Aminophylline Intravenous for Adults

Who can administer

May be administered by registered competent doctor or nurse/midwife

Loading dose only given if patient not previously on oral theophylline or aminophylline (but see Further information below)
See monitoring requirements below
To avoid excessive dosage in obese patients, dose should be calculated on the basis of ideal body weight for height (patient is obese if actual body weight is 20% or more above ideal body weight or BMI > 30) ^{(ref 1)}
There are numerous important interactions - check latest BNF
For Y-site compatibility see below

Aminophylline 250mg per 10ml ampoule

Already in solution

Draw up using a 5 micron filter needle

Sodium Chloride 0.9% or Glucose 5%

Intermittent intravenous infusion (loading dose only) ^{(ref 2)}

Continuous intravenous infusion (administer using an electronically controlled infusion device)

Add required dose to a suitable volume of infusion fluid e.g. 500mg to 500ml = 1mg/ml
Administer at a rate as per 'dose' below
Fluid restricted: can be administered undiluted^{(ref 5)}

Usual dose

Loading dose first (if appropriate)

Loading doses must NOT be given to patients already taking oral theophylline or aminophylline (but see Further information below)
Doses should be based on ideal body weight for height - see Important information
Give 6mg per kg (usually 250 to maximum 500mg), followed by maintenance dose.
If patient experiences acute adverse reactions while loading dose is being given, the infusion may be stopped for 5 to 10 minutes, or administered at a slower rate ^{(ref 3)}

Maintenance dose

Patient	Maintenance dose FIRST 12 hours	Maintenance dose BEYOND first 12 hours
Healthy, NON-smokers	0.7mg/kg/hour	0.5mg/kg/hour - adjusted according to plasma theophylline concentrations
ELDERLY patients	0.6mg/kg/hour	0.3mg/kg/hour - adjusted according to plasma theophylline concentrations
Congestive HEART FAILURE/LIVER FAILURE	0.5mg/kg/hour	0.1 to 0.2mg/kg/hour - adjusted according to plasma theophylline concentrations
SMOKERS	Often higher maintenance doses are required ^{(ref 6)}

The half-life is variable (range 7 to 9 hours) (non-smoking, otherwise healthy asthmatic patient)
The half-life may be prolonged or reduced in other disease states - for examples see maintenance dose table above
Monitor potassium - may cause hypokalaemia
Monitor ECG, heart rate and blood pressure ^{(ref 2)}
Desired levels: 10 to 20 microgram/mL^{(ref 3)}
Adverse drug reactions may occur within the range of 10 to 20mg/L. Levels above 20mg/L are more likely to be associated with adverse effects
Take serum level 30 minutes after the loading dose has been given ('post-loading dose level')
Start the continuous infusion once the loading dose is complete, and recheck level after 12 hours- (to determine if levels are increasing or decreasing from post-loading dose level)
Monitor levels regularly and adjust dose according to levels and adverse effects

Loading doses: Ideally the loading dose would be deferred until serum theophylline levels are known. If this is not possible, and if the clinical situation requires that the drug be given, a dose of 3.1mg/kg of aminophylline may be considered, on the basis that it is likely to increase the serum theophylline concentration by about 5 mcg/L when administered as a loading dose
Note: while the loading dose may be administered by slow IV injection- it must be given over 20 minutes- so for practicality, it is best to administer as a short infusion instead
Patients on intravenous aminophylline need careful monitoring and nursing attention
Rapid administration has been associated with acute hypotension, arrhythmias and convulsions
Concurrent use of other xanthine derivatives are contraindicated due to the risk of toxicity
Each 0.5mg/kg aminophylline administered as a loading dose gives rise to a 1mcg/ml increase in serum concentrations of theophylline
Patient is obese if actual body weight is 20% or more above ideal body weight or BMI > 30 ^{(ref 1)}
Ideal body weight (IBW) calculations
- Male 50kg + (2.3 x inches over 5 feet) or 50kg + (0.9 x cm over 152 cm)
- Female 45.5kg + (2.3 x inches over 5 feet) or 45.5kg + (0.9 x cm over 152 cm)

Store below 25⁰C

1: Sanford guide to antimicrobial therapy - online v 7.0.3 ^{(information on obesity extrapolated from data on antimicrobials)}

2: Injectable medicines guide Medusa, accessed online 26/03/2025

3: SPC Mercury pharmaceuticals October 2020

4: Uptodate: accessed 27/03/2025

6. Martindale- accessed online 27/03/2025

Bronchodilator - Theophylline

BNF