Pharmacology - Xanthines By Jim Clarke

Why Use Xanthines? Used as bronchodilators for asthma and COPD patients Not as widely used in the 90’s as has been the case in the past Now considered to be second or third-line drugs in treatment of asthma & COPD

Types of Xanthines Caffeine - limited bronchodilating effect Theobromine - found in cocoa Theophylline preparations has been widely used as a bronchodilator years ago used as a dieuretic

Physiological Effects of Xanthines Central Nervous System stimulant Stimulates cardiac muscle Increases diuresis Relaxes bronchial, vascular and uterine smooth muslce Peripheral & coronary artery vasodilation Cerebral vasoconstriction

How Theophylline Bronchodilates Currently there are 3 theories; Inhibition of Phosphodiestarase Antagonism of Adenosine Increases production of catecholamines Theophylline preparations also may increase breathing muscle strength

How Theophylline is Given I.V. Preparations - Aminophylline P.O. Preparations Bronkodyl Elixophylline Slo-Phylline Theo-Dur Choledyl

Side Effects Nausea, vomiting, anorexia, diarrhea Cardiac arrhythmias, hypotension Tachypnea Headache, restlessness, insomnia, anxiety Seizures

Monitoring Blood Levels Theophylline levels should be between 5 and 20 mcg/ml Levels > 30 mcg/ml can cause cardiac arrhythmias Levels > 40 mcg/ml can cause seizures

Agents That Effect Theophylline Blood Levels Decrease blood levels Beta agonists Cigarette smoking Increase blood levels Cirrhossis & hepatitis Corticosteroids Beta-blockers

Clinical Uses Not recommended as a first-line drug in asthma treatment Only recommended in asthma when the more typical agents have not worked ATS guidelines DO recommend it’s use in treatment of exacerbations of COPD Can cause severe gastric upset

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