Xanthine Derivatives Flashcards

1
Q

Give 2 examples of xanthine derivatives

A
  • Aminophylline

- Theophylline

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2
Q

On what basis should xanthine derivatives be prescribed?

A

By brand

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3
Q

What are the pharmacological effects of xanthine derivatives comparable to?

A

Caffeine and theobromine

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4
Q

What are the pharmacological effects of xanthine derivatives?

A
  • Allows bronchial smooth muscle relaxation

- Increases heart rate, contractility, and force of contraction

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5
Q

What are the routes of delivery of xanthine derivatives?

A

PO and IV

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6
Q

Why can xanthine derivatives not be given IM?

A

Too irritant

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7
Q

If xanthine derivatives are to be given IV, how should this be done?

A

Very slow IV injection over at least 20 mins

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8
Q

What are the indications for xanthine derivatives?

A
  • Asthma

- COPD

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9
Q

When should xanthine derivatives be used with caution?

A
  • Elderly patients
  • Heart failure
  • Arrhythmias
  • Other cardiovascular disease
  • Liver damage
  • Hyperthyroidism
  • Hypokalaemia
  • Viral infections
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10
Q

Can xanthine derivatives be used when breastfeeding?

A

Should avoid breastfeeding for a couple of hours after taking aminophylline

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11
Q

What monitoring should be done with xanthine derivatives?

A
  • Monitor plasma theophylline concentration 4-6 hours after modified released
  • Monitor plasma potassium in severe asthma
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12
Q

What is the target plasma theophylline?

A

10-20mg/L

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13
Q

Why should plasma theophylline be measured 4-6 hours after modified release administration of xanthine derivatives?

A

To establish if drug is within therapeutic range

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14
Q

Why do you need to ensure xanthine derivatives are within the therapeutic range?

A

As they have a narrow therapeutic index

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15
Q

Why should plasma potassium be monitored in severe asthma being treated with xanthine derivatives?

A

Risk of hypokalaemia with multiple medications (beta-2 agonists, steroids) taken for severe asthma

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16
Q

What might interact with xanthine derivatives?

A
  • Other xanthine derivatives
  • Smoking
  • Beta-2 agonists
  • Diuretics
  • Drugs that lower seizure threshold
17
Q

What can happen if aminophylline and theophylline are given together?

A

Patient can suffer from arrhythmias and convulsions

18
Q

What effect does smoking have on xanthine derivatives?

A

Reduces plasma concentration of drug

19
Q

What might happen if beta-2 agonists and xanthine derivatives are given together?

A

Increased risk of hypokalaemia

20
Q

What might happen if drugs that lower the seizure threshold are given with xanthine derivatives?

A

Increased risk of seizures

21
Q

Give an example of a drug that decreases the seizure threshold?

A

Quinolones

22
Q

Why can toxicity occur with xanthine derivatives?

A

Narrow therapeutic index

23
Q

What are the common side effects of xanthine derivatives?

A
  • Nausea
  • Vomiting
  • Hypokalaemia
  • Gastric irritation
  • Tachycardia
  • Palpitations
  • Headache
24
Q

What are the rare side effects of xanthine derivatives?

A
  • Pulmonary oedema
  • Arrhythmias
  • Myocardial ischaemia
25
Q

What counselling is required with xanthine derivatives?

A
  • Toxicity

- Smoking habits

26
Q

What counselling is required regarding toxicity with xanthine derivatives?

A

Should warn patients about symptoms of toxicity - seizures, hypotension, arrhythmias

27
Q

What counselling is required regarding smoking with xanthine derivatives?

A

Remind patient to inform you if they start or stop smoking during treatment

28
Q

Why do patients need to tell you if they start or stop smoking during treatment with xanthine derivatives?

A

Dose adjustment may be required if a patient changes their smoking habits