theophylline Flashcards
1
Q
What is theophylline used for?
A
Theophylline is used as a bronchodilator in asthma and stable COPD
2
Q
where is theophylline metabolised?
A
liver
3
Q
what are the contraindications of theophylline?
A
the concentration of theophylline is increased in:
- heat failure
- hepatic impairment
- viral infections
- elderly
Theophylline concentrations is decreased by smokers, alcohol.
4
Q
How does theophylline work?
A
Theophylline is a xanthine derivative so works by relaxing the muscle around the airways and improves contraction of the lungs.
5
Q
What drugs decrease theophylline effectiveneess (P450 enzyme inducers)?
A
- carbamezapine
- phenytoin
- rifampicin
6
Q
What drugs increase theophylline effectivness?
A
- allopurinol
- beta blockers
- cimetidine
- macrolides
7
Q
What are the drug
interactions of theophylline?
A
- high doses of -beta2agonists with theophylline can cause hypokalaemia.
- ciprofloxacin inhibits P450 enzymes causing theophylline toxicity
- adenosine (theophylline reduces it’s effect)
- halothane (risk of arrhythmias)
- Ketamine (seizure risk)
8
Q
what are the side effects of theophylline?
A
- irritability
- caffeine life effects - mild (headache, nausea, diarrhoea, trouble sleeping)
- increase in urination
