Xanthine Derivatives Flashcards
Give 2 examples of xanthine derivatives
- Aminophylline
- Theophylline
On what basis should xanthine derivatives be prescribed?
By brand
What are the pharmacological effects of xanthine derivatives comparable to?
Caffeine and theobromine
What are the pharmacological effects of xanthine derivatives?
- Allows bronchial smooth muscle relaxation
- Increases heart rate, contractility, and force of contraction
What are the routes of delivery of xanthine derivatives?
PO and IV
Why can xanthine derivatives not be given IM?
Too irritant
If xanthine derivatives are to be given IV, how should this be done?
Very slow IV injection over at least 20 mins
What are the indications for xanthine derivatives?
- Asthma
- COPD
When should xanthine derivatives be used with caution?
- Elderly patients
- Heart failure
- Arrhythmias
- Other cardiovascular disease
- Liver damage
- Hyperthyroidism
- Hypokalaemia
- Viral infections
Can xanthine derivatives be used when breastfeeding?
Should avoid breastfeeding for a couple of hours after taking aminophylline
What monitoring should be done with xanthine derivatives?
- Monitor plasma theophylline concentration 4-6 hours after modified released
- Monitor plasma potassium in severe asthma
What is the target plasma theophylline?
10-20mg/L
Why should plasma theophylline be measured 4-6 hours after modified release administration of xanthine derivatives?
To establish if drug is within therapeutic range
Why do you need to ensure xanthine derivatives are within the therapeutic range?
As they have a narrow therapeutic index
Why should plasma potassium be monitored in severe asthma being treated with xanthine derivatives?
Risk of hypokalaemia with multiple medications (beta-2 agonists, steroids) taken for severe asthma
What might interact with xanthine derivatives?
- Other xanthine derivatives
- Smoking
- Beta-2 agonists
- Diuretics
- Drugs that lower seizure threshold
What can happen if aminophylline and theophylline are given together?
Patient can suffer from arrhythmias and convulsions
What effect does smoking have on xanthine derivatives?
Reduces plasma concentration of drug
What might happen if beta-2 agonists and xanthine derivatives are given together?
Increased risk of hypokalaemia
What might happen if drugs that lower the seizure threshold are given with xanthine derivatives?
Increased risk of seizures
Give an example of a drug that decreases the seizure threshold?
Quinolones
Why can toxicity occur with xanthine derivatives?
Narrow therapeutic index
What are the common side effects of xanthine derivatives?
- Nausea
- Vomiting
- Hypokalaemia
- Gastric irritation
- Tachycardia
- Palpitations
- Headache
What are the rare side effects of xanthine derivatives?
- Pulmonary oedema
- Arrhythmias
- Myocardial ischaemia
What counselling is required with xanthine derivatives?
- Toxicity
- Smoking habits
What counselling is required regarding toxicity with xanthine derivatives?
Should warn patients about symptoms of toxicity - seizures, hypotension, arrhythmias
What counselling is required regarding smoking with xanthine derivatives?
Remind patient to inform you if they start or stop smoking during treatment
Why do patients need to tell you if they start or stop smoking during treatment with xanthine derivatives?
Dose adjustment may be required if a patient changes their smoking habits
