Sympathomimetics

Question 1

Name a sympathomimetic.

Answer 1

Theophylline - high risk drugs

Question 2

What formulation dose it most commonly come in? and why?

Answer 2

M/R prep - so delays in toxicity

Why? its prescribed by brand as bioavailability does differ between brands

Question 3

What are toxicity symptoms?

Answer 3

vomiting 
restlessness
convulsions, ventricular arrhythmias - serious 
dilated pupils 
tachycardia
hyperglycaemia

Question 4

What would you give to a patient who has overdosed on theophylline?

Answer 4

convulsions - lorazepam or diazepam

- repeated doses of activated charcoal is given to them - usually if more than an hour has elapsed

Question 5

What causes plasma increase or decrease concentrations for theophylline? what actions must you take?

Answer 5

It DECREASES in:
- Smoking - theophylline conc will start increasing if someone stops smoking therefore overall dose must be reduced.

• alcohol consumption
• medicines that induce metabolism

It INCREASES in:
- HF

• viral infections
• hepatic impairment
• elderly
  medicines that inhibit metabolism

Question 6

What’s the safe range of theophylline?

Answer 6

10-20mg/L - this is whats needed for satisfactory bronchodilation
it has a narrow therapeutic index

Question 7

Name a difference between aminophylline and theophylline.

Answer 7

aminophylline is twice more soluble than theophylline