeine
Theobromine
Theophylline
Most common methylxanthine used in respiratory care

3. Methylxanthine Effects
Bronchodilation
Cerebral stimulation
Skeletal muscle stimulation
Vasodilator
Cardiac stimulation
Smooth muscle relaxation
Diuresis

4. Theophylline Common Brands
Aminophylline
IV administration while hospitalized
Oxtriphylline
Oral form
Choledyl, TheoBid, TheoDur
Combinations (Theophylline and sympathomimetc)
Oral preparations: Marax, Tedral, Quibron, Slo-Phylline

6. Theophylline Duration
3-9 ½ hours
Is deactivated in liver
Desired effects and side effects are determined by serum, ie plasma, levels

8. Signs that indicate need to check serum Theophylline levels
N &V
Thirst
Agitation
Arrhythmias

9. Factors that decrease Theophylline clearance
CHF
Pneumonia
Pulmonary Edema
Hepatic problems
Drugs- eg, Cimetidine, Erythromycin, Propranolol
These patients are prone to high serum levels and toxicity

10. Factors that increase Theophylline clearance
Cigarette smoking
Being a pediatric patient
Acidosis
These patients may need higher doses to achieve therapeutic levels

11. Routes and Dosages IV
Loading dose is 6 mg/kg over thirty minutes (why?) or 3 mg/kg in a patient who has received Theophylline within last 24 hours
Maintenance dose:
.9 mg/kg/hour for person who smokes
.5 mg/kg/hour for non-smoker
.25 mg/kg/hour in a patient with decreased clearance

12. Routes and Dosages (cont.)
Oral – mg TID or QID
TheoBid and Theodur are BID
Rectal – 500 mg
IM – mg
Very painful so not a commonly used route
Theophylline is rarely aerosolized!
Variable serum levels and intense coughing

13. Drug Interactions Antagonizes Propranolol Potentiates sympathomimetics
Additive with diuretics
Antibiotics – variable. May also cause precipitation if mixed in same IV line
It is best to administer IV Theophylline in its own IV line

14. Time for a case study!